deceleration device

Abstract

The objective of this invention is to provide a technology that enables the lightweighting of a speed reduction device. The speed reduction device (10) of this invention comprises: a housing (40) on which an internal gear (34) is provided; an external gear (32) meshing with the internal gear; and a wheel carrier (36) disposed on the axial side of the external gear and rotatably supported on the housing. The speed reduction device has a hollow portion (24) extending through the axial direction (X) at its radial center. The speed reduction device comprises: a central tube (42) disposed through the external gear and the wheel carrier and forming the hollow portion; and a protective member (44) disposed adjacent to the end of the central tube in the axial direction and forming the end of the hollow portion. The protective member is fixed to the wheel carrier and is configured such that the circumscribed circle of the maximum diameter (Ra) centered on the central axis (La) of the internal gear and circumscribed outside the wheel carrier falls radially inside the protective member.

Description

[0001] This application is a divisional application of Chinese Patent Application No. 201810762997.2, filed on July 12, 2018, entitled "Deceleration Device". This application claims priority based on Japanese Patent Application No. 2017-206099, filed on October 25, 2017. The entire contents of that Japanese application are incorporated herein by reference. Technical Field

[0002] This invention relates to a speed reduction device. Background Technology

[0003] Industrial machinery such as robotic arms or machine tools are machines that perform rotary movements by reciprocating within a specified angular range. These machines typically have a base component and a rotating component that rotate relative to each other during the rotary motion. Sometimes, such industrial machinery is equipped with a reduction gear with a hollow portion through which a cable or other insertion component is inserted. The base-side portion of this insertion component is sometimes fixed to the base component of the industrial machinery, while the opposite side is sometimes fixed to the rotating component. In this case, if the insertion component slides relative to the hollow portion due to the relative rotation of the base component and the rotating component, it will cause wear and tear on the insertion component.

[0004] As a countermeasure, Patent Document 1 discloses a deceleration device in which the position of a protective member (one-side end member) of the base side end of the hollow portion, through which the insertion member is inserted, is fixed relative to the base member. Thus, when the base member and the rotating member rotate relative to each other, sliding of the base side portion of the insertion member relative to the base side end of the hollow portion can be prevented.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2010-156431 The protective component in Patent Document 1 is configured to overflow radially outward relative to the outer periphery of the wheel frame of the reduction gear. The inventors have conducted research and discovered that, from the viewpoint of achieving a lighter reduction gear, the technology in Patent Document 1 has room for improvement. Summary of the Invention

[0006] One embodiment of the present invention was made in view of this situation, and one of its objectives is to provide a technology that enables the lightweighting of the deceleration device.

[0007] One embodiment of the present invention relates to a speed reduction device comprising: a housing on which an internal gear is disposed; an external gear meshing with the internal gear; and a wheel carrier disposed on the axial side of the external gear and rotatably supported on the housing, wherein the speed reduction device has a hollow portion extending axially through its radial center, wherein the speed reduction device comprises: a central tube inserted through the external gear and the wheel carrier and forming the hollow portion; and a protective member disposed axially adjacent to the end of the central tube and forming the end of the hollow portion, the protective member being fixed to the wheel carrier, and the protective member being configured such that it lies radially inward relative to the circumscribed circle of the largest diameter circumscribed around the central axis of the internal gear and circumscribed outside the wheel carrier.

[0008] According to the present invention, the speed reduction device can be made lightweight. Attached Figure Description

[0009] Figure 1 This is a cross-sectional view showing a part of an industrial machine that uses the speed reduction device of the first embodiment.

[0010] Figure 2 This is a schematic diagram showing the protective components and the base-side wheel frame when viewed from the base side.

[0011] Figure 3 yes Figure 1 A magnified view of a portion of the image.

[0012] Figure 4 This is a cross-sectional view showing a portion of the deceleration device in the first modified example.

[0013] Figure 5 This is a cross-sectional view showing a portion of the deceleration device according to the second embodiment.

[0014] Figure 6 This is a cross-sectional view showing a part of an industrial machine that uses the speed reduction device of the third embodiment.

