JP2003222201A - Planetary gear reduction gear and drive unit using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure higher quietness while avoiding increase of size of a compact reduction gear in a drive unit having the reduction gear used in an actuator of an industrial robot. <P>SOLUTION: This planetary gear reduction gear is provided with a sun gear 14 connected with an input shaft 3 integrally, a plurality of planetary gears 15 revolving while rotating around the sun gear 14, a ring gear 16 meshing with the planetary gears 15 and fixed to a housing 2, and an output shaft 5 rotating centered on a rotary shaft of the sun gear 14 by the revolution of the planetary gears 15. Each gear 14 to 16 is formed into helical gear. The total meshing rate in meshing of the sun gear 14 and the planetary gears 15 is set in a range of 2.0 to 3.5, and crowning is applied to at least the planetary gears 15. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device with a small planetary gear reducer used for various purposes such as an actuator of an industrial robot, a cleaning device for a rotary press for printing, an automatic wrapping machine, a machine tool, etc. Regarding

[0002]

2. Description of the Related Art An industrial robot having a plurality of arms connected to each other through a plurality of joints may be operated even in the middle of the night, so that high quietness is required. As one of means for improving the quietness of such an industrial robot, it is considered to reduce the operating noise itself generated from the actuator that rotationally drives the joints to drive the arms in a predetermined direction. To be

Generally, the actuator is composed of, for example, a small servo motor and a speed reducer, and the output of the drive shaft of the motor is decelerated at a predetermined reduction ratio and the output is transmitted to the joint. . In actuators used for industrial robots and the like, a speed reducer using a planetary gear is used because it is necessary to have a small size and a large reduction ratio. In particular, a small reducer having a module (a unit representing the size of a tooth profile of a gear) of about 0.3 to 1 and a ring gear having 72 or less teeth is widely used.

In this type of speed reducer, when the meshing ratio between the gears is increased, the number of teeth that share the power to be transmitted increases, and the force that a pair of teeth meshing with each other bears becomes smaller. Therefore, it is known that the quietness of the speed reducer improves as the meshing ratio increases. Therefore, when compared with the same number of teeth, the gear ratio of each gear having helical teeth is larger than that of gears having straight teeth (straight teeth), so that the operating noise is reduced.

[0005]

In a helical gear, the meshing ratio increases with an increase in the twist angle of each gear (the angle formed between the tooth trace and the shaft center of the gear). However, since the axial force (force acting in the axial direction) generated when the gear transmits power increases with the increase of the twist angle, the bearing must be large in order to cope with it. Need to be converted.

That is, as shown in FIG. 7, when the helical angle of each tooth of the helical gear is β, each tooth has an axial axial force due to the rotational force F from the tooth of the mating gear. Since Ftan β is generated, this axial force Ftan
A bearing that can withstand β must be used. When the twist angle β increases, the axial force Ftan β increases, and this increase causes a problem that the entire reduction gear increases in size.

The present invention has been made in view of the above,
An object of the present invention is to provide a small planetary gear reducer that secures higher quietness while avoiding an increase in size of the reducer, and a drive device using this reducer.

[0008]

According to a first aspect of the present invention, there is provided a sun gear integrally connected to an input shaft, a plurality of planet gears that revolve around the sun gear while revolving around the sun gear, and a planet gear. A ring gear fixed to the housing that meshes with the
An output shaft that supports the rotation shaft of each planet gear and that rotates about the rotation shaft of the sun gear by the revolution of the planet gear, and the module of each gear is set in the range of 0.3 to 1. In addition, in a planetary gear reducer including a planetary gear mechanism in which the ring gear is formed with 72 or less teeth, each of the gears is formed as a helical tooth, and the sun gear and the planetary gear are meshed with each other. The sum of the front meshing ratio and the overlapping meshing ratio is set in the range of 2.0 to 3.5.

According to a second aspect of the present invention, in the planetary gear reducer according to the first aspect, the twist angles of the teeth of the sun gear and the planet gears are set in the range of 10 ° to 20 °. It is characterized by that.

