JP2009041747A - Power transmission device and sliding part structure for power transmission device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power transmission device suppressing transmission loss and improving transmission efficiency by reducing friction and wear between sliding members, and a sliding part structure for the power transmission device. <P>SOLUTION: The power transmission device 100 has a sliding part in which the pair of sliding members are slid each other. At least one of two opposing surfaces of the pair of sliding members has surface roughness formed by predetermined roughness processing and a carbon film to which a metallic element is added and which is formed on the surface roughness. A lubricant including Mo and S as components is arranged between the two opposing sliding surfaces. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a power transmission device that outputs input power via a plurality of sliding members, and a sliding part structure of the power transmission device.

  Conventionally, in order to reduce the power transmission loss of the power transmission device, the following three methods have been considered in order to reduce the friction and wear of the sliding member.

(A) Use a lubricant.
(B) The contact surface is coated by plating, vapor deposition or the like.
(C) Combine (a) and (b).

  The lubricant (a) is roughly classified into three types, that is, lubricant (liquid form such as oil), grease (semi-solid form), and solid lubricant, and each is properly used depending on the application. In general, lubricating oil is widely used and widely used for bearings, gears, engines, cutting and the like. On the other hand, grease is used for a bearing of a speed reducer such as an intermeshing planetary gear speed reducer taking advantage of its non-fluid feature (for example, Patent Document 1). Solid lubricants are used in environments where lubricating oils and greases cannot be used, or as additives for lubricating oils and greases. Use environments include vacuum, high / low temperature, and corrosive environments. Can be mentioned.

JP 2001-187945 A

  However, in the above three methods, the actual situation is that the friction of the sliding member has not been sufficiently reduced.

  For example, the above-mentioned (a) to (c), and (a) and (b) that do not take any countermeasures are treated as (d), and the surface of the ball used as the standard sample is subjected to surface treatment under each condition. These friction coefficients were measured with a tribometer by the ball-on-disk method at a sliding distance of 100 m (FIG. 9), and the results are shown in FIG. 10 together with the surface treatment conditions. In addition, the surface roughness by surface roughness is not formed in the foundation | substrate surface-treated here.

  As is apparent from this result, the friction coefficient μ is about 0.08 in the condition (a), about 0.16 in the condition (b), about 0.08 in the condition (c), and about 0 in the condition (d). .94, and by using a lubricant, the friction coefficient can be lowered to about 0.08, but conversely, it can be confirmed that it was the limit.

  The present invention has been made to solve the above-described conventional problems. In the power transmission device, the power transmission device reduces friction and wear between sliding members, thereby suppressing transmission loss and improving transmission efficiency. It is another object of the present invention to provide a sliding part structure for a power transmission device.

  The present invention is a power transmission device having a sliding portion in which a pair of sliding members slide relative to each other, wherein at least one of two opposing sliding surfaces of the pair of sliding members has a predetermined roughness. A surface roughness formed by processing, and a carbon-based film formed on the surface roughness to which a metal element is added, and Mo (molybdenum) and S between the two facing sliding surfaces. The problem is solved by providing a lubricant containing (sulfur) as a component.

  In the present invention, at least one of the two opposing sliding surfaces of the sliding member of the power transmission device has a surface roughness generated by the roughness processing, and a metal element is added thereon. Have a carbon-based coating. With this surface roughness, it is possible to form a carbon-based film that is excellent in wear resistance and lubricity to which a metal element has been added, and it is possible to prevent the carbon-based film from disappearing even when worn. Moreover, the effect of the protection of the surface of the base | substrate by a carbon-type film and abrasion resistance can also be acquired. Furthermore, since a lubricant containing Mo and S as components is disposed between the sliding surfaces facing each other of the sliding member, it is easy to attract Mo and S to the sliding surface by the metal element in the carbon-based coating, and lubrication A highly functional molybdenum disulfide film (hereinafter referred to as a Mo-S film) can be formed. In addition, even if the wear of the sliding surface is advanced due to the surface roughness of the base due to the roughness processing, the carbon-based film to which the metal element is added and the lubricant containing Mo and S remain, so that the Mo-S film is formed. It can be maintained for a long time, and practical friction reduction is possible.

  Note that the range of the surface roughness is preferably, for example, an average roughness (Ra) of 0.03 μm to 0.5 μm, and the Mo—S film can be held for a long time.

  According to the present invention, friction is reduced in the sliding portion of the power transmission device, and highly efficient power transmission is possible.

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

[First Embodiment]
A first embodiment according to the present invention will be described with reference to FIGS. 1 is a cross-sectional view of a power transmission device according to the present embodiment, FIG. 2 is an enlarged view of a sliding part structure surrounded by a broken line of the power transmission device of FIG. 1, and FIG. FIG. 4 is a table showing the results of FIG. 3, and FIG. 5 is a schematic diagram showing the position of the wear surface as an observation surface by an electron beam microanalyzer (EPMA). 6 is a display screen showing the result of analyzing the worn surface shown in FIG. 5 by EPMA, and FIG. 7 is a graph showing the friction coefficient, efficiency, and temperature measurement results.