[0015] In the diagram: 10-reduction gear, 20-motor, 24-hollow part, 30-crankshaft, 30c-hollow part, 32-external gear, 34-internal gear, 36-wheel frame, 40-housing, 42-center tube, 44-protective component, 44a-hollow structural part, 46-cover component, 60-washer. Detailed Implementation

[0016] In the following embodiments and variations, the same symbols will be used to refer to the same constituent elements, and repeated descriptions will be omitted. Furthermore, in each drawing, for ease of explanation, a portion of the constituent elements will be omitted, or the dimensions of the constituent elements will be appropriately enlarged or reduced.

[0017] (First Embodiment) Figure 1 This is a cross-sectional view showing a portion of an industrial machine 12 using the reduction gear 10 of the first embodiment. The industrial machine 12 is an industrial robot, and the reduction gear 10 drives its joints. Furthermore, the application of the reduction gear 10 of the present invention is not particularly limited. The industrial machine 12 includes a base member 14 (first target member) on the base end side, a rotating member 16 (second target member) on the front end side, and a drive device 18 that rotates the rotating member 16 relative to the base member 14. Figure 1 A portion of the base member 14 is shown. In this embodiment, the rotating member 16 is configured as part of the same component as the cover member 46 (described later) of the speed reduction device 10. The drive device 18 of this embodiment rotates the rotating member 16 in a manner that reciprocates relative to the base member 14 within a predetermined angular range. Furthermore, the rotating member 16 (the second object member) is sometimes provided as a different component from the cover member 46 and is fixed to a flange portion that protrudes radially outward from the housing 40.

[0018] The drive unit 18 includes a power supply (not shown), a motor 20, a reduction gear 10, and a connecting member 22. The power supply is mounted on the base member 14 (or on a member that does not rotate relative to the base member 14). The motor 20 is mounted on the rotating member 16 and drives driven components such as the external gear 32 of the reduction gear 10. The reduction gear 10 uses the power of the motor 20 to cause the rotating member 16 to rotate relative to the base member 14.

[0019] The insertion member 22 is an elongated member having a first side portion (hereinafter referred to as the base side portion 22a) located on one side in the length direction and a second side portion (hereinafter referred to as the base opposite side portion 22b) located on the other side in the length direction opposite to the base side portion 22a. In this embodiment, the insertion member 22 is a cable that supplies power from a power source to the motor 20. The base side portion 22a of the insertion member 22 is fixed to the base member 14 via the power source, and the base opposite side portion 22b is fixed to the rotating member 16 via the motor 20. Furthermore, the base opposite side portion 22b in this embodiment has a first branch portion 22c and a second branch portion 22d that branch at a midway point; the first branch portion 22c is fixed to the rotating member 16.

[0020] The reduction gear 10 is provided with a hollow portion 24 through which the insertion member 22 is inserted. The hollow portion 24 is provided through the reduction gear 10 along the axial direction X at its radial center (described later). The hollow portion 24 has one side located along the axial direction X (…). Figure 1The hollow portion 24 has a base-side end 24a (hereinafter referred to as the base-side end 24a) on one side and a base-opposite end 24b (hereinafter referred to as the base-opposite end 24b) on the other side in the axial direction X. A base-side portion 22a of a insertion member 22 is inserted into the base-side end 24a of the hollow portion 24, and a base-opposite portion 22b of the insertion member 22 is inserted into the base-opposite end 24b.

[0021] The reduction gear 10 causes the external gear 32, which meshes with the internal gear 34, to oscillate, thereby causing one of the internal gear 34 and the external gear 32 to rotate, and this rotational component can be output from the output component. In this embodiment, the output component is the housing 40, described later. The reduction gear 10 of this embodiment is an eccentric oscillating type reduction gear that generates the aforementioned rotational component through the oscillation of the external gear 32. The reduction gear 10 of this embodiment is a center crank type reduction gear with the crankshaft 30 positioned at the central axis La of the internal gear 34.

[0022] Hereinafter, the direction along the central axis La of the internal gear 34 will be defined as axial X. Furthermore, for ease of explanation, one side of axial X ( Figure 1 The lower side of the inner gear 34 is called the base side (protective component side), and the other side in the axial direction X is called the opposite side of the base (opposite side of the protective component). Furthermore, the circumferential direction and the radial direction of the circle centered on the central axis La of the inner gear 34 are referred to as "circumferential" and "radial" respectively.