According to a third aspect of the present invention, in the planetary gear speed reducer according to the first or second aspect, at least the planetary gear is crowned.

According to a fourth aspect of the present invention, in the planetary gear reducer according to any of the first to third aspects, at least the tooth thickness of the cutting edge portion of the planetary gear is substantially an involute curve when a load is applied. The tooth thickness is specified to be smaller than the tooth thickness specified by the involute curve when no load is applied.

According to a fifth aspect of the present invention, in the planetary gear reducer according to any one of the first to fourth aspects, the ring gear is a positive shift gear.

According to a sixth aspect of the present invention, the planetary gear reducer according to any one of the first to fifth aspects is combined with a motor, and the rotation of the output shaft of the motor is transmitted through the planetary gear reducer. It is a drive device that decelerates at a predetermined reduction ratio and outputs.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a planetary gear speed reducer and a drive system using this speed reducer according to the present invention will be described below. First, the basic configuration of the planetary gear reducer will be described, and then the configuration of the characteristic portion of the present invention will be described.

FIG. 1 is a sectional view of a drive unit with a planetary gear reducer according to a first embodiment.

As shown in FIG. 1, the planetary gear reducer 1 includes
Housing 2, input shaft 3, planetary gear mechanism 4 and output shaft 5
Is disposed on the rotary shaft O, and is configured to reduce the output of the motor M at a predetermined reduction ratio and transmit it to a driven member (not shown) via these members 2 to 5. .

The housing 2 has a stepped cylindrical shape,
The first housing 6 on the input shaft side and the second housing 7 on the output shaft side are integrated by a bolt 8. The motor M is attached with a bolt 9 to a first flange 61 formed at the end of the first housing 6 on the input shaft 3 side.

The input shaft 3 is a member having a plurality of cylindrical peripheral surfaces having different diameters, and is rotatably supported by the ball bearing 10 at the central portion 31 in the axial direction with respect to the first housing 6. The ball bearing 10
The restriction member 11 fitted in the concave groove 62 of the axially central portion 31 of the first housing 6 and the inwardly bulging second flange 63 formed on the left end side of the first housing 6 axially It is fixed to.

The connecting portion 32 located on the motor shaft Mb side of the input shaft 3 has a substantially C-shaped cross section in the direction orthogonal to the rotation axis O, and connects the input shaft 3 and the drive shaft Mb of the motor M. It is a part to do. Female threads 322 are formed at both ends of the connecting portion 32 in the substantially C-shape in the circumferential direction and extend in one direction via a gap 321 between the ends. The motor shaft Mb is clamped to the connecting portion 32 by screwing the bolt 12 into the female screw portion 322 with the motor shaft Mb of the motor M fitted in the substantially C-shaped central hole 323 of the connecting portion 32. The input shaft 3 and the motor shaft Mb are connected.

The fitting portion 3 located on the output shaft 5 side of the input shaft 3
Reference numeral 3 denotes a tubular portion into which the fitting portion 142 of the sun gear 14 is press fitted. The oil seal portion 13 is interposed between the fitting portion 33 and the second flange 63. The oil seal portion 13 is provided to prevent the lubricating oil filled in the second housing 7 from leaking into the first housing 6, and, for example, as is well known, a rubber thin film. The body 13a is surrounded by a biasing spring 13b which is a coil spring and is pressed against the surface of the fitting portion 33. As the lubricating oil, for example, grease in which soaps are mixed with mineral oil or mixed oil is used.

The planetary gear mechanism 4 is provided with a sun gear 14 disposed on the rotary shaft O and a plurality of sun gears 14 arranged at equal intervals around the sun gear 14 and meshing with the sun gear 14 (for example, 3
Two planetary gears 15 (only one planetary gear is shown in the drawing), and a ring gear 1 that meshes with the planetary gears 15.
It is composed of 6 etc. The teeth of each of the gears 14 to 16 are formed as helical teeth, and the part related to the teeth will be described later.

