Gear system

Abstract

To provide a technology for expanding options of usable greases while extending a service life of a gear device which is incorporated into a food processing machine.SOLUTION: A gear device incorporated in a food processing machine used in a step of processing food comprises: a first gear 60; a second gear 62 that meshes with the first gear 60; grease 76 contained in an internal space where a meshing part of the first gear 60 and the second gear 62 exists; and gap parts 82A to 82C that communicate the internal space to an external space, where the first gear 60 is made of a fiber-reinforced resin. A capacity for the grease 76 is 1% or more and 30% or less of a volume of a grease storage space 90 that is formed by a part of the internal space and stores the grease, and the grease 76 is a grease that does not fall under food grease.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a gear device incorporated in a food machine. [Background Art]

[0002] Patent Document 1 discloses a gear device incorporated in a food machine. This gear device includes food grease accommodated in an internal space where a meshing portion of a gear pair is present, and an oil seal that seals a grease accommodation space for accommodating the food grease. [Prior Art Literature] [Patent Literature]

[0003] [Patent Document 1] Japanese Patent Laid-Open No. 2012-13232 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] The inventor of the present application has found a new idea for expanding the options of usable grease while achieving a longer service life of the gear device in a gear device incorporated in a food machine.

[0005] One object of the present disclosure is to provide a technique for expanding the options of usable grease while achieving a longer service life of the gear device in a gear device incorporated in a food machine. [Means for Solving the Problem]

[0006] A gear apparatus in one aspect of the present disclosure is a gear apparatus incorporated into a food processing machine used in a food handling process, comprising: a first gear; a second gear meshing with the first gear; grease contained in an internal space where the meshing portion of the first gear and the second gear exists; and a gap that allows the internal space to pass to an external space, wherein the first gear is made of fiber-reinforced resin, the amount of grease contained is 1% to 30% of the volume of a grease containment space which is made up of a part of the internal space and contains the grease, and the grease is not food-grade grease. [Effects of the Invention]

[0007] According to this disclosure, in gear systems incorporated into food processing machinery, it will be possible to extend the lifespan of the gear system while expanding the range of greases that can be used. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram showing a food processing machine according to the first embodiment. [Figure 2] This is a side cross-sectional view showing a gear device according to the first embodiment. [Figure 3] This is an explanatory diagram relating to the grease of the first embodiment. [Figure 4] This is a side cross-sectional view showing a gear device according to the second embodiment. [Modes for carrying out the invention]

[0009] The embodiments are described below. The same reference numerals are used for identical components, and redundant explanations are omitted. For the sake of clarity, components are omitted, enlarged, or reduced in each drawing. The drawings should be viewed in accordance with the orientation of the reference numerals.

[0010] First, let me explain the background that led to the invention of the gear apparatus described herein. In the case of a gear apparatus using only metal gears, the amount of grease contained within the gear apparatus varies depending on the type of gear mechanism, but it is generally common technical knowledge that it should be 40% to 50% or more of the volume of the grease containment space (described later). Furthermore, in this case, it is also common technical knowledge that the amount of grease contained will not fall below 25% of the volume of the grease containment space, even if special measures are taken to reduce it (see, for example, Japanese Patent Application Publication No. 2018-144778).

[0011] Furthermore, conventional gear systems are known in which resin gears are constructed from a single material (non-composite material) using resin, and wear between the resin portion of the resin gear and the mating gear is prevented by utilizing the self-lubricating properties of the resin, thereby eliminating the need for grease used to prevent wear between gear pairs. However, such gear systems have insufficient strength in the resin gears and cannot adequately ensure the required lifespan for gear systems incorporated into food processing machinery. Based on this, the inventors of the present invention considered using fiber-reinforced resin, which has excellent strength, as the resin for resin gears in order to ensure the strength of the resin gears. However, it was found that when resin gears made of fiber-reinforced resin are used, if grease is not used, the fibers exposed on the outside of the resin gear cause fiber wear, which wears down the mating gear that meshes with the resin gear, and consequently leads to a shortened lifespan for the gear system.

[0012] The inventors of this application have recognized that, as a countermeasure, it is effective to prevent wear of the mating gear due to fiber abrasion by containing at least a small amount of grease (grease equivalent to 1% or more of the volume of the grease containment space described later). As a result, compared to cases in which resin gears are constructed using a single material made of resin, it is possible to increase the strength of resin gears made of fiber-reinforced resin and prevent the shortened lifespan of gears caused by fiber abrasion by containing at least a small amount of grease, thereby extending the lifespan of the gear system.

[0013] Furthermore, the inventors of this application have newly discovered a configuration that allows for the storage of a significantly smaller amount of grease (less than 30% of the volume of the grease storage space) than the normal range of values ​​(40% to 50% or more) in common technical knowledge, while still accommodating at least a small amount of grease. The inventors of this application have also newly discovered that this configuration allows for the extended lifespan of the gear system while preventing grease leakage. In particular, by significantly reducing the amount of grease to a level lower than the normal range of values ​​in common technical knowledge, it has been newly discovered that grease leakage can be prevented without using a sealing member to enclose grease within the gear system. The reason why the gear system can be extended in lifespan even with such a small amount of grease is, firstly, because one of the gears in the gear pair is made of fiber-reinforced resin, and the self-lubricating properties of the resin can be used to prevent wear at the meshing portion between the resin part (non-fiber part) of the resin gear and the mating gear. Secondly, as mentioned above, by accommodating at least a small amount of grease, fiber wear of the mating gear caused by the fibers of the resin gear can be prevented. In this context, grease leakage refers to the leakage of grease from the grease storage space of a gear mechanism into the outside space.