<Configuration of First Embodiment>
First, the configuration of an intermeshing planetary gear reducer that is a power transmission device according to the present embodiment will be described with reference to FIGS. 1 and 2. The intermeshing planetary gear speed reducer 100 includes an input shaft 102, eccentric bodies 110 and 112 integrated with the input shaft 102, and external gears 126 and 128 that swing and rotate by the eccentric bodies 110 and 112. An internal gear 136 having internal teeth with which the external gears 126 and 128 are internally meshed, and an internal pin 148 that is arranged on the outer side in the axial direction of the external gears 126 and 128 and extracts the rotation components of the external gears 126 and 128. And a flange body 152 coupled to the. Hereinafter, each component will be described in detail.

  The input shaft 102 is supported by a pair of bearings 104 and 106 as shown in FIG. The bearing 104 is supported by the input stage cover 144, and the bearing 106 is supported by the inner surface of the flange body 152 that is integral with the output shaft 154.

  The eccentric bodies 110 and 112 are integrated with the input shaft 102 between the bearings 104 and 106 as shown in FIG. The eccentric bodies 110 and 112 are each offset by 180 degrees in the eccentric phase. As shown in FIG. 2, the eccentric bodies 110 and 112 include groove side surfaces 110a and 112a that receive the rollers 116 and 122 of the roller bearings 114 and 120 disposed between the external gears 126 and 128, and groove bottom surfaces 110b and 112b. With. Further, the roller bearings 114 and 120 are constituted by retainers 118 and 124 that hold the positions of the rollers 116 and 122, respectively. Therefore, the side surfaces 116a and 122a of the rollers (first members) 116 and 122 and the groove side surfaces 110a and 112a of the eccentric bodies (second members) 110 and 112, which are surfaces facing the side surfaces 116a and 122a, are slidable surfaces. Is formed. For this reason, the surface treatment which concerns on this embodiment mentioned later is performed with respect to the two sliding surfaces which the said sliding member opposes.

  As shown in FIG. 1, the external gears 126 and 128 are fitted to the outer periphery of the eccentric bodies 110 and 112 via roller bearings 114 and 120. The external gears 126 and 128 respectively have a plurality of inner pin holes 130 and 132 penetrating in the axial direction, and the inner roller 150 is loosely fitted in the inner pin holes 130 and 132. In other words, the external gears 126 and 128 are oscillated and rotated by the rotation of the eccentric bodies 110 and 112, and are internally meshed with the internal gear 136. In the present embodiment, the external gears 126 and 128 have the same number of teeth with a slight difference (about 1 to 3) from the number of teeth of the internal gear 136 and have the same shape, thereby ensuring a power transmission capacity. It is said. The spacer 134 is inserted between the external gear 126 and the external gear 128 so that the interval is constant.

  The main body of the internal gear 136 is integrated with the casing 142 as shown in FIG. A plurality of outer pins 140 and an outer roller 138 inserted on the outer periphery of the outer pin 140 form a tooth shape, and are in mesh with the external gears 126 and 128. As shown in FIG. 2, the outer pin 140 is rotatably held by the main body of the internal gear 136, the input stage cover 144, and the output stage cover 146. Further, the outer roller 138 is also in contact with the flange body 152 and the input stage cover 144. For this reason, by the swinging rotation of the external gears 126 and 128, the inner peripheral surface 138a of the outer roller (first member) 138 and the outer pin (second member) 140, which is the surface facing the inner peripheral surface 138a. A sliding portion having the outer peripheral surface 140a as a sliding surface is formed. At the same time, the outer roller (first member) is a sliding portion having a side surface 138b of the outer roller (first member) 138 and an inner surface 144b of the input stage cover (second member) 144, which is a surface facing the side surface 138b. Member) 138 and the outer roller (first member) 138, the sliding portion having the sliding surface of the side surface 138b of the output stage cover (second member) 146, which is the surface facing the side surface 138b, and the inner surface 146a. Sliding portions having sliding surfaces on the side surface 138b and the inner surfaces 136b and 136d of the main body of the internal gear (second member) 136, which are surfaces facing the side surface 138b, are formed.