[0023] The speed reduction device 10 mainly includes: an input shaft 26; a transmission gear 28; a crankshaft 30; an external gear 32; an internal gear 34; wheel frames 36 and 38; a housing 40; a central tube 42; a protective component 44; and a cover component 46. Many features of the speed reduction device 10 in this embodiment are found in the central tube 42, the protective component 44, and the cover component 46; however, the description will begin with its peripheral structure.

[0024] The input shaft 26 is configured to be connected to the motor shaft 20a of the motor 20 via a spline or the like, so that it can rotate integrally with the motor shaft 20a of the motor 20. An external toothed portion is formed on the outer periphery of the input shaft 26, which meshes with the transmission gear 28.

[0025] The transmission gear 28 can transmit the rotation of the input shaft 26 to the crankshaft 30. The transmission gear 28 is configured to be connected to the crankshaft 30 by threaded components or the like, so that it can rotate integrally with the crankshaft 30.

[0026] The crankshaft 30 is capable of rotating about its own rotation centerline Lb, and this rotation causes the external gear 32 to oscillate. The crankshaft 30 has a shaft portion 30a extending along the axial direction X, a plurality of (two in this embodiment) eccentric portions 30b arranged in a manner that allows them to rotate integrally with the shaft portion 30a, and a hollow portion 30c extending along the axial direction X through the shaft portion 30a. The central axes of the plurality of eccentric portions 30b are eccentric relative to the rotation centerline Lb of the crankshaft 30. The eccentric phases of the plurality of eccentric portions 30b are staggered from each other; in this embodiment, the eccentric phases of two eccentric portions 30b are staggered from each other by 180 degrees.

[0027] A plurality of external gears 32 are provided corresponding to each eccentric portion 30b of the crankshaft 30, and are arranged at intervals along the axial direction X. Each external gear 32 has a central hole 32a through which the crankshaft 30 passes. The external gear 32 is located radially outward of the corresponding eccentric portion 30b of the crankshaft 30 and is rotatably supported on the eccentric portion 30b via an eccentric bearing 48. The external gear 32 oscillates by rotating about its own central axis around the rotation center line Lb via the corresponding eccentric portion 30b of the crankshaft 30.

[0028] An internal gear 34 is disposed radially outside a plurality of external gears 32, and has internal teeth that mesh with the external teeth of the external gears 32. In this embodiment, the number of internal teeth of the internal gear 34 is one more than the number of teeth of the external gears 32.

[0029] Wheel carriers 36 and 38 are disposed on the axial side of the external gears 32. The wheel carriers 36 and 38 include: a base-side wheel carrier 36 (first wheel carrier) disposed on the base side relative to the plurality of external gears 32, and a base-opposite-side wheel carrier 38 (second wheel carrier) disposed on the opposite side of the base. The wheel carriers 36 and 38 are rotatably supported on the housing 40 via a main bearing 50. Alternatively, one of the wheel carriers 36 and 38 may be omitted, for example, the base-opposite-side wheel carrier 38.

[0030] In this embodiment, the wheel carriers 36 and 38 are disc-shaped. The wheel carriers 36 and 38 have through holes 52 extending through their radial center. The wheel carriers 36 and 38 support the crankshaft 30, which is disposed within the through holes 52, so that it can rotate freely via crankshaft bearings 54.

[0031] The base-side wheel carrier 36 and the base-opposite-side wheel carrier 38 are configured to be connected to each other via wheel carrier pins (inner pins) 56 that pass through a plurality of external gears 32, thereby enabling them to rotate as a whole. The wheel carrier pin 56 is integrally formed with one of the wheel carriers in the base-side wheel carrier 36 or the base-opposite-side wheel carrier 38, and is connected to the other wheel carrier by threaded components or the like, thereby enabling it to rotate as a whole with the other wheel carrier.

[0032] The aforementioned internal gear 34 is provided on the inner periphery of the outer casing 40. The outer casing 40 is cylindrical in shape, and internal components such as the external gear 32, wheel frame 36, and 38 are arranged radially inside it. In this embodiment, the outer casing 40 serves as an output component that rotates synchronously with the internal gear 34 when it rotates, thereby outputting the rotation component to the rotating component 16. The outer casing 40 is connected to the rotating component 16 (cover component 46) via threaded components or the like.