[0014] Here, it is common technical knowledge that gear systems incorporated into food processing machinery use food-grade grease, as described later, to prevent grease leakage. The inventors of this application have come up with a novel idea that goes against common technical knowledge: by preventing grease leakage by containing at least a small amount of grease, while keeping the grease volume considerably smaller than the normal range of values ​​in common technical knowledge, the lifespan of the gear system can be extended, and grease other than food-grade grease, which is common technical knowledge, can be used in gear systems for food processing machinery. Furthermore, based on this newly obtained idea, the inventors of this application have found a new configuration in which non-food-grade grease (described later) is used instead of food-grade grease as the grease contained in the gear system. As a result, as described later, the range of selectable grease types can be expanded. Since many non-food-grade greases are more advantageous than food-grade grease in improving gear performance (including lifespan), adopting non-food-grade grease makes it possible to improve gear performance, including extending lifespan. The details of the gear system embodiment conceived based on this idea will be described below.

[0015] Refer to Figure 1. Gear units 10-A to 10-E are incorporated into food processing machinery 12 used in food handling processes. Here, "food" refers to anything intended for consumption by living beings such as humans, and includes not only general food (including beverages) but also luxury goods such as tobacco, pharmaceuticals such as oral medications, etc. Here, "food handling processes" refers to processes such as manufacturing, processing, transporting, packaging, filling, and inspection of food. Manufacturing here refers to the act of changing the essence of raw materials into something different. Food processing refers to the act of adding new attributes to food without changing its essence. Food processing includes, for example, cutting, shaping, sorting, crushing, mixing, assorting, portioning, salting, deboning, surface roasting, freezing, thawing, and preventing sticking of food.

[0016] Food processing machinery 12 used in such food handling processes includes, for example, robots 14, washing machines, dewatering machines, slicers, grinders, choppers, mixers, extruders, conveyors, sealers, packaging machines, transport vehicles, etc. Here, a robot 14 used for assembling food products is used as an example of food processing machinery 12. The specific examples of food processing machinery 12 are not limited and may include various types of food processing machinery other than those listed here.

[0017] The robot 14 in this embodiment is a multi-joint robot. The robot 14 in this embodiment has five joints, but the number of joints is not particularly limited and may be four or fewer, six or more, etc. The robot 14 comprises a plurality of joints 16-A to 16-E and a plurality of robot members 18-A to 18-F that are rotatably connected in series by the plurality of joints 16-A to 16-E. Hereinafter, "rotation" includes "rotation" which is rotation in both the forward and reverse directions.Hereinafter, multiple components with the same name will be distinguished by being described sequentially from the tip side to the base side of the robot 14, for example, as "first stage gear unit 10-A", "second stage gear unit 10-B", etc. The same applies to other components (joints 16-A, etc.).

[0018] Each of the plurality of joints 16-A to 16-E incorporates a driving device (not shown) that drives to rotate the distal-end-side robot members 18-A to 18-E among the two robot members 18-A to 18-F connected at the joints 16-A to 16-E. The gear devices 10-A to 10-E are incorporated as part of the respective driving devices of the plurality of joints 16-A to 16-E, and are used for transmitting power of the driving devices.

[0019] Among the plurality of robot members 18-A to 18-F, the most proximal-end-side robot member 18-F serves as a base that supports other members of the robot 14, and the other robot members 18-A to 18-E serve as arm members. In the present embodiment, among adjacent robot members 18-A to 18-F, the distal-end-side robot members 18-A to 18-E are rotatably connected to the proximal-end-side robot members 18-B to 18-F at the joints 16-A to 16-E.

[0020] Among the plurality of robot members 18-A to 18-F, the most distal-end-side robot member 18-A is provided with a mounting portion 22 that detachably mounts an attachment 20. The attachment 20 is, for example, a gripping member (gripper) that grips an article such as food. Specific examples of the attachment 20 are not particularly limited, and the attachment may be a suction member that sucks an article by negative pressure, magnetic force, or the like, a scooping member that scoops an article, or the like.

[0021] Reference is made to FIG. 2. Components common to a plurality of gear devices 10-A to 10-E will be described below. When these common components are collectively referred to without being distinguished, terms for distinguishing them (such as "first" at the beginning and "-A" at the end) will be omitted. For example, when collectively referring to each of the gear devices 10-A to 10-E such as the first-stage gear device 10-A and the second-stage gear device 10-B, they are simply described as gear device 10. Additionally, hereinafter, the direction along the rotation center line C52 of the output member 52 (described later) of the gear device 10 is simply referred to as the axial direction, and the radial direction centered on the rotation center line C52 and the circumferential direction are also simply referred to as the radial direction and the circumferential direction. Further, among the axial directions, the drive source 30 side is referred to as the input side, and the opposite side is referred to as the anti-input side. In the present embodiment, an example in which all of the plurality of gear devices 10-A to 10-E include the same gear mechanism will be described. The size and reduction ratio of the gear mechanism in each gear device 10-A to 10-E differ according to the required torque and required strength of each joint. The plurality of gear devices 10-A to 10-E may have different gear mechanisms. Further, it is not necessary to adopt the gear device of the present disclosure for all of the gear devices 10-A to 10-E, and it is sufficient to adopt the gear device of the present disclosure for at least some of the gear devices. In this case, it is preferable to adopt the gear device of the present disclosure for the gear device 10-A closer to the drive source.