  Further, the both ends holding surface 140b of the outer pin (first member) 140 and the internal gear (second member) which is the surface facing the both ends holding surface 140b by sliding rotation around the outer pin 140 of the outer roller 138. ) A sliding portion having the inner surfaces 136a and 136c of the main body 136 as sliding surfaces, the both-end holding surface 140b of the outer pin (first member) 140, and the input stage cover (first step) which is the surface facing the both-end holding surface 140b. 2 member) An input stage cover (second member) which is a sliding portion having the inner surface 144c of the 144 as a sliding surface, both end holding surfaces 140c of the outer pin (first member) 140, and a surface facing the both end holding surfaces 140c. ) A sliding portion having an inner surface 144d of 144 as a sliding surface, both end holding surfaces 140b of the outer pin (first member) 140, and an output stage cover (second member) 146 which is a surface facing the both end holding surfaces 140b. Inner surface 146b of A sliding portion as a sliding surface, and both end holding surfaces 140c of the outer pin (first member) 140 and an inner surface 146c of the output stage cover (second member) 146 which is a surface facing the both end holding surfaces 140c. Sliding portions serving as sliding surfaces are respectively formed. For this reason, the surface treatment which concerns on this embodiment mentioned later is performed with respect to the two sliding surfaces which the said sliding member opposes.

  As shown in FIG. 1, the flange body 152 is disposed on the outer side in the axial direction of the external gear 128, and an inner pin 148 is connected and fixed thereto. A pipe-shaped inner roller 150 is fitted on the outer periphery of the inner pin 148, and the inner roller 150 is loosely fitted in the inner pin holes 130 and 132 of the external gears 126 and 128. Therefore, the internal pin 148 can extract the rotation components of the external gears 126 and 128 and the internal gear 136. As shown in FIG. 2, the inner peripheral surface 150a of the inner roller (first member) 150 and the inner pin (second member) which is the surface facing the inner peripheral surface 150a by the swinging rotation of the external gears 126 and 128. A sliding portion having the outer peripheral surface 148a of 148 as a sliding surface is formed. At the same time, a sliding portion having a sliding surface on the side surface 150b of the inner roller (first member) 150 and the inner surface 144a of the input stage cover (second member) 144, which is a surface facing the side surface 150b, and the inner roller (First member) Sliding portions each having a sliding surface on the side surface 150b of the 150 and the inner surface 152a of the flange body (second member) 152 which is a surface facing the side surface 150b are formed. For this reason, the surface treatment which concerns on this embodiment mentioned later is performed with respect to the two sliding surfaces which oppose the said sliding member.

  As shown in FIG. 1, the output shaft 154 is integral with the flange body 152 and supported by the output stage cover 146 via a pair of bearings 156 and 158.

<Surface treatment of the first embodiment>
The surface treatment performed on one of the two sliding surfaces in the sliding portion described above will be described.

  First, a roughness process is performed on the surface of the sliding member that is the base of the carbon-based coating. In this embodiment, shot peening is used to improve the surface of the sliding member by striking the projection material. Therefore, durability improvement by improving fatigue strength, improvement of wear resistance, improvement of impact resistance, stress corrosion This makes it possible to prevent cracking. The surface roughness in this embodiment is an average roughness Ra of about 0.07 μm. In addition, as for surface roughness, 0.03 micrometer-0.5 micrometer are preferable by average roughness Ra.

  Next, a carbon-based hard film (also referred to as a C-based hard film) that is a carbon-based film is formed (coated) on the roughened surface. In this embodiment, a film is formed by, for example, IP (ion plating). IP is a kind of physical vapor deposition (PVD) as well as a vapor deposition method, and forms a film by vapor-depositing carbon as a coating material. Since plasma is applied to the target surface during film formation, the target surface is sputtered to clean the surface and the temperature of the target surface rises, thereby increasing the adhesion strength of the coating. The film thickness of the C-based hard film in this embodiment is about 2 μm. The material of the film is not only C (carbon) but also one or more kinds of metal elements. For example, the metal element can be Cr (chromium) or W (tungsten).

  Next, a lubricant is applied (arranged) to the surface on which the C-based hard film is formed. In this embodiment, a lubricant containing Mo and S elements at the same time is used in the present embodiment. Since the Mo-S film is formed on the sliding surface where Mo and S in the lubricant component are targeted, and functions as a lubricating film (also referred to as a tribo film), the friction coefficient is reduced. In the present embodiment, grease that is easily held by each sliding portion is used as the base oil of the lubricant.

<Comparison evaluation using the surface treatment according to the first embodiment as a standard sample>
A comparative evaluation when such a surface treatment is applied to a standard sample will be described.

  The evaluation is performed by a ball-on-disk method. A 5N load is applied to the ball, which is a standard sample placed on a rotating disk, from above, and the ball slides at 25 cm / sec without rotating the ball. As shown in FIG. 3, the friction coefficient was measured up to a sliding distance of 2000 m. The ball material is bearing steel, and the disk material is tool steel.

