JP2022032384A - Planetary gear device - Google Patents

Abstract

To reduce friction loss between an external gear and an internal gear.SOLUTION: A planetary gear device 1 comprises an external gear 11 and an internal gear 31G. On at least one tooth surface of the external gear 11 and the internal gear 31G, DLC coatings 111, 311G having a surface hydrogen content of 10 at% or less are provided, and lubricant T interposed in a meshing part between the external teeth of the external gear 11 and the internal teeth of the internal gear 31G contains fatty acid ester-based ashless friction modifier and/or aliphatic amine-based ashless friction modifier.SELECTED DRAWING: Figure 2

Description

The present invention relates to a planetary gear device.

Conventionally, in a wave gear device, which is a kind of planetary gear device, a DLC (Diamond Like Carbon) coating is formed on the surface of an external gear and the surface of an internal gear to reduce friction loss during driving (). For example, see Patent Document 1).

International Publication No. 2019/155831

However, in the above-mentioned prior art, there is no consideration for an appropriate lubricant between the external gear and the internal gear, and it is not possible to sufficiently reduce the friction between the external gear and the internal gear during driving. There was room for improvement in reducing friction loss.
The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the friction loss between the external gear and the internal gear.

The present invention is a planetary gear device including an external gear and an internal gear, wherein the surface hydrogen content of the external gear and at least one of the internal gears is 10 at% or less. A DLC coating is provided, and the lubricant interposed in the meshing portion between the outer teeth of the external gear and the internal teeth of the internal gear is a fatty acid ester-based ashless friction modifier and / or an aliphatic amine-based lubricant. The configuration includes an ashless friction modifier.

According to the present invention, it is possible to reduce the friction loss between the external gear and the internal gear.

It is sectional drawing in the axial direction which shows the bending meshing type gear apparatus which concerns on this embodiment. FIG. 3 is an enlarged cross-sectional view of the meshing portion between the external gear and the first internal gear as viewed from the axial direction. It is a diagram which obtained the relationship between the output rotation speed and the loss rate of an eccentric swing type gear device which is a planetary gear device.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Structure of flexible meshing gear device]
FIG. 1 is an axial sectional view showing a flexure meshing gear device 1 as a planetary gear device according to the present invention.
As shown in this figure, the flexure meshing gear device 1 is a tubular flexure meshing gear device, and has a oscillating body shaft 10, an external gear 11, and a first internal gear 31G as an internal gear. A second internal gear 32G, a vibration exciter bearing 12, a casing 33, a first cover 34, and a second cover 35 are provided.

The exciter shaft 10 is a hollow tubular shaft that rotates around the rotation shaft O1, and has a non-circular (for example, elliptical) outer shape of the cross section perpendicular to the rotation shaft O1 and a vibrating body 10A. It has shaft portions 10B and 10C provided on both sides in the axial direction of 10A. The ellipse is not limited to a geometrically exact ellipse and includes a substantially ellipse. The shaft portions 10B and 10C are shafts having a circular outer shape in a cross section perpendicular to the rotation shaft O1.
In the following description, the direction along the rotation axis O1 is referred to as "axial direction", the direction perpendicular to the rotation axis O1 is referred to as "diametrical direction", and the rotation direction centered on the rotation axis O1 is referred to as "circumferential direction". Further, in the axial direction, the side (left side in the figure) that is connected to the external driven member and outputs the decelerated motion to the driven member is called the "output side", and is the side opposite to the output side (the output side). The right side in the figure) is called the "anti-output side".

The external gear 11 has flexibility and is a cylindrical member centered on the rotating shaft O1, and has teeth on the outer periphery thereof.

The first internal gear 31G and the second internal gear 32G rotate around the exciter shaft 10 about the rotation shaft O1. The first internal gear 31G and the second internal gear 32G are provided side by side in the axial direction and mesh with the external gear 11. Specifically, one of the first internal gear 31G and the second internal gear 32G meshes with the tooth portion on one side of the center of the external gear 11 in the axial direction, and the other meshes with the tooth portion on one side in the axial direction of the external gear 11. It meshes with the tooth on the other side of the center.
Of these, the first internal gear 31G is configured by providing internal teeth at the corresponding portion of the inner peripheral portion of the first internal gear member 31. On the other hand, the second internal gear 32G is configured by providing internal teeth at a corresponding portion of the inner peripheral portion of the second internal gear member 32.