[0022] The gear device 10 of the present embodiment uses a cylindrical strain-wave gear mechanism. This strain-wave gear device 10 includes: a wave generator shaft 32 to which rotation is input from a drive source 30; an external gear 34 flexurally deformed by the wave generator shaft 32; and a speed change internal gear 36A and an output internal gear 36B that mesh with the external gear 34. In addition, the gear device 10 includes a casing 38, an input-side cover 40A, and an anti-input-side cover 40B. The drive source 30 of the present embodiment is a motor, but a gear motor, an engine, or the like may also be used.

[0023] The vibrator shaft 32 comprises a vibrator 32a that causes the external gear 34 to bend and deform, and shaft portions 32b provided on both sides of the vibrator 32a in the axial direction. The vibrator shaft 32 is an example of an input shaft to which rotation is input from the drive source 30. A hollow portion 32c is formed in the center of the vibrator shaft 32, penetrating in the axial direction. In a cross-section perpendicular to the axial direction of the vibrator 32a, the outer shape of the vibrator 32a is elliptical, and the outer shape of the shaft portion 32b is circular. Here, "elliptical" is not limited to a geometrically strict ellipse, but also includes an approximate ellipse.

[0024] The external gear 34 is a flexible cylindrical member. External teeth are provided on the outer circumference of the external gear 34. Restricting members 42 are arranged on both sides of the external gear 34 in the axial direction to restrict the axial movement of the external gear 34.

[0025] The inner circumference of the internal gear 36A for speed shifting is provided with internal teeth that mesh with the external teeth on the input side of the external gear 34. The inner circumference of the internal gear 36B for output is provided with internal teeth that mesh with the external teeth on the non-input side of the external gear 34. The internal gear 36A for speed shifting has a different number of internal teeth (e.g., 102) than the number of external teeth (e.g., 100) of the external gear 34, while the internal gear 36B for output has the same number of internal teeth as the number of external teeth of the external gear 34.

[0026] The casing 38 of this embodiment comprises an input-side casing member 38a and an anti-input-side casing member 38b. The input-side casing member 38a and the anti-input-side casing member 38b are connected by a connecting member B1 such as a bolt. The input-side casing member 38a also serves as a gear-shifting internal gear 36A. The anti-input-side casing member 38b is positioned radially outward of the output internal gear 36B.

[0027] The input-side cover 40A is positioned on the axial input side relative to the external gear 34 and covers the external gear 34 from the input side. The input-side cover 40A is connected to the variable-speed internal gear 36A by connecting members B2 such as bolts. The non-input-side cover 40B is positioned on the axial non-input side relative to the external gear 34 and covers the external gear 34 from the non-input side. The non-input-side cover 40B is connected to the output internal gear 36B by connecting members B3 such as bolts.

[0028] The gear unit 10 includes an output member 52 that outputs rotation to an external driven member 50, and a fixing member 56 that is fixed to an external fixed member 54. In this embodiment, the driven member 50 and the fixed member 54 are the robot members 18 described above. The output member 52 drives the driven member 50 by outputting rotation to the driven member 50. The output member 52 is one of the casing 38 and the non-input side cover 40B, and the fixing member 56 is the other of the casing 38 and the non-input side cover 40B. In this embodiment, the non-input side cover 40B is the output member 52 and the casing 38 is the fixing member 56, but the reverse may also be true. The output member 52 is connected to the driven member 50 using connecting members (not shown) such as bolts and rivets. The fixing member 56 is connected to the fixed member 54 using connecting members B4 such as bolts and rivets.

[0029] The operation of the gear device 10 described above will now be explained. When the vibrator 32a of the vibrator shaft 32 rotates, the external gear 34 is deflected and deformed to form an elliptical shape that matches the shape of the vibrator 32a. When the external gear 34 is deflected and deformed in this way, the meshing position of the external gear 34 and the internal gears 36A and 36B changes in the direction of rotation of the vibrator 32a. At this time, with each rotation of the external gear 34 and the speed-shifting internal gear 36A, which have different numbers of teeth, the meshing teeth of these gears shift in the circumferential direction. As a result, one of them (the external gear 34 in this embodiment) rotates, and its rotational component is extracted as output rotation by the output member 52. In this embodiment, the external gear 34 and the output internal gear 36B have the same number of teeth and are therefore synchronized, and the rotational component of the external gear 34 is extracted by the non-input side cover 40B, which is the output member 52, through the output internal gear 36B, which is synchronized with the external gear 34. At this time, the output rotation, which is decelerated (in this case reduced) in response to the input rotation input to the vibrator shaft 32, is extracted by the output member 52 at a speed ratio corresponding to the difference in the number of teeth between the external gear 34 and the internal gear 36A for speed change.

[0030] Refer to Figure 3. In Figure 3, hatching of the cross-section of the members is omitted for the sake of explanation. The gear device 10 described above comprises a first gear 60 and a second gear 62 that meshes with the first gear 60. In this embodiment, the first gear 60 is an internal gear 36A for speed change and an internal gear 36B for output, respectively, and the second gear 62 is an external gear 34.