The sun gear 14 has a substantially cylindrical gear portion 141 having helical teeth formed on the outer peripheral surface, and a cylindrical fitting portion having a smaller diameter than the gear portion 141 and extending from the gear portion 141 toward the axial motor M side. And a joint 142. The gear portion 141 meshes with the planetary gear 15, while the fitting portion 142 is press-fitted into the coupling portion 33 of the input shaft 3 so that the gear portion 141 rotates integrally with the input shaft 3. Has become.

Each planetary gear 15 is formed with a through hole 151 penetrating in the axial direction in the central portion thereof, and a pin member 17 planted on the output shaft 5 has a through hole 15 through a bearing 18.
1 is fitted.

The ring gear 16 is circumferentially fixed to the second housing 7 by a connecting pin 19, and
In the recess 21 formed in the housing 2, the ball bearing 20 and the ball bearing 20 are arranged side by side in the axial direction and fixed in the axial direction.

As a result, the planetary gears 15 rotate about the position of the pin member 17 as the sun gear 14 rotates (hereinafter, this rotation is referred to as rotation), while the sun gears 1 rotate.
It rotates about the position of 4 (hereinafter, this rotation is called the revolution).

The output shaft 5 is provided with a columnar portion 51 having a plurality of different outer diameters, and a gap between the columnar portion 51 and the planetary gears 15 and the planetary gears 15 so as to surround the planetary gears 15 behind them. And a planetary gear 1
5 revolves around the rotation axis O. The pin member 17 that connects the output shaft 5 and the planetary gear 15 is embedded in the extending portion 52 of the output shaft 5.

The output shaft 5 is rotatably supported on the second housing 7 by a ball bearing 20 at an end portion on the axial input shaft side and by a ball bearing 21 at a central portion in the axial direction.

Between the proper position of the output shaft 5 and the end of the second housing 7 on the output shaft side, an oil seal portion 22 (rubber thin film body 22) having substantially the same structure as the oil seal portion 13 is provided.
a, an urging spring 22b) are interposed, and the oil seal portion 22 is configured to prevent the lubricating oil filled in the second housing 7 from leaking to the outside.

With the above configuration, the motor M to the input shaft 3
The power transmitted to the sun gear 14 of the planetary gear mechanism 4 is transmitted to the sun gear 14 and the rotation of the sun gear 14 causes
The planet gear 15 revolves around the sun gear 14 while rotating, and the output shaft 5 rotates due to this revolution. As a result, the output of the motor M is decelerated at a predetermined reduction ratio and then output.
The reduction ratio is Z1 / (Z1 + Z), where Z1 and Z2 are the numbers of teeth of the sun gear 14 and the ring gear 16, respectively.
2).

Next, the planetary gear reducer 1 according to this embodiment.
And the characteristic part of the drive device using the same will be specifically described.

The drive device using the planetary gear reducer 1 according to the present embodiment is used for an actuator of an industrial robot as described above. For example, the axial dimension L = 110 mm, the radial dimension. It is as small as D = 50 mm. The module of each gear 14-16 is 0.3-
It is about 1.0, and the number of teeth of the ring gear is 72 or less.

In the planetary gear reducer 1 of this embodiment, the twist angles of the teeth of the sun gear 14 and the planetary gear 15 are, for example, 15
Formed in °. Table 1 shows the total meshing ratios of the sun gear 14 and the planetary gears 15. Table 1 compares the meshing ratio of the planetary gear reducer 1 according to the present embodiment with the meshing ratio of the conventional planetary gear reducer in which the teeth of each gear are formed as straight teeth. In Table 1, the reduction ratios are set to 1/3, 1/5, and 1/9, and the engagement ratios are shown separately for each reduction ratio. The method for calculating the front meshing ratio ε1 and the overlapping meshing ratio ε2 is well known, and the front meshing ratio ε1 is calculated by dividing the length of all contact arcs by the pitch circle, and the overlap meshing ratio ε2.
Is calculated from the arithmetic expression ε2 = bsinβ / πm (twist angle β, tooth width b, right angle module m).