  As shown in FIG. 4, Test Examples A, B, and C are conditions according to the present embodiment, and the result after sliding 2000 m was as follows. In Test Example A, the disk surface was coated with a C-based hard film to which Cr was added by the surface treatment according to this embodiment, and a friction coefficient μ≈0.022 was obtained. The ball is also coated with exactly the same film. In Test Example B, the disk surface was coated with a C-based hard film to which W was added by the surface treatment according to the present embodiment, and a friction coefficient μ≈0.025 was obtained. The ball is also coated with exactly the same film. In Test Example C, the disk surface was coated with a C-based hard film to which W was added by the surface treatment according to this embodiment, and a friction coefficient μ≈0.026 was obtained. The ball is not coated. In Comparative Example D, unlike the surface treatment according to the present embodiment on the disk surface, a grease containing no Mo and S was used, and a friction coefficient μ≈0.138 was obtained. The ball is not coated. In Comparative Example E, unlike the surface treatment according to the present embodiment, the disk surface was not coated at all, and a friction coefficient μ≈0.074 was obtained. The ball is not coated. In Comparative Example F, unlike the surface treatment according to this embodiment, the disk surface was coated with a C-based hard film to which no metal element was added, and a friction coefficient μ≈0.043 was obtained. The ball is not coated.

  As described above, Comparative Examples D to F do not satisfy the condition of the surface treatment according to the present embodiment, so the friction coefficient μ is higher than the results in Test Examples A to C. . That is, the C-based hard film must be present on the surface roughness by the roughness processing in the present embodiment, and it is necessary that a Cr or W metal element is added thereto. However, even if it is the C type hard film to which the metal element is added, it is shown that the effect is not obtained unless the grease to which Mo and S are added is used. From these results, it can be confirmed that the friction coefficient μ can be 0.03 or less by satisfying the roughness processing conditions, coating conditions, and lubricant conditions, which are the surface treatments according to the present invention.

  Next, elemental analysis of the worn surface of the ball shown in FIG. 5 was performed using EPMA for Test Example C after measuring the 2000 m friction coefficient with a ball-on-disk. The analysis results are shown in FIG. Note that only the condition where Mo is not added to the grease is different from Test Example C, and as a result, a ball having a friction coefficient of 0.122 is analyzed as Comparative Example G and the result is shown. In FIG. 6, an image for each analysis target element on the worn surface is displayed. That is, when there are many target elements, the wear surface is displayed brightly because there are many target atoms.

  In Comparative Example G, since only the edge of the wear surface is slightly brighter on the screen of the S atom image in FIG. 6, the presence of the S element can be confirmed locally, but it is not uniform and the Mo atom image The presence of Mo element cannot be confirmed on the screen. On the other hand, in Test Example C of the present embodiment, the wear surface is projected uniformly and brightly on each of the screens of the Mo atom image and the S atom image, so that the Mo element and the S element appear on the wear surface. It can be seen that the distribution is uniform. That is, by the surface treatment of this embodiment, even if the surface of the ball is worn, a lubricating film made of Mo-S having a high self-lubricating property is formed, and the presence of the lubricating film is effective in reducing the friction coefficient. I can confirm that there is.

<Operation of First Embodiment>
Next, the operation of the power transmission device according to this embodiment will be described with reference to FIGS.

  When power is transmitted from a power source (not shown) via the input shaft 102, the eccentric bodies 110 and 112 attached and fixed to the input shaft 102 also rotate eccentrically. Then, the rollers 116 and 122 of the roller bearings 114 and 120 are held by the retainers 118 and 124 along the grooves provided on the outer circumferences of the eccentric bodies 110 and 112, and the rollers 116 and 122 are placed on the groove bottom surfaces 110b and 112b of the eccentric body. The outer peripheral surface 122 contacts and rotates. At this time, the side surfaces 116a and 122a of the rollers 116 and 122 and the groove side surfaces 110a and 112a of the eccentric bodies 110 and 112, which are surfaces facing the side surfaces 116a and 122a, slide, but the surface treatment according to this embodiment is performed. Therefore, power is transmitted with little wear and transmission loss.

  Since the rollers 116 and 122 are guided by the outer peripheral surfaces of the eccentric bodies 110 and 112 and roll on the eccentric locus, the external gears 126 and 128 fitted through the rollers 116 and 122 swing and rotate. Here, since the external gears 126 and 128 are internally meshed with the internal gear 136 that is integral with the casing 142, the rotation of the external gears 126 and 128 is restricted, and almost only swings. Become. Then, when the external gears 126 and 128 are internally meshed with the internal gear 136, the outer roller 138 rotates around the outer pin 140. That is, the inner peripheral surface 138a of the outer roller 138 and the outer peripheral surface 140a of the outer pin 140 that is a surface facing the inner peripheral surface 138a slide. At the same time, the side surface 138b of the outer roller 138 and the inner surface 144b of the input stage cover 144 that is the surface facing the side surface 138b, the side surface 138b of the outer roller 138 and the inner surface 146a of the output stage cover 146 that is the surface facing the side surface 138b; The side surface 138b of the outer roller 138 and the inner surfaces 136b and 136d of the main body of the internal gear 136 which are the surfaces facing the side surface 138b slide, respectively. At this time, since the outer pin 140 is rotatably held, the rotation of the outer roller 138 is transmitted to the outer pin 140, and the outer pin 140 rotates to cause both end holding surfaces 140b of the outer pin 140 and the both end holding surfaces. The inner surfaces 136a and 136c of the main body of the internal gear 136, which is the surface facing 140b, the both-end holding surfaces 140b of the outer pin 140, the inner surface 144c of the input stage cover 144, which is the surface facing the both-end holding surfaces 140b, and the outer pin 140. The both end holding surface 140c and the inner surface 144d of the input stage cover 144 which is the surface facing the both end holding surface 140c, the both end holding surface 140b of the outer pin 140 and the output stage cover 146 which is the surface facing the both end holding surface 140b. Inner surface 146b, inner end holding surface 140c of outer pin 140 and inner side of output stage cover 146 which is a surface facing both end holding surfaces 140c And it is, to slide each 146c. However, since the surface treatment according to the present embodiment is performed, power is transmitted with little wear and transmission loss.