[0031] The gear unit 10 is equipped with at least one bearing 70A to 70D. The bearings 70A to 70D in this embodiment include a vibrator bearing 70A disposed between the vibrator 32a of the vibrator shaft 32 and the external gear 34, and a main bearing 70B disposed between the casing 38 and the output internal gear 36B. In addition to these, the bearings 70A to 70D also include an input-side input bearing 70C disposed between the input-side cover 40A and the shaft portion 32b of the vibrator shaft 32, and a non-input-side input bearing 70D disposed between the non-input-side cover 40B and the shaft portion 32b of the vibrator shaft 32. The main bearing 70B is shown as a ball bearing, but its specific example is not particularly limited, and may be a roller bearing, cross roller bearing, angular contact ball bearing, tapered bearing, etc. The input bearings 70C and 70D are shown as ball bearings, but their specific examples are not particularly limited, and may be a roller bearing, angular contact ball bearing, tapered bearing, etc.

[0032] Each bearing 70A to 70D comprises an outer ring 70a and an inner ring 70b, and rolling elements 70c that roll on the outer ring 70a and the inner ring 70b. The outer ring 70a and the inner ring 70b are provided with rolling surfaces 70d on which the rolling elements 70c roll. For the sake of explanation, only the rolling surface 70d of the main bearing 70B is given a reference numeral here. Each of the bearings 70A to 70D may have a dedicated outer ring 70a, or an outer member positioned on the outer circumference of the rolling elements 70c may also serve as the outer ring 70a. Here, we show an example where all bearings 70A to 70D have a dedicated outer ring 70a. Similarly, each of the bearings 70A to 70D may have a dedicated inner ring 70b, or an inner member positioned on the inner circumference of the rolling elements 70c may also serve as the inner ring 70b. Here, we show an example in which bearings 70B to 70D other than the vibrator bearing 70A are equipped with a dedicated inner ring 70b, and the inner ring 70b of the vibrator bearing 70A is also provided by an inner member (in this case, the vibrator 32a). The vibrator bearing 70A in this embodiment is a double-row bearing equipped with two outer rings 70a and rolling elements 70c. The vibrator bearing 70A is equipped with a retainer 70e that holds the positions of the multiple rolling elements 70c.

[0033] The gear unit 10 includes a plurality of relative rotating bodies 72A to 72C that rotate relative to each other during its operation. In this embodiment, the plurality of relative rotating bodies 72A to 72C consist of a first relative rotating body 72A including a casing 38, a second relative rotating body 72B including an anti-input side cover 40B, and a third relative rotating body 72C including a vibrator shaft 32. The first relative rotating body 72A includes, in addition to the casing 38, the outer ring 70a of the main bearing 70B, the internal gear for speed change 36A, the input side cover 40A, and the outer ring 70a of the input side input bearing 70C. The second relative rotating body 72B includes, in addition to the anti-input side cover 40B, the internal gear for speed change 36A, the inner ring 70b of the main bearing 70B, and the outer ring 70a of the anti-input side input bearing 70D. The third relative rotating body 72C includes, in addition to the vibrator 32a, the inner ring 70b of the non-input side input bearing 70D and the inner ring 70b of the input side input bearing 70C. The components of each relative rotating body 72A to 72C are integrated.

[0034] The gear unit 10 is equipped with grease 76 contained in its internal space 74. The grease 76 is contained in the internal space 74 of the gear unit 10 where the meshing portion 78 of the first gear 60 and the second gear 62 is located. In addition to the meshing portion 78 of the gears 60 and 62, this internal space 74 also contains the rolling points (rolling elements 70c and rolling surfaces 70d) of the bearings 70A to 70D of the gear unit 10. The grease 76 is applied to the tooth surfaces of the first gear 60 and the second gear 62, as well as to the rolling points (rolling elements 70c and rolling surfaces 70d) of the bearings 70A to 70D. In Figure 3, the tooth surfaces of the gears 60 and 62 and the rolling elements 70c, which are the main application points of the grease 76, are hatched.

[0035] The gear unit 10 is provided with at least one gap 82A to 82C that allows the internal space 74 to pass through to the external space 80 located outside the gear unit 10. The gaps 82A to 82C are provided at the location in the internal space 74 of the gear unit 10 that is closest to the external space 80. Regardless of whether there is an actual sealing member in the gaps 82A to 82C, the gaps 82A to 82C allow the internal space 74 to communicate with the external space 80, assuming that the gaps 82A to 82C are not sealed by a sealing member. In this embodiment, as will be described later, no sealing member is provided in the gaps 82A to 82C.

[0036] The gaps 82A to 82C are formed between a pair of relative rotating bodies 72A to 72C that rotate relative to each other. The gaps 82A to 82C in this embodiment include a low-speed gap 82A formed between a pair of relative rotating bodies 72A and 72B that rotate relative to each other at a first relative rotational speed, and high-speed gaps 82B and 82C formed between a pair of relative rotating bodies 72A to 72C that rotate relative to each other at a second relative rotational speed faster than the first relative rotational speed. The low-speed gap 82A in this embodiment is formed between the first relative rotating body 72A and the second relative rotating body 72B. The high-speed gaps 82B and 82C in this embodiment include a first high-speed gap 82B formed between the second relative rotating body 72B and the third relative rotating body 72C, and a second high-speed gap 82C formed between the first relative rotating body 72A and the third relative rotating body 72C. There is a slight difference between the second relative rotation speeds of the second relative rotating body 72B and the third relative rotating body 72C, and the second relative rotation speeds of the first relative rotating body 72A and the third relative rotating body 72C. However, these second relative rotation speeds are significantly faster than the first relative rotation speeds of the first relative rotating body 72A and the second relative rotating body 72B.