[0033]

[Table 1]

As shown in Table 1, in the present embodiment, in the case of the speed reducer in which the reduction ratio is set to 1/3, when the twist angle is 15 °, the front meshing ratio is 1.5 and the overlapping meshing ratio is 1.5. Is 1.2 (total meshing ratio is 2.7).
Further, in the case of a speed reducer in which the reduction ratio is set to 1/5, the front meshing ratio is 1.5, the overlapping meshing ratio is 1.3 (total meshing ratio is 2.8), and the reduction ratio is 1/9. In the case of the set reduction gear, the front meshing ratio is 1.1 and the overlapping meshing ratio is 1.2 (total meshing ratio is 2.3).

On the other hand, in the conventional one, in the case of the speed reducer having the reduction ratio set to 1/3, the meshing ratio is 1.6, and in the case of the speed reducer having the reduction ratio set to 1/5, The meshing ratio is 1.5, and the meshing ratio is 1.2 in the case of the speed reducer in which the reduction ratio is set to 1/9.

In the planetary gear reducer 1 of the present embodiment, as described above, the total meshing ratio of the sun gear 14 and the planetary gear 15 is set in the range of 2.0 to 3.5, so that the conventional planetary gear reducer can be used. Higher quietness is obtained compared to the speed reducer.

Table 2 shows the measurement results of the volume of the operating noise of the planetary gear reducer of this embodiment and the conventional one.

[0038]

[Table 2]

As shown in Table 2, a planetary gear reducer with a reduction ratio of 1/3 has a volume of 8 dB, and a planetary gear reducer with a reduction ratio of 1/5 has a volume of 13 dB and a planetary gear with a reduction ratio of 1/9. The volume of the speed reducer was reduced by 16 dB.

As described above, the teeth of each gear are formed in the shape of a tooth and the total meshing ratio thereof is set in the range of 2.0 to 3.5, whereby the quietness of the planetary gear reducer 1 is reduced. Can be improved. Further, when the helical gear has a twist angle of 15 °, and the rotational force received by the planetary gear 15 from the sun gear 14 is F, the axial force is Ftan 15 °, which is about 27% of the rotational force F. It is a relatively small value. Therefore, in improving the quietness of the planetary gear reducer 1, it is possible to avoid an increase in the size of the planetary gear reducer 1 due to an increase in the axial force.

The torsion angles of the teeth of the sun gear 14 and the planetary gear 15 are not limited to the above values, but can be set in the range of 10 ° to 20 ° so that the total meshing ratio is within a range where the axial force is relatively small. Since it is set in the range of 2.0 to 3.5, the quietness of the planetary gear reducer 1 can be improved.

In the present embodiment, in addition to the above setting of the meshing ratio, as shown by an arrow A in FIG.
4 and the teeth of the planetary gear 15 are crowned so as to bulge along the tooth traces of the gears in order to improve the meshing contact when a load is applied to each tooth. Further, as shown in FIG. 3, the crowning amount a is 0.016 to 0.03 per tooth width (W) 25 mm in the present embodiment.
It may be set to 4 mm. As a result, it is possible to prevent the teeth of both gears from contacting each other at an end portion of the tooth width with excessive contact pressure due to the fact that the axes of the gears that mesh with each other are not parallel. Therefore, the noise due to this contact can be reduced, and the quietness of the planetary gear reducer can be improved.

Although the sun gear 14 and the planetary gear 15 are both crowned in the above embodiment,
At least the planetary gear 14 may be used.

When a load is applied to the teeth of each gear, the teeth are deformed and the tooth contact changes from the ideal state. Since noise is generated due to this, in order to reduce this noise, in the present embodiment, tooth tips are corrected at positions near the fillet portions of the tooth tips of the gears 14 to 16.

That is, when the driving gear rotates the driven gear, first, the tooth root of the driving gear and the tooth tip of the driven gear come into contact with each other. At this time, if the gear has a pitch error or if the gear is elastically deformed by transmitting torque, the driving gear and the driven gear are strongly contacted with each other to generate noise. In order to reduce this noise, when the load is applied, the tooth thickness is almost specified by the involute curve.
Make it thinner than the tooth thickness specified by the involute curve,
It reduces noise.