The oscillating body bearing 12 is, for example, a roller bearing, and is arranged between the oscillating body 10A and the external gear 11. The exciter 10A and the external gear 11 can rotate relative to each other via the exciter bearing 12.
The oscillating body bearing 12 has an outer ring 12a fitted inside the external gear 11, a plurality of rolling elements (rollers) 12b, and a cage 12c for holding the plurality of rolling elements 12b.
The plurality of rolling elements 12b are arranged in the radial direction of the first internal gear 31G, and are arranged in the radial direction of the rolling elements 12b of the first group arranged in the circumferential direction and the second internal gear 32G. It has a second group of rolling elements 12b arranged in the circumferential direction. These rolling elements 12b roll with the outer peripheral surface of the oscillator 10A and the inner peripheral surface of the outer ring 12a as rolling surfaces. Two outer rings 12a having the same shape are provided side by side in the axial direction corresponding to the arrangement of the plurality of rolling elements 12b. The oscillating body bearing 12 may have an inner ring separate from the oscillating body 10A.

Spacer rings 41 and 42 are provided on both sides of the oscillating body bearing 12 and the external gear 11 in the axial direction as a restricting member that abuts on them and regulates their axial movement.

The casing 33 is connected to the first internal gear member 31 by a bolt 51 and covers the outer diameter side of the second internal gear 32G. The casing 33 has an outer ring portion of a main bearing 38 (for example, a cross roller bearing) formed on the inner peripheral portion, and rotatably supports the second internal gear member 32 via the main bearing 38. There is. When the flexible meshing gear device 1 is connected to an external mating device, the casing 33 and the first internal gear member 31 are co-tightened to the mating device.

The first cover 34 is connected to the first internal gear member 31 by a bolt 52, and covers the meshing portion between the external gear 11 and the first internal gear 31G from the counter-output side in the axial direction. A bearing 36 (for example, a ball bearing) is arranged between the first cover 34 and the shaft portion 10B of the exciter shaft 10, and the first cover 34 uses the exciter shaft 10 via the bearing 36. Supports rotatably.

The second cover 35 is connected to the second internal gear member 32 by a bolt 53, and covers the meshing portion between the external gear 11 and the second internal gear 32G from the output side in the axial direction. A bearing 37 (for example, a ball bearing) is arranged between the second cover 35 and the shaft portion 10C of the exciter shaft 10, and the second cover 35 uses the exciter shaft 10 via the bearing 37. Supports rotatably. When the flexure meshing gear device 1 is connected to an external mating device, the second cover 35 and the second internal tooth gear member 32 are connected to the driven member of the mating device by co-tightening to reduce the rotation. Output to the driven member.

Further, the flexure meshing gear device 1 includes oil seals 43, 44, 45 for sealing and O-rings 46, 47, 48.
The oil seal 43 is arranged between the shaft portion 10B of the exciter shaft 10 and the first cover 34 at the end portion on the counter-output side in the axial direction, and suppresses the outflow of the lubricant to the counter-output side. The oil seal 44 is arranged between the shaft portion 10C of the exciter shaft 10 and the second cover 35 at the end portion on the output side in the axial direction, and suppresses the outflow of the lubricant to the output side. The oil seal 45 is arranged between the casing 33 and the second internal gear member 32, and suppresses the outflow of the lubricant from this portion.
The O-rings 46, 47, 48 are between the first internal gear member 31 and the first cover 34, between the first internal gear member 31 and the casing 33, and between the second internal gear member 32 and the second cover. Each is provided between the 35 and 35, and suppresses the movement of the lubricant between them.

[Measures to reduce friction loss between external gears and internal gears]
A measure for reducing friction loss in the meshing portion between the external gear 11 and the first internal gear 31G as the internal gear will be described.
FIG. 2 is an enlarged cross-sectional view of the meshing portion between the external gear 11 and the first internal gear 31G as viewed from the axial direction.

The above-mentioned external gear 11 uses structural alloy steel as a general metal material used for gears as a base material, and for example, SNCM (nickel chrome molybdenum steel) as a base material. The first internal gear 31G and the second internal gear 32G use structural alloy steel as a general metal material used for gears as a base material, and for example, SCM (chromoly molybdenum steel) as a base material. .. The base material of the external gear 11 has a higher hardness than the base material of the first internal gear 31G and the second internal gear 32G.

Then, as shown in FIG. 2, DLC (Diamond Like Carbon) having a hydrogen content of 10 at% or less is formed on the surface (surface of the tooth portion) of the meshing portion of the external gear 11 with respect to the first internal gear 31G. A coating 111 (so-called hydrogen-free DLC coating) is formed.
Further, a DLC coating 311G (hydrogen-free DLC coating) having a hydrogen content of 10 at% or less is also formed on the surface (surface of the tooth portion) of the meshing portion of the first internal gear 31G with respect to the external gear 11. There is.
Further, the lubricant T is interposed between the DLC coating 111 of the external gear 11 and the DLC coating 311G of the first internal gear 31G.