[0037] Spaces formed radially inward of a single relative rotating body 72A to 72C, and not located axially sandwiched between other relative rotating bodies 72A to 72C, do not fall under the category of gaps 82A to 82C that become part of the internal space 74, and are treated as part of the external space 80. Spaces that satisfy this condition include, for example, the space formed within the hollow portion 32c of the vibrator 32a constituting the third relative rotating body 72C, as well as the space 84 provided radially inward of the first high-speed gap 82B in the anti-input side cover 40B constituting the second relative rotating body 72B.

[0038] In this embodiment, a main bearing 70B (low-speed bearing) is provided in the low-speed gap 82A (on the internal space side) to allow relative rotation while maintaining the distance between the first relative rotating body 72A and the second relative rotating body 72B. In addition, an input bearing 70D (first high-speed bearing) is provided in the first high-speed gap 82B (on the internal space side) to allow relative rotation while maintaining the distance between the second relative rotating body 72B and the third relative rotating body 72C. In addition, an input bearing 70C (second high-speed bearing) is provided in the second high-speed gap 82C (on the internal space side) to allow relative rotation while maintaining the distance between the first relative rotating body 72A and the third relative rotating body 72C. In other words, the gaps 82A to 82C are provided with bearings 70B to 70D that allow relative rotation while maintaining the distance between the pair of relative rotating bodies 72A to 72C that form the gaps 82A to 82C.

[0039] The casing 38 (part of the first relative rotating body 72A) is provided with a first projection 86A that protrudes radially inward and forms the low-speed side gap 82A. The non-input side cover 40B (part of the second relative rotating body 72B) is provided with a second projection 86B that protrudes radially outward and forms the low-speed side gap 82A. The non-input side cover 40B (part of the second relative rotating body 72B) is provided with a third projection 86C that protrudes radially inward and forms the first high-speed side gap 82B. The input side cover 40A (part of the first relative rotating body 72A) is provided with a fourth projection 86D that protrudes radially inward and forms the second high-speed side gap 82C.

[0040] In the gaps 82A to 82C, a minimum gap portion 88 is provided where either the axial dimension or the radial dimension is smallest within the gaps 82A to 82C. Here, the minimum gap portion 88 is double-hatched. The minimum gap portion 88 of the low-speed side gap portion 82A is provided axially sandwiched between the first protrusion 86A of the casing 38 and the second protrusion 86B of the non-input side cover 40B, where the axial dimension is smallest in the low-speed side gap portion 82A. The minimum gap portion 88 of the first high-speed side gap portion 82B is provided axially sandwiched between the third protrusion 86C of the non-input side cover 40B and the inner ring 70b of the non-input side input bearing 70D, where the axial dimension is smallest in the first high-speed side gap portion 82B. The smallest gap portion 88 of the second high-speed side gap portion 82C is provided radially sandwiched between the fourth protrusion 86D of the input side cover 40A, which has the smallest radial dimension in the second high-speed side gap portion 82C, and the shaft portion 32b of the vibrator shaft 32. The smallest gap portion 88 of each of the gap portions 82A to 82C is provided on the external space 80 side of the bearings 70B to 70D that maintain the distance between the pair of relative rotating bodies 72A to 72C that form the gap portion 82A to 82C. For example, the smallest gap portion 88 of the low-speed side gap portion 82A is provided on the external space 80 side of the main bearing 70B that maintains the distance between the first relative rotating body 72A and the second relative rotating body 72B that form the smallest gap portion 88.

[0041] The first gear 60 is a resin gear made of fiber-reinforced resin. This makes it possible to reduce the weight and increase the strength of the first gear 60. This fiber-reinforced resin is made by incorporating reinforcing fibers into a base resin. The base resin may be various general-purpose engineering plastics such as polyamide (PA), polycarbonate (PC), and polyacetal (POM). In addition, the base resin may be various special engineering plastics such as polyetheretherketone (PEEK), polyamideimide (PAI), and polyphenylene sulfide (PPS). The reinforcing fibers may be various reinforcing fibers such as carbon fiber, glass fiber, aramid fiber, polyethylene fiber, Zylon fiber, and boron fiber.

[0042] The second gear 62 is made of a metallic material. Here, a metallic material refers to a material whose main component is metal. This metallic material may be made only of the main component metal (including alloys), or it may be made of a composite material (such as fiber-reinforced metal) of the main component metal and other components. The metals used here include, for example, iron-based materials such as cast iron and steel, and aluminum-based materials such as aluminum and aluminum alloys. By making the second gear 62 out of a metallic material in this way, the strength of the second gear 62 can be increased compared to when the second gear 62 is made out of a resin-based material, and a longer lifespan for the gear device 10 can be expected. In addition, the heat generated at the meshing part can be dissipated through the metal gear, which has high thermal conductivity, and wear of the resin gear and grease can be suppressed.

[0043] The bearings 70A to 70D of the gear unit 10 are made of metallic materials. For example, the bearings 70A to 70D are made of steel materials such as high-carbon chromium bearing steel. To achieve this, the outer ring 70a, inner ring 70b, rolling elements 70c, and retainer 70e of the bearings 70A to 70D are each made of metallic materials.