In this embodiment, as shown by the solid line in FIG. 4, the tip of the tooth is b = 0.006 in the thickness direction of the tooth.
〜0.012mm, and in the height direction of the tooth, distance c = 0.25-0.48mm from the tip of the tooth.
The cutting amount is gradually reduced toward the position of. As described above, by correcting the tooth contact, it is possible to reduce the noise generated due to the change in the tooth contact, and it is possible to improve the quietness of the planetary gear reducer.

Further, in the present embodiment, as shown in FIG. 5, when the ring gear 16 is gear-cut by a predetermined gear cutting tool 24, the reference pitch line L2 of the tool 24 is changed to the reference pitch line L2 of the ring gear 16. It is toothed with a positive dislocation γ (dislocation coefficient +0.5) with respect to L1. In addition, L3 is
The reference pitch circle of the ring gear 16 is shown.

As a result, the ring gear 16 and the planetary gear 1
Since interference with the gear 5 can be prevented, noise generated due to the interference can be reduced, and the quietness of the planetary gear reducer 1 can be improved. The dislocation coefficient is not limited to the above value, but may be set in the range of +0.3 to +1.5.

The present invention can also be applied to a planetary gear reducer having a plurality of stages of planetary gear mechanisms.

FIG. 6 is a sectional view of a planetary gear reducer in which two planetary gear mechanisms are arranged side by side in the axial direction. The planetary gear speed reducer according to the present embodiment is different from the planetary gear speed reducer 1 according to the first embodiment mainly in the portion of the planetary gear speed reduction mechanism. Therefore, this difference will be described. The description of the part is omitted. In addition, about the member which has the same function as the member in the planetary gear reducer 1 of 1st Embodiment, "" is attached | subjected and shown to the number of the member of 1st Embodiment.

In the planetary gear reducer 1'according to the present embodiment, the input shaft 3'connected to the motor shaft Mb is the first
Is connected to the sun gear 411 of the planetary gear speed reduction mechanism 41. The sun gear 411 meshes with a plurality of planet gears 412 arranged at equal intervals, and each planet gear 412 meshes with a ring gear 413 fixed to the first housing 6 ′ by a connecting pin 23.

The second planetary gear reduction mechanism 42 is arranged on the same axis O as the first planetary gear reduction mechanism 41, and is arranged closer to the output shaft 5'side than the first planetary gear reduction mechanism 41. There is.

The sun gear 421 has a substantially cylindrical gear portion 4211 having helical teeth formed on the outer peripheral surface thereof and a plurality of cylindrical peripheral surfaces having different diameters, and the smallest diameter portion is the center of the gear portion 4211. It has a fitting portion 4213 that is fitted into the hole 4212 by press fitting. The gear portion 4211 meshes with a plurality of planet gears 422 arranged at equal intervals, while the fitting portion 4213
It is connected to the planetary gear 412 of the first planetary gear reduction mechanism 41 by the pin member 24 at the maximum diameter portion. Thereby, the planetary gear 41 of the first planetary gear reduction mechanism 41
2 rotates (revolves) around the position of the sun gear 421, so that the gear portion 421 is integrated with the fitting portion 4213.
1 rotates (rotates).

The planet gear 422 is rotatably supported by the output shaft 5'via a bearing 18 'by a pin member 17', and the planet gear 412 rotates (revolves) around the position of the sun gear 421. Causes the output shaft 5'to rotate (rotate).

With the above configuration, the output of the motor M is decelerated by the planetary gear reduction mechanism 41, 42 at a predetermined reduction ratio and then output.

The planetary gear reducer 1'having the above structure
By setting the meshing ratio and the like for each of the gears 411 to 413 and 421 to 423, as in the first embodiment, the quietness of the reduction gear 1 ′ can be improved.