  At this time, the number of teeth of the external gears 126 and 128 and the number of teeth of the internal gear 136 (the number of the outer pins 140 and the outer rollers 138) are configured to have a slight difference (about 1 to 3). Therefore, when the eccentric bodies 110 and 112 make one rotation, the external gears 126 and 128 swing once, and at this time, they rotate by the slight difference. This rotation component is taken out to the flange body 152 through the inner pin 148 and the inner roller 150 loosely fitted in the inner pin holes 130 and 132. At this time, the inner peripheral surfaces of the inner pin holes 130 and 132 come into contact with the inner roller 150, so that the inner roller 150 rotates around the inner pin 148. Then, the inner peripheral surface 150a of the inner roller 150 and the outer peripheral surface 148a of the inner pin 148 which is a surface facing the inner peripheral surface 150a slide. At the same time, the side surface 150b of the inner roller 150 and the inner surface 144a of the input stage cover 144 that is the surface facing the side surface 150b, and the inner surface 152a of the flange body 152 that is the surface that faces the side surface 150b of the inner roller 150 and the side surface 150b. And slide. However, since the surface treatment according to the present embodiment is performed, power is transmitted with little wear and transmission loss.

  At this time, the swinging components of the external gears 126 and 128 are absorbed by loose fitting of the inner pins 148 and the inner rollers 150 with respect to the inner pin holes 130 and 132, so that only the rotation components of the external gears 126 and 128 are extracted. . Accordingly, the rotation of the input shaft 102 is decelerated to (difference between the number of teeth of the external gear 126 (= 128) and the internal gear 136) / (number of teeth of the external gear 126 (= 128)). . The reduced-speed rotation of the flange body 152 is transmitted to the output shaft 154 formed integrally with the flange body 152, and power is transmitted to a load (not shown) with high efficiency.

<Effects of First Embodiment>
FIG. 7 shows the results of the above operation, with the horizontal axis representing the friction coefficient and the vertical axis representing the efficiency of the intermeshing planetary gear reducer 100 according to the present embodiment. The test example A and B which are this embodiment, the comparative example D and the comparative example E, and the conditions which distribute | arranged the grease which does not contain Mo and S without a coating are shown as the comparative example H. In the figure, the efficiency obtained in Comparative Example H is set to 1, and the efficiency obtained under other conditions is expressed as a relative efficiency with respect to the efficiency of Comparative Example H. As shown in FIG. 7, in the case of Test Example A, the temperature of the intermeshing planetary gear speed reducer 100 decreases twice compared with Comparative Example H, and accordingly, the transmission efficiency is 20% compared with Comparative Example H. It can be confirmed that it is rising.

  That is, the sliding surface subjected to the surface treatment according to this embodiment has a specific surface roughness (Ra 0.07 μm) generated by the roughness processing, and a metal element of W or Cr is added thereon. C-type hard film. Due to this surface roughness, the C-based hard film having a metal element added and excellent in wear resistance and lubricity is formed to be difficult to peel off. Since the surface roughness is processed by shot peening, durability, wear resistance, and impact resistance are high due to improved fatigue strength, and stress corrosion cracking can be prevented. Further, the sliding surface is protected by the C-based hard film, and the wear resistance is also improved. At this time, since the C-based hard film is made by IP (ion plating) that raises the temperature while cleaning the surface on which the film is formed, the adhesion strength to the sliding surface is increased. Furthermore, since a lubricant containing Mo and S as components is disposed between the sliding surfaces facing each other, the Mo and S are easily attracted to the sliding surface by the metal element in the C-based hard film. A Mo-S film having high lubricity can be formed. For this reason, the friction coefficient is reduced at these two sliding surfaces, wear of the sliding surface can be reduced, transmission loss can be greatly reduced, and the heat generated by the friction loss can be reduced. Can be reduced.

  Moreover, since friction loss can be reduced, highly efficient power transmission is possible, and power consumption of a power source that transmits power to the input shaft can be reduced. Further, the internal mesh planetary gear reducer 100, which is a power transmission device, is not subjected to an extra load due to friction loss, and the maintenance cycle can be extended and the product life can be extended.