[0044] Furthermore, the exciter 32a, regulating member 42, connecting members B1 to B3, etc. of the gear unit 10 are made of metallic materials. In addition, the casing 38, non-input side cover 40B, input side cover 40A, etc. of the gear unit 10 are made of resin-based materials. Resin-based materials here refer to materials whose main component is resin. These resin-based materials may be made only of the main component resin, or they may be made of composite materials of the main component base resin and other components. Composite materials here refer to, for example, cloth bakelite, paper bakelite, etc., in addition to the fiber-reinforced resin mentioned above.

[0045] As described above, the gear device 10 of this embodiment is characterized in that at least the first gear 60 of the gear pair consisting of the first gear 60 and the second gear 62 is a resin gear made of fiber-reinforced resin, and that it accommodates at least a small amount of grease 76 while having a grease capacity that is considerably less than that of common technical knowledge. In order to achieve this, in this embodiment, the volume [ml] of the grease 76 to be accommodated is set to be 1% or more and 30% or less of the volume [ml] of the grease storage space 90 which is formed by a part of the internal space 74 and accommodates the grease 76.

[0046] Here, "grease containment space 90" refers to a portion of the internal space 74 that lies inside the sealed portion when the predetermined portion of the gap 82A to 82C that allows the internal space 74 to pass through to the external space 80 is sealed. Here, "a portion of the internal space 74" refers to the portion in which grease 76 can reside, and is the space of the internal space 74 that lies inside the sealed portion, excluding the occupied areas of components present in the internal space 74, such as the gears 60, 62 and bearings 70A to 70D. Here, the grease containment space 90 is indicated by hatching. Here, "predetermined portion" refers to the location where a sealing member such as an oil seal or a sealing bearing is provided in the gap 82A to 82C, and the area inside the internal space 74 beyond that sealing member becomes the grease containment space 90. In contrast, the "designated location" refers to the smallest gap portion 88 of the gap portions 82A to 82C when a sealing member is not provided in the gap portions 82A to 82C, and the area inside the internal space 74 beyond that smallest gap portion 88 becomes the grease storage space 90. The volume of this grease storage space 90 may be determined by the volume of liquid that can be sealed in the internal space 74 inside the sealed portion when the designated location of the gap portions 82A to 82C is sealed.

[0047] The upper limit (30%) of the grease 76 capacity is significantly lower than the normal range of common technical knowledge (40-50% or more), and is intended to define a desirable range as a guideline. This upper limit itself does not have any particular technical significance (critical significance). As will be described later, by setting the grease 76 capacity to 30% or less of the volume of the grease storage space 90, grease leakage from the gear unit 10 can be prevented compared to the normal range of common technical knowledge (40-50% or more), thereby allowing the use of grease 76 other than food-grade grease. In particular, grease leakage can be prevented without using a sealing member to enclose the grease 76 within the gear unit 10.

[0048] The lower limit of the grease 76 capacity (1%) represents the presence of at least a small amount of grease compared to the case where no grease 76 is used at all, and defines a desirable numerical range as a guideline. This lower limit does not have any particular technical significance (critical significance). As will be described later, by setting the amount of grease 76 to 1% or more of the volume of the grease storage space 90, it becomes possible to expect a longer lifespan for the gear mechanism by preventing fiber wear compared to the case where no grease 76 is used at all.

[0049] The amount of grease 76 to be contained is preferably 3% to 20% of the volume of the grease containment space 90, more preferably 3% to 15%, and even more preferably 4% to 10%.

[0050] Grease 76 is a grease that does not fall under the category of food-grade grease (hereinafter referred to as "non-food-grade grease"). Food-grade grease, as used here, refers to a lubricant that has been certified by a public institution as usable in areas that come into contact with food, according to the standards for food-grade machinery lubricants. These standards for food-grade machinery lubricants include, for example, the NSF (National Sanitation Foundation) standards NSF H1 and NSF 3H, but other standards that require similar criteria may also be used. In the case of NSF H1 and NSF 3H, food-grade grease can also be said to be registered with the NSF as a lubricant that meets the standards required by these standards.

[0051] Food-grade greases contain baby oil, white oil, etc., as base oils and do not contain mineral oils. In contrast, general-purpose greases other than food-grade greases usually contain such mineral oils as base oils. Non-food-grade greases can be considered to contain such mineral oils as base oils. Non-food-grade greases may also contain one of the components commonly used in general-purpose greases as an additive: lead, ammonia, cadmium, or nickel.

[0052] When a sealing member is not used, it is preferable that grease 76 has a certain degree of hardness in order to reliably prevent grease leakage. From this viewpoint, it is preferable to use a consistency number of 1 to 6 for grease 76, and more preferably 1 to 2. The consistency number here refers to the number used to classify grease according to the range of mixed consistency as specified in JIS K2220. When a sealing member is used, a consistency number of 000 to 0 for grease 76 may be used.

[0053] In the gear unit 10, there are two places where grease 76 should be applied to prevent wear between components: the meshing portion 78 of the gear pair and the rolling portion (rolling element 70c and rolling surface 70d) of the bearings 70A to 70D. Of these, the rolling portion of the bearings 70A to 70D requires significantly less grease to ensure their lifespan compared to the meshing portion 78 of the gear pair. Therefore, if the number of bearings 70A to 70D used in the gear unit 10 is within the range of the number normally used (for example, 2 or more to 6 or less), then containing at least a small amount of grease (1% or more of the volume of the grease containment space 90) is sufficient to ensure the lifespan of the gear unit 10.