[0057]

As described above, the sun gear integrally connected to the input shaft, the plurality of planet gears that revolve around the sun gear while revolving around the sun gear, and the planet gears mesh with each other and are fixed to the housing. And a ring gear, and an output shaft that rotatably supports the rotation shafts of the planet gears and that rotates about the rotation shaft of the sun gear by the revolution of the planet gears, and the module of each gear is in the range of 0.3 to 1. In a planetary gear reducer having a planetary gear mechanism in which the number of teeth is set to 72 or less, each gear is formed as a helical tooth, and the sun gear and the planetary gear mesh with each other. By setting the sum of the front meshing ratio and the overlapping meshing ratio in the range of 2.0 to 3.5, the meshing ratio becomes larger than that of the tooth immediately, so while avoiding an increase in the size of the reduction gear, Than There it is possible to ensure the quietness.

Further, according to the present invention, 0.016 to 0.034 per tooth width of 25 mm is provided in at least the planet gear.
By providing the crowning of mm, the quietness of the planetary gear reducer can be further improved.

Further, according to the present invention, the cutting amount is gradually reduced toward a predetermined position which is separated from the tip of the tooth in the height direction of the tooth by a predetermined distance, and the distance is 0.25 to 0.25.
0.48 mm, the cutting amount at the tip of the tooth is 0.00
The quietness of the planetary gear reducer can be further improved by setting the tooth tips in the range of 6 to 0.012 mm.

Further, according to the present invention, the ring gear is a positive shift gear that is gear-shifted with a shift coefficient of +0.3 to +1.5, whereby the planetary gear and the ring gear mesh with each other, and the quietness of the planetary gear reducer is reduced. Can be further improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of a planetary gear speed reducer and a drive device using the same according to the present invention.

FIG. 2 is an explanatory diagram of crowning.

FIG. 3 is an explanatory diagram for explaining a crowning amount.

FIG. 4 is an explanatory diagram of tooth tip correction.

FIG. 5 is an explanatory diagram of dislocations.

FIG. 6 is a diagram showing a configuration of a modified example of the planetary gear reducer according to the present invention in which two planetary gear mechanisms are arranged side by side in the axial direction.

FIG. 7 is an explanatory diagram of an axial force generated in a helical gear.

[Explanation of symbols]

1 Planetary gear reducer 2 housing 3 input axes 32 connection 33 Fitting part 4 Planetary gear mechanism 5 output shafts 51 Column 52 Extension 14 sun gear 141 gear 142 Fitting part 15 planetary gears 151 through hole 16 ring gear 17 pin member M motor Mb motor shaft

Claims (6)

[Claims] 1. A sun gear integrally connected to an input shaft, a plurality of planet gears that revolve around the sun gear while revolving around the sun gear, a ring gear fixed to the housing that meshes with the planet gears, and each planet. An output shaft that supports the rotation shaft of the gear and that rotates about the rotation shaft of the sun gear by the revolution of the planetary gear, and the module of each gear is set in the range of 0.3 to 1, and A planetary gear speed reducer including a planetary gear mechanism in which a ring gear has 72 or less teeth. The sum of the meshing ratio and the overlapping meshing ratio is 2.0 to 3.
A planetary gear reducer characterized by being set in a range of 5. 2. The planetary gear reducer according to claim 1, wherein the twist angles of the teeth of the sun gear and the planet gears are set in a range of 10 ° to 20 °. 3. The planetary gear speed reducer according to claim 1, wherein at least the planetary gear is crowned. 4. The tooth thickness of at least the cutting edge portion of the planetary gear is set to be substantially equal to the tooth thickness defined by the involute curve when a load is applied, than the tooth thickness defined by the involute curve when no load is applied. The planetary gear reducer according to claim 1, wherein the planetary gear reducer is thin. 5. The planetary gear reducer according to claim 1, wherein the ring gear is a positive shift gear. 6. The planetary gear reducer according to claim 1 and a motor are combined, and the rotation of the output shaft of the motor is reduced at a predetermined reduction ratio via the planetary gear reducer. Output device