  In addition, since the surface roughness is set to a specific surface roughness (Ra 0.07 μm) by the roughness processing, even if the two sliding surfaces are worn down to some extent by abrasion, a C-based material to which metal elements (Cr, W) are added Grease, which is a lubricant containing a hard film and Mo and S, exists between the two sliding surfaces. That is, since the Mo-S film having high lubricity remains between the two sliding surfaces for a long period of time, the friction loss is reduced over a long period of time, so that the above-described series of effects can be maintained for a long period of time.

<Matters not limited to the description in the first embodiment>
The application site | part of the sliding part structure of the internal mesh planetary gear speed reducer 100 in the said embodiment is not limited above, For example, the input which opposes the side surface of the external gear 126, and the side surface of the external gear 126 The inner surface of the step cover 144, the side surface of the external gear 126 and the side surface of the spacer 134 facing the side surface of the external gear 126, the side surface of the external gear 128 and the side surface of the spacer 134 facing the side surface of the external gear 128, The present invention may be applied to the inner surface of the output stage cover 146 facing the side surface of the gear 128 and the side surface of the external gear 128. The spacer 134 is a target for surface treatment when the spacer 134 is made of metal.

  Further, the present embodiment is not limited to the above-described intermeshing planetary gear speed reducer, and has a two-stage intermeshing planetary gear speed reduction mechanism or an intermeshing meshed planetary gear speed reducer, The present invention is applicable even when the outer roller and the inner roller are not used.

[Second Embodiment]
Next, a second embodiment according to the present invention will be described with reference to FIG. FIG. 8 is a cross-sectional view of the power transmission device according to this embodiment.

  Note that the surface treatment and the comparative evaluation using the standard sample according to the present embodiment are the same as those in the first embodiment, and thus are omitted.

<Configuration of Second Embodiment>
First, the configuration of a harmonic gear planetary gear reducer that is a power transmission device according to the present embodiment will be described with reference to FIG. The harmonic gear planetary gear speed reducer 200 includes an input shaft 202, a wave generator 208 attached to the input shaft 202, an external gear 210 that is disposed outside the wave generator 208 and elastically deforms, and the external gear. 210 has an internal gear 212 provided with internal teeth that are internally meshed with external teeth provided on the outer periphery of 210. Each component will be described in detail below.

  The input shaft 202 is supported by a bearing 204 and a ball bearing 206 which is a component of the wave generator 208. The bearing 204 is supported on the casing 214 by the input stage cover 216, and the ball bearing 206 is supported by the casing 214 via the external gear 210 and the internal gear 212. The input shaft 202 is a rotating shaft of the wave generator 208, and the wave generator 208 is rotated by the rotation of the input shaft 202.

  The wave generator 208 has a thin ball bearing 206 on the outer periphery of an elliptical cam 207. Although the inner ring of the ball bearing 206 is fixed to the outer periphery of the elliptical cam, the outer ring of the ball bearing 206, that is, the outer peripheral surface 208a of the wave generator 208 is elastically deformed by the rotation of the elliptical cam.

  The external gear 210 is a thin cup-shaped metal elastic body, external teeth are engraved on the outer periphery of the opening, and the center of the cup is attached to the output shaft 220. When the outer circumferential surface 208a of the wave generator 208 is elastically deformed by the rotation of the elliptical cam 207, the outer teeth provided on the outer circumferential surface of the external gear 210 are moved into the inner gear 212. A sliding surface between the outer peripheral surface 208a of the wave generator (first member) 208 and the inner peripheral surface 210a of the external gear (second member) 210, which is the surface facing the outer peripheral surface 208a, in order to internally mesh with the teeth. Is formed. For this reason, the surface treatment which concerns on this embodiment is performed with respect to the two sliding surfaces which the said sliding member opposes. That is, only one of the two opposing sliding surfaces of the pair of sliding members is roughened to an average roughness Ra of about 0.07 μm, and about 2 μm thick with W or Cr added thereon. The grease, which is a lubricant containing Mo and S, is disposed between the pair of sliding surfaces.

  The internal gear 212 is a ring-shaped component, and teeth are carved on the inside. The number of teeth of the external gear 210 is a slight difference (1 to 3), which is larger than that of the external gear 210 and is fixed to the casing 214.

  The output shaft 220 is a rotating shaft of the external gear 210 and is supported by a pair of bearings 222 and 224, and the bearings 222 and 224 are supported by a casing 214.

<Operation of Second Embodiment>
Next, the operation of this embodiment will be described. When power is transmitted from a power source (not shown) via the input shaft 202, the elliptical cam 207 of the wave generator 208 attached and fixed to the input shaft 202 rotates. Then, the outer ring of the wave generator 208 is elastically deformed into an ellipse shape via the ball bearing 206, and the internal gear 212 is in mesh with the internal gear 212 at both ends of the elliptical long axis direction of the external gear 210 generated by the wave generator 208. To do. At this time, the outer peripheral surface 208a of the wave generator 208 and the inner peripheral surface 210a of the external gear 210 opposed to the outer peripheral surface 208a slide on each other, but since the surface treatment described above is applied, there is little wear and transmission. Transmit power with less loss.