The lower the hydrogen content of the DLC film, the greater the effect of reducing friction. Therefore, the DLC coatings 111 and 311G have a hydrogen atom content of 10.0 at% or less, more preferably a hydrogen atom content of 1.0 at% or less, and further, an aC-based (amorphous carbon-based) DLC that does not contain hydrogen. It is preferable to use a coating.
Further, the film thickness of the DLC coatings 111 and 311G is preferably formed in the range of 0.3 to 1.5 [μm]. These DLC coatings 111 and 311G are formed by various PVD methods, for example, an arc ion plating method.

On the other hand, the surface roughness Ra of each of the meshing portions of the external gear 11 and the first internal gear 31G before the DLC coatings 111 and 311G are formed shall be 0.08 [μm] or less. Is preferable. When the surface roughness Ra exceeds 0.08 [μm], the protrusions caused by this surface roughness cause local sliding on the DLC coatings 111 and 311G, and the coating is likely to be cracked. By setting the surface roughness Ra to 0.08 [μm] or less, cracking of the DLC coatings 111 and 311G can be suppressed and protection can be achieved for a long period of time. It is more preferable that the surface roughness Ra of the base metal is 0.03 [μm] or less.
Although no DLC film is formed on the surface of the meshing portion of the second internal gear 32G with respect to the external gear 11, the surface of the meshing portion also has a surface roughness Ra of 0.08 [μm] or less, and further. , 0.03 [μm] or less is preferable.

The lubricant T interposed between the DLC coatings 111 and 311G is a fatty acid ester-based ashless friction modifier using what is normally used as a lubricating oil base oil such as mineral oils, synthetic oils, fats and oils and mixtures thereof. It contains one or both of an aliphatic amine-based ashless friction modifier.
The fatty acid ester-based ashless friction modifier and / or the aliphatic amine-based ashless friction modifier includes fatty acid esters having linear or branched hydrocarbon groups having 6 to 30 carbon atoms, fatty acid amine compounds, and fatty acid amine compounds. Examples thereof include arbitrary mixtures thereof. A large friction reduction effect can be obtained by setting the carbon number in the range of 6 to 30.
The content of the fatty acid ester-based ashless friction modifier and / or the aliphatic amine-based ashless friction modifier contained in the lubricant T is preferably 0.05 to 3.0% based on the total amount of the lubricating oil composition. .. If the content is less than 0.05%, the friction reducing effect becomes small, and if it exceeds 3.0%, precipitation is likely to occur.

Further, the lubricant T contains polybutenyl succinimide and / or a derivative thereof as a cleaning agent. The content of polybutenyl succinimide and / or its derivative is preferably 0.1 to 15%, and if it is less than 0.1%, the cleaning effect is reduced, and if it exceeds 15%, the cleaning effect commensurate with the content is not increased. Anti-emulsifying properties can be exacerbated.

Further, the lubricant T contains zinc dithiophosphate. Zinc dithiophosphate has antioxidant ability, corrosion prevention ability, load-bearing performance improving ability, wear prevention ability and the like. The content of the zinc dithiophosphate is preferably 0.1% or less based on the total amount of the lubricating oil composition and the phosphorus element equivalent amount. If it exceeds this, the friction reducing effect may be reduced.

[Deceleration operation of flexible meshing gear device]
Subsequently, the deceleration operation of the flexure meshing gear device 1 will be described.
When the exciter shaft 10 is rotationally driven by a drive source such as a motor, the motion of the exciter 10A is transmitted to the external gear 11. At this time, the external gear 11 is restricted to a shape along the outer peripheral surface of the exciter 10A, and is bent into an elliptical shape having a long axis portion and a short axis portion when viewed from the axial direction. Further, the external gear 11 meshes with the fixed first internal gear 31G at a long shaft portion. Therefore, the external gear 11 does not rotate at the same rotation speed as the exciting body 10A, and the exciting body 10A rotates relatively inside the external gear 11. Then, with this relative rotation, the external gear 11 bends and deforms so that the major axis position and the minor axis position move in the circumferential direction. The period of this deformation is proportional to the rotation period of the exciter shaft 10.