[0054] The surface roughness R1 of the rolling elements 70c and rolling surfaces 70d of bearings 70A to 70D is smaller than the surface roughness R2 of the tooth surfaces constituting the meshing portions 78 of the first gear 60 and the second gear 62. In this embodiment, this condition is satisfied in all bearings 70A to 70D, but it may be satisfied in at least one of the bearings 70A to 70D. This reduces the amount of grease required to ensure the required lifespan of bearings 70A to 70D compared to the case where the surface roughness R1 of bearings 70A to 70D is larger than the surface roughness R2 of each gear 60, 62. The amount of grease required to ensure the lifespan of bearings 70A to 70D is already small, but it can be reduced even further. Consequently, a reduction in the amount of grease to be contained in the gear unit 10 can be expected.

[0055] In this embodiment, the gaps 82A to 82C of the gear unit 10 are not sealed by a sealing member. Here, the sealing member refers to a member that prevents grease 76 from flowing out of the grease containment space 90 to the external space 80. In this embodiment, this condition is satisfied in each of the multiple gaps 82A to 82C. That is, it is satisfied in each of the low-speed side gap 82A, the first high-speed side gap 82B, and the second high-speed side gap 82C. By omitting the sealing member in the gaps 82A to 82C of the gear unit 10 in this way, the cost of the gear unit 10 can be reduced, and losses due to the sliding of the sealing member can be reduced. Furthermore, by omitting the sealing member in each of the low-speed side gap 82A and the high-speed side gaps 82B and 82C, the cost of the gear unit 10 can be further reduced and losses can be reduced.

[0056] The effects of the gear device 10 described above will now be explained. According to the gear device 10 of this embodiment, by storing at least a small amount of grease while keeping the amount of grease to a level considerably smaller than the normal numerical range of common technical knowledge, grease leakage can be prevented, making it possible to use non-food grease instead of food grease. As a result, the lifespan of the gear device can be extended compared to when resin gears are constructed using a single material made of resin, and as will be explained next, the range of types of grease 76 that can be used can be greatly expanded compared to when food grease is used.

[0057] Food-grade greases have significantly more limited options for the types of components (base oil, additives, etc.) that can be used compared to non-food-grade greases, and tend to have inferior characteristics in terms of operating temperature range and lifespan. In this respect, by using non-food-grade grease instead of food-grade grease, the range of components that can be used in grease 76 can be greatly expanded. In other words, the range of usable grease 76 types can be greatly expanded. Furthermore, by selecting grease 76 with appropriate components according to the desired characteristics, it is possible to easily improve performance in those characteristics, and thus improve the performance and lifespan of the gear unit 10. In addition, food-grade greases are usually much more expensive than non-food-grade greases. By using non-food-grade grease instead of food-grade grease, the range of usable grease 76 can be expanded, and by selecting inexpensive non-food-grade grease, it is possible to easily reduce costs.

[0058] Next, we will describe the tests conducted to confirm the effectiveness of the gear device 10 of this embodiment. The gear device 10 of this embodiment has a novel feature in its idea, which goes against common technical standards, as it allows the use of grease 76 other than food-grade grease while ensuring the lifespan of the gear device 10, by accommodating at least a small amount of grease (1% or more) while significantly reducing the actual amount of grease contained (30% or less) compared to common technical standards. For this reason, as mentioned above, although there is no critical significance in the numerical range of 1% to 30% of the volume of the grease containment space 90, we conducted tests to confirm its effectiveness. In these tests, using the gear device 10 shown in Figure 2, the amount of grease 76 contained was set to 5.4% of the volume of the grease containment space 90. In addition, in these tests, a load in the forward rotation direction and a load in the reverse rotation direction were repeatedly applied to the output member 52. This load was set to the average size of a load applied to a gear device 10 incorporated into a food processing machine 12. As a result, it was confirmed that the required lifespan for the gear unit 10 incorporated into the food processing machine 12 was met, and that grease leakage did not occur even without a sealing member.

[0059] Furthermore, based on these test results, simulations were conducted under various conditions with different loads and operating conditions. These operating conditions include the position (number of stages) of the joints 16-A to 16-E of the articulated robot in which the gear unit 10 is used, and the posture of the gear unit 10 in the articulated robot 14. The results showed that even with a grease volume of 1% of the grease storage space, there are situations where the required lifespan for the gear unit 10 incorporated into the food processing machine 12 is satisfied. It was also found that even with a grease volume of 30% of the grease storage space, there are situations where grease leakage from the gear unit 10 does not occur. Moreover, to enable greater versatility and adaptability to various applications, it was found that the grease volume 76 is preferably 3% to 20% of the grease storage space 90, more preferably 3% to 15%, and even more preferably 4% to 10%.

[0060] (Second Embodiment) Refer to Figure 4. Hereinafter, among the components described in the first embodiment, components not described below will be treated the same as in the first embodiment. The gear device 10 of this embodiment differs from the gear device 10 of the first embodiment in the configuration of the main bearing 70B and input bearings 70C and 70D. The main bearing 70B provided in the low-speed side gap 82A is a sealed bearing. Similarly, the input bearings 70C and 70D provided in the high-speed side gaps 82B and 82C are also sealed bearings. Here, we will explain the configuration common to both, using the main bearing 70B as an example.