  At this time, relative rotation occurs between the external gear 210 and the internal gear 212, and the rotation that is greatly decelerated from the input shaft 202 is extracted to the external gear 210. That is, the rotation of the input shaft 202 is decelerated to (difference between the number of teeth of the external gear 210 and the internal gear 212) / (number of teeth of the external gear 210). The reduced rotation of the external gear 210 is transmitted to an output shaft 220 formed integrally with the external gear 210, and power is transmitted to a load (not shown) with high efficiency.

<Effects of Second Embodiment>
It has the same effect as the first embodiment, and by reducing the friction loss, it is possible to suppress the temperature rise, save power, extend the service life, extend the maintenance cycle, and maintain a series of effects for a long time. Compared to the first embodiment, the harmonic gear planetary gear speed reducer 200 according to the present embodiment has a smaller number of parts, and therefore there may be fewer places where the sliding portion structure is adopted.

<Matters not limited to the description in the second embodiment>
The sliding part structure of the harmonic gear planetary gear speed reducer 200 in the above embodiment is not limited to the above. For example, if the internal teeth of the internal gear 212 and the external teeth of the external gear 210 do not have an involute curve shape but a simple tooth shape, the sliding surface increases at the intermeshing portion. The surface treatment according to the present embodiment may be applied to the moving surface.

  Further, the harmonic gear type planetary gear speed reducer 200 is not limited to the one-stage type of the present embodiment, and may be a two-stage or a combination with another reduction mechanism.

<Matters not limited to the embodiment>
In the above embodiment, the roughness processing is shot peening, but the present invention is not limited to this. That is, the roughness processing can be performed in combination with chemical etching, mechanical cutting, or shot peening.

  Further, the surface roughness of the sliding surface need not be 0.07 μm in average roughness Ra, and preferably 0.03 μm to 0.5 μm in average roughness Ra as described above. When Ra <0.03 μm, the surface is in a mirror state, the adhesion with the carbon-based film cannot be maintained, the carbon-based film is highly likely to disappear when worn by sliding, and the carbon-based film. This is because the effect of reducing the friction coefficient is reduced due to the difficulty of retaining the lubricant after molding. Further, if Ra> 0.5 μm, the surface becomes too rough even after the carbon-based film is molded, and the friction coefficient increases.

  The carbon-based film is not limited to a C-based hard film such as diamond-like carbon (DLC), but may be any film such as graphite that is mainly made of carbon. And not only IP but you may form by physical vapor deposition methods (PVD) and chemical vapor deposition methods (CVD), such as a vapor deposition method. The film thickness of the carbon-based coating at this time is not limited to about 2 μm, and preferably 0.5 μm or more and 10 μm or less. This is because if the film thickness is too thin than 0.5 μm, the film will be worn away in a short time due to friction of the sliding surface, and if it is too thick, it will be easily peeled off by the stress of the film. The metal element added to the carbon-based film is not limited to Cr and W, and the metal element can be any of titanium (Ti), Mo, silicon (Si) which is a metalloid, and the like.

  The amount of the metal element added can be from several atomic weight% to several + atomic weight%. When the carbon-based film is slid under non-lubricated conditions, the carbon-based film exhibits a low coefficient of friction due to its low reactivity on the surface of the Mo-S film, but conversely, in the lubricant, the surface of the film is low. Due to the reactivity, the effect of reducing the friction coefficient is small. Therefore, a Mo-S film is formed on the surface under the above conditions to realize a low friction coefficient in the lubricant. Note that the addition of such a metal element can be easily realized by mixing an appropriate amount of the metal element into carbon, which is the main raw material for vapor deposition, or by vapor deposition simultaneously using another heat source.

  Moreover, Mo and S can each be made into several weight% with respect to the lubricant whole quantity. That is, a commercially available lubricant that is added together with lithium in the form of molybdenum disulfide (MoS2) can also be used. The reason why MoS2 is used is that the molecular structure is a layered lattice structure, and each layer has Mo atoms sandwiched between two S atoms, but the bond between Mo and S is very strong. On the other hand, since the bond between S and S is weak, it easily slips with a low shearing force, so that high lubricity and low friction are exhibited.

  The lubricant is not limited to grease, and lubricating oil or the like can be used.

  Further, the first and second members, which are sliding members, do not need to be limited to the same metal, and may be between different metals, and the roughness processing and the carbon coating on the surface are performed on one side of the sliding surface. Just do it for both.

  The power transmission device is not limited to the inscribed mesh planetary gear speed reducer or the harmonic gear type planetary gear speed reducer, and the present invention includes, for example, a speed reducer composed of a sun gear and a planetary gear, and other speed increasing devices. The present invention can be applied to a general power transmission device including a sliding member including a machine and a sliding portion structure, and a corresponding result can be obtained.