When the external gear 11 bends and deforms, its long axis position moves, so that the meshing position between the external gear 11 and the first internal gear 31G changes in the rotational direction. Here, for example, assuming that the number of teeth of the external gear 11 is 100 and the number of teeth of the first internal gear 31G is 102, the external gear 11 and the first internal gear 31G are engaged every time the meshing position goes around. The meshing teeth of the teeth are displaced, which causes the external tooth gear 11 to rotate (rotate). With the above number of teeth, the rotational motion of the exciter shaft 10 is decelerated at a reduction ratio of 100: 2 and transmitted to the external gear 11. In this case, the reduction ratio is "50".

On the other hand, since the external gear 11 also meshes with the second internal gear 32G, the meshing position between the external gear 11 and the second internal gear 32G also changes in the rotation direction due to the rotation of the exciter shaft 10. .. Here, assuming that the number of teeth of the second internal gear 32G and the number of teeth of the external gear 11 are the same, the external gear 11 and the second internal gear 32G do not rotate relatively, and the external teeth The rotational movement of the gear 11 is transmitted to the second internal tooth gear 32G at a reduction ratio of 1: 1. As a result, the rotational movement of the exciter shaft 10 is decelerated at a reduction ratio of 100: 2 and transmitted to the second internal gear member 32 and the second cover 35, and this rotational movement is output to the driven member.

[Technical effect of this embodiment]
In the deflection meshing type gear device 1, the meshing portion of the external gear 11 with respect to the first internal gear 31G and the second internal gear 32G and the tooth surface of the first internal gear 31G with respect to the external gear 11 DLC coatings 111,311G having a hydrogen content of 10 at% or less are provided on the tooth surface, which is a portion, and is interposed between the external teeth of the external gear 11 and the internal teeth of the first internal gear 31G. The lubricant T is configured to contain a fatty acid ester-based ashless friction modifier and / or an aliphatic amine-based ashless friction modifier.
The DLC film has high hardness, is excellent in heat resistance and wear reduction effect, and when the hydrogen content is 10 at% or less, a further dramatic wear reduction effect can be obtained.
Further, since the lubricant T contains a fatty acid ester-based ashless friction modifier and / or an aliphatic amine-based ashless friction modifier, and further contains a polybutenyl succinate imide and / or a derivative thereof. A high friction reducing effect can be obtained.
Therefore, the DLC coatings 111 and 311G having a hydrogen content of 10 at% or less are formed on the meshing portions of both the external gear 11 and the first internal gear 31G, and the lubricant T is interposed between them. It is possible to synergistically obtain an extremely high friction reduction effect, and it is possible to dramatically reduce the loss due to friction between the external gear 11 and the first internal gear 31G when the flexible meshing gear device 1 is driven. It will be possible.
Furthermore, the friction reduction effect of the DLC coating having a hydrogen content of 10 at% or less and the lubricant T can extremely reduce the amount of wear on both the external gear 11 and the first internal gear 31G, so that meshing due to wear can be achieved. It is possible to suppress errors and continuously perform high-precision operation for a long period of time.

Further, in the flexure meshing type gear device 1, a DLC coating 311G is provided on the first internal gear 31G having a different number of teeth from the external gear 11, and the second internal gear 32G having the same number of teeth as the external gear 11 is provided. Is not provided with a DLC coating.
Generally, in a flexure meshing gear device, the first internal gear that rotates relative to the external gear is compared to the second internal gear that does not rotate relative to the external gear. Therefore, wear is likely to occur.
However, as described above, by providing the DLC coating 311G on the first internal gear 31G, the friction of the first internal gear 31G is reduced and the amount of wear thereof is reduced, so that the external gear caused by the wear is reduced. The difference between the meshing error between the 11 and the first internal gear 31G and the meshing error between the external gear 11 and the second internal gear 32G is reduced, and the deflection meshing gear device 1 reduces the difference in meshing error over a long period of time. It is possible to accurately transmit the deceleration operation to the driven member side.
Further, by minimizing the formation region of the hydrogen-free DLC film, it is possible to reduce the film formation cost.

FIG. 3 is a diagram showing the relationship between the output rotation speed and the loss rate of the eccentric swing type gear device which is a planetary gear device.
In FIG. 3, the solid line shows the outer circumference of the eccentric body provided on the eccentric body shaft, the outer circumference of the roller of the eccentric body bearing, the outer circumference of the outer pin constituting the inner tooth of the internal gear, and the rotation rotation of the external gear. The characteristics of the eccentric swing type gear device in which a hydrogen-containing DLC film is formed on the outer periphery of each of the inner pin and the inner roller are shown. The characteristics of the device are shown.
The eccentric swing type gear device without the DLC coating has a high loss rate in the low speed range where the output rotation speed is less than 5 [rpm], but the eccentric swing type gear device with the DLC coating has the same low speed. It is remarkable that the loss rate is kept low in the region.