[0061] The seal bearing constituting the main bearing 70B includes an outer ring 70a, an inner ring 70b, rolling elements 70c, and a seal material 70f positioned between the outer ring 70a and the inner ring 70b. The seal material 70f is intended to prevent grease from flowing out of the grease containment space 90 to the external space 80. By arranging the seal bearing in the gaps 82A to 82C in this way, leakage of grease contained in the grease containment space 90 can be prevented more reliably. From this viewpoint, as in this embodiment, a seal bearing may be placed in each of the multiple gaps 82A to 82C, or a seal bearing may be placed in at least one of the multiple gaps 82A to 82C.

[0062] Thus, the gaps 82A to 82C of the gear unit 10 may be sealed by a sealing member. The specific example of this sealing member is not particularly limited, but for example, in addition to a sealing bearing, it may be composed of an oil seal or the like. Furthermore, if a portion of the multiple gaps 82A to 82C is sealed by a sealing member, only one of the low-speed gap 82A and the high-speed gaps 82B and 82C may be sealed by the sealing member. In addition, one of the multiple high-speed gaps 82B and 82C and the low-speed gap 82A may be sealed by separate sealing members.

[0063] In this embodiment, the grease storage space 90 is located inside the internal space 74, in accordance with the definition described above, and is provided in the gaps 82A to 82C, where the seal bearings serve as sealing members.

[0064] Next, we will describe the transformation forms of each component described so far.

[0065] The specific type of gear mechanism used in the gear unit 10 is not particularly limited. In addition to a flexible meshing gear mechanism, the gear mechanism may also be a simple planetary gear mechanism, an eccentric oscillating gear mechanism, a parallel shaft gear mechanism, an orthogonal shaft gear mechanism, etc. In the case of a flexible meshing gear mechanism, the specific type is not particularly limited, and it may be cylindrical, cup-shaped, or top-hat-shaped. The flexible gear that deforms by bending due to the vibrating body may be an internal gear instead of an external gear. In the case of an eccentric oscillating gear mechanism, the specific type is not particularly limited. In addition to the center-crank type in which the crankshaft is positioned at the rotation center of the output member, this type may also be a distribution type in which the crankshaft is positioned at an offset position from the rotation center of the output member.

[0066] The specific combination of the first gear 60 and the second gear 62 is not particularly limited. Although an example has been described in which the first gear 60, which is a resin gear, is an internal gear and the second gear 62 is an external gear, the first gear 60 may be an external gear and the second gear 62 may be an internal gear. In addition, the combination of the first gear 60 and the second gear 62 may be a pair of bevel gears, a rack and pinion, a screw gear and a helical gear, etc.

[0067] The materials of the components of the gear unit 10 are not particularly limited; the first gear 60 may be made of fiber-reinforced resin, but the materials of the other components are not limited. The second gear 62 may be made of a resin-based material such as fiber-reinforced resin instead of a metallic material. Other components of the gear unit 10 (for example, the main bearing 70B, the vibrator 32a, etc.) may also be made of either metallic or resin-based materials.

[0068] The surface roughness R1 of the rolling elements 70c and rolling surfaces 70d of bearings 70A to 70D may be greater than or equal to the surface roughness R2 of the tooth surfaces of the first gear 60 and the second gear 62.

[0069] The embodiments and variations described above are illustrative. The abstract technical ideas derived from them should not be interpreted restrictively to the content of the embodiments and variations. Many design changes are possible, such as changing, adding, or deleting components, in the embodiments and variations. In the embodiments described above, the content that allows for such design changes is emphasized with the notation "embodiment." However, design changes are also permitted in content without such notation. [Explanation of Symbols]

[0070] 10...Gear unit, 12...Food processing machinery, 60...First gear, 62...Second gear, 70A~70D...Bearing, 70c...Rolling element, 70d...Rolling surface, 72A~72C...Relative rotating body, 74...Internal space, 76...Grease, 78...Meshing part, 80...External space, 82A...Low-speed side clearance, 82B, 82C...High-speed side clearance, 90...Grease storage space.

Claims

1. A gear mechanism incorporated into food processing machinery used in food handling processes, The first gear and, A second gear that meshes with the first gear, Grease contained in the internal space where the meshing portion of the first gear and the second gear exists, It comprises a gap that allows the internal space to pass through to the external space, The first gear is made of fiber-reinforced resin, The amount of grease to be contained is 1% to 30% of the volume of the grease containment space which is formed by a part of the internal space and contains the grease. The aforementioned grease is a grease that does not fall under the category of food-grade grease. The gear apparatus is such that the gap is not sealed by a sealing member, or is sealed by a sealing bearing that separates the internal space containing the grease from the external space.

2. The aforementioned gap is not sealed by a sealing member. The gear apparatus according to claim 1, wherein the internal space containing the grease is in communication with the external space.

3. The gear apparatus according to claim 2, wherein the gap portion includes a low-speed side gap portion formed between a pair of relative rotating bodies rotating at a first relative rotational speed, and a high-speed side gap portion formed between a pair of relative rotating bodies rotating at a second relative rotational speed faster than the first relative rotational speed.

4. The gear apparatus according to claim 1, wherein the amount of grease contained is 3% or more and 20% or less of the volume of the grease containment space.

5. The gear apparatus according to claim 1, wherein the second gear is made of a metallic material.

6. Equipped with bearings made of metallic materials, The gear apparatus according to claim 1, wherein the surface roughness of the rolling elements and rolling surfaces of the bearing is smaller than the surface roughness of the tooth surfaces of the first gear and the second gear.

7. The gear apparatus according to claim 1, wherein all grease in the grease containment space is grease that does not fall under the category of food grease.

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