Sectional drawing of the power transmission device which concerns on 1st Embodiment Enlarged view of the sliding part structure enclosed by the broken line in the power transmission device of FIG. Comparison of friction coefficient when sliding surface is realized with standard sample and compared Table showing the results of FIG. Schematic diagram showing the position of the wear surface as an observation surface by an electron beam microanalyzer (EPMA) Display screen showing the result of EPMA analysis of the worn surface shown in FIG. Graph showing friction coefficient, efficiency and temperature measurement results Sectional drawing of the power transmission device which concerns on 2nd Embodiment. Comparison of friction coefficient when comparing conventional sliding surfaces with standard samples Table showing the results of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Internal mesh planetary gear reducer 102, 202 ... Input shaft 104, 106, 156, 158, 204, 222, 224 ... Bearing 110, 112 ... Eccentric body 110a, 112a ... Groove side surface 110b, 112b ... Eccentric body Body groove bottom surface 114, 120 ... Roller bearing 116, 122 ... Roller 116a, 122a ... Roller side surface 118, 124 ... Retainer 126, 128 ... External gear 130, 132 ... Inner pin hole 134 ... Spacer 136 ... Internal gear 136a 136b, 136c, 136d ... inner gear inner surface 138 ... outer roller 138a ... outer roller inner surface 138b ... outer roller side surface 140 ... outer pin 140a ... outer pin outer surface 140b, 140c ... outer pin Both end holding surfaces 142, 214 ... casing 144, 216 ... input stage cover 144a, 14 b, 144c, 144d ... inner surface of input stage cover 146, 218 ... output stage cover 146a, 146b, 146c ... inner surface of output stage cover 148 ... inner pin 148a ... outer peripheral surface of inner pin 150 ... inner roller 150a ... inner roller Peripheral surface 150b ... Side surface of inner roller 152 ... Flange body 152a ... Inner surface 154, 220 ... Output shaft 200 ... Harmonic gear type planetary gear reducer 206 ... Ball bearing 207 ... Elliptical cam 208 ... Wave generator 208a ... Wave generator The outer peripheral surface 210 of the external gear 210a The inner peripheral surface of the external gear 212 The internal gear

Claims (6)

A power transmission device having a sliding portion in which a pair of sliding members slide relative to each other,
At least one of two opposing sliding surfaces of the pair of sliding members is
Surface roughness formed by a predetermined roughness processing;
A metal element is added, and a carbon-based film formed on the surface roughness,
A power transmission device characterized in that a lubricant containing Mo and S as components is disposed between the two facing sliding surfaces. In claim 1,
The power transmission device includes an input shaft, an eccentric body integrated with the input shaft, an external gear that oscillates and rotates by the eccentric body, and an internal tooth that the external gear internally meshes with. An inwardly oscillating mesh planetary gear reducer having a gear and a flange body that is arranged on the outer side in the axial direction of the external gear and connected to an inner pin that extracts a rotation component of the external gear,
Two opposing sliding surfaces of the sliding member are a roller bearing surface disposed between the eccentric body and the external gear, a surface facing the roller side surface, and an outer peripheral surface of the inner pin. And an inner peripheral surface of the inner roller fitted on the inner pin facing the outer peripheral surface of the inner pin, a side surface of the inner roller and a surface facing the side surface of the inner roller, and both ends of the outer pin forming the inner teeth A holding surface and a surface facing the both-end holding surface of the outer pin, an outer peripheral surface of the outer pin, an inner peripheral surface of an outer roller fitted on the outer pin facing the outer peripheral surface of the outer pin, and the outer roller A power transmission device comprising at least one pair of a side surface facing the side surface of the outer roller and the side surface of the outer roller. In claim 1,
The power transmission device includes an input shaft, a wave generator attached to the input shaft, an external gear that is arranged outside the wave generator and elastically deforms, and external teeth provided on the outer periphery of the external gear. A harmonic gear planetary gear reducer having an internal gear with internal teeth meshing internally,
2. The power transmission device according to claim 2, wherein two opposing sliding surfaces of the sliding member are an outer peripheral surface of the wave generator and an inner peripheral surface of the external gear facing the outer peripheral surface of the wave generator. In any one of Claims 1 thru | or 3,
The power transmission device, wherein the surface roughness has an average roughness set between 0.03 μm and 0.5 μm. In any one of Claims 1 thru | or 4,
The carbon-based film has a thickness of 0.5 μm to 10 μm, and the added metal element is at least one of Cr, Ti, Mo, W, and Si. Power transmission device. A sliding part structure of a power transmission device having a sliding part in which the first member and the second member slide with each other,
Between the first member and the second member, a lubricant containing Mo and S as components is disposed,
At least one sliding surface of the first member and the second member is covered with a carbon-based film to which a metal element is added,
And the predetermined roughness process is given to the foundation | substrate of this carbon-type film, The sliding part structure of the power transmission device characterized by the above-mentioned.