The above-mentioned flexure meshing gear device 1 uses a hydrogen-free DLC film having an excellent friction-reducing effect among the DLC films, and even when such a hydrogen-free DLC film is used, the output rotation speed is high. It can be easily inferred that the loss rate can be kept low in the low speed range where is less than 5 [rpm].
Therefore, it can be said that the planetary gear device according to the present invention is suitable when the output rotation speed is 5 [rpm] or less.

[others]
Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.
For example, in the above-mentioned bending meshing type gear device 1, a configuration is exemplified in which hydrogen-free DLC coatings 111 and 311G are formed on the meshing portions (tooth surfaces) of the external tooth gear 11 and the first internal tooth gear 31G, respectively. , The meshing portion (tooth surface) on the external gear 11 side or the meshing portion (tooth surface) on the first internal gear 31G side may be formed.
Further, in the flexure meshing type gear device 1, it is exemplified that a hydrogen-free DLC coating 111 is formed in the meshing portion of the external gear 11 with respect to the first internal gear 31G, but the second inner of the external gear 11 is illustrated. A hydrogen-free DLC coating may also be formed on the meshing portion with respect to the tooth gear 32G.
Further, a hydrogen-free DLC coating may be formed on the meshing portion (tooth surface) of the second internal gear 32G with respect to the external gear 11.

Further, for the external gear 11, as shown in FIG. 1, a hydrogen-free DLC coating may be formed on both end faces 11a and the inner circumference 11b in the axial direction. That is, a hydrogen-free DLC film may be formed on the entire external gear 11.
Further, a hydrogen-free DLC coating may be formed on the surface (including both the outer peripheral surface and the end surface in the central axial direction) of the rolling element of the main bearing 38 made of the cross roller bearing.
It is preferable to interpose the same lubricant as the lubricant T between the surface on which the hydrogen-free DLC film is formed and the sliding surface thereof.

In this way, each member on which the hydrogen-free DLC film is formed can obtain a friction reduction effect, reduce friction loss and improve wear resistance, and damage the sliding surface of the mating member. It is possible to suppress the occurrence of wear. Further, the effect of reducing the friction loss is particularly remarkable when the output rotation speed is 5 [rpm] or less.

Further, in the above embodiment, the cylindrical flexure meshing gear device is exemplified as the planetary gear device, but the present invention can be applied to any planetary gear mechanism having an internal gear and an external gear. Is.
For example, the present invention can also be applied to a cup-type or top-hat-type flexible meshing gear device, further, a center crank-type eccentric swing-type speed reducer, and two or more shafts having an eccentric body. It can also be applied to so-called distribution type eccentric swing type reduction gears and simple planetary gears arranged offset from the axis of the reduction gear.

1 Flexion meshing gear device (planetary gear device)
10 Exciting body shaft 10A Exciting body 11 External gear 11a Both end faces 11b Inner circumference 31G First internal gear (internal gear)
32G 2nd internal gear (internal gear)
111,311G DLC film O1 rotary shaft T lubricant

Claims (6)

A planetary gear device equipped with external gears and internal gears.
A DLC coating having a surface hydrogen content of 10 at% or less is provided on at least one tooth surface of the external gear and the internal gear.
A planet in which the lubricant interposed in the meshing portion between the outer teeth of the external gear and the internal teeth of the internal gear contains a fatty acid ester-based ashless friction modifier and / or an aliphatic amine-based ashless friction modifier. Gear device. The planetary gear device according to claim 1, wherein the lubricant contains polybutenyl succinimide and / or a derivative thereof. Equipped with a oscillating body,
The external tooth gear is deformed and deformed by the oscillating body, and is deformed.
The internal gear has a first internal gear and a second internal gear, and the internal gear has a first internal gear and a second internal gear.
The planetary gear device is a deflection mesh gear device in which the number of teeth of the first internal gear and the external gear are different, and the number of teeth of the second internal gear and the external gear is the same.
The planetary gear device according to claim 1 or 2, wherein the first internal gear and the external gear are provided with the DLC coating, and the second internal gear is not provided with the DLC coating. The planetary gear device according to any one of claims 1 to 3, wherein the DLC coating is provided on both end faces in the axial direction of the external gear. The planetary gear device according to any one of claims 1 to 4, wherein the DLC coating is provided on the inner circumference of the external gear. The planetary gear device according to any one of claims 1 to 5, which is used at an output rotation speed of 5 [rpm] or less.

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