[0033] The operation of the aforementioned speed reduction device 10 will now be explained.

[0034] If the input shaft 26 rotates based on the power output from the motor, this power is transmitted to the crankshaft 30 via the transmission gear 28 to cause the crankshaft 30 to rotate. If the crankshaft 30 rotates about the rotation center line Lb, the external gear 32 oscillates through the crankshaft 30. At this time, the external gear 32 oscillates in such a way that it rotates about the rotation center line Lb with its own central axis. If the external gear 32 oscillates in this way, the meshing position of the external gear 32 and the internal gear 34 shifts sequentially. As a result, each time the crankshaft 30 rotates, one of the external gear 32 and the internal gear 34 will rotate by an amount equivalent to the difference in the number of teeth between the external gear 32 and the internal gear 34. In this embodiment, since the wheel carriers 36 and 38 are fixed to the base member 14, the internal gear 34 rotates, and this rotational component is output from the output member (i.e., the housing 40). The rotation of the crankshaft 30 is reduced in speed by a reduction ratio corresponding to the difference in the number of teeth between the external gear 32 and the internal gear 34, and is output from the output member (i.e., the housing 40) to the rotating member 16. As a result, the rotating component 16 rotates relative to the base component 14.

[0035] Next, the main features of this embodiment will be described. The central tube 42 is inserted into the central hole 32a of the external gear 32 and the through holes 52 of the wheel carriers 36 and 38. Furthermore, the central tube 42 is also inserted into the hollow portion 30c of the crankshaft 30. The central tube 42 is positioned between the protective member 44 and the cover member 46. The central tube 42 forms the intermediate portion 24c of the hollow portion 24, between the base-side end 24a and the base-opposite end 24b.

[0036] The protective member 44 is positioned adjacent to the end of the central tube 42 on the base side in the axial direction X. The protective member 44 is fixed to the base-side wheel bracket 36 by means of threaded components or the like. The protective member 44 is fixed to the base member 14 via the base-side wheel bracket 36, and its position relative to the base member 14 is fixed. The protective member 44 has a first hollow structural portion 44a that forms the base-side end portion 24a of the hollow portion 24.

[0037] The cover member 46 is positioned adjacent to the end opposite to the base of the central tube 42 in the axial direction X. The cover member 46 covers the wheel frame 38 opposite to the base from the opposite side of the base. The cover member 46 is fixed to the housing 40 by threaded components or the like, thereby becoming integrated with the housing 40. In this embodiment, the cover member 46 is configured as part of the same component as the rotating member 16, and its position relative to the rotating member 16 is fixed.

[0038] The cover member 46 has a second hollow structure portion 46a through which the insertion member 22 is inserted and which forms the opposite end 24b of the hollow portion 24. The cover member 46 also includes: a cylindrical input shaft support portion 46b that protrudes towards the opposite side of the base at a position radially outwardly offset relative to the second hollow structure portion 46a; and a motor fixing portion 46c disposed at the front end of the input shaft support portion 46b. The motor shaft 20a and the input shaft 26 are inserted into the inside of the input shaft support portion 46b. The input shaft support portion 46b supports the input shaft 26 for rotational movement via an input bearing 58. The motor fixing portion 46c abuts against the flange of the motor 20 and fixes the motor 20 by a threaded component (not shown).

[0039] Here, it is necessary to prevent the insertion member 22 and the hollow portion 24 from sliding against each other as the rotating member 16 rotates relative to the base member 14. Such sliding typically occurs at the base-side end 24a or the opposite end 24b of the hollow portion 24. The base-side portion 22a of the insertion member 22, which is inserted into the base-side end 24a of the hollow portion 24, is fixed relative to the base member 14. Similarly, the base-opposite portion 22b of the insertion member 22, which is inserted into the opposite end 24b of the hollow portion 24, is fixed relative to the rotating member 16. Therefore, to avoid the aforementioned sliding, the deceleration device 10 of this embodiment is configured to satisfy the following two conditions.

[0040] The first condition is as follows: the protective member 44 of the base-side end 24a constituting the hollow portion 24 is fixed in position relative to the base member 14 (the protective member 44 and the base member 14 will not rotate relative to each other). For example, as mentioned above, this condition can be achieved by fixing the base-side wheel frame 36 to which the protective member 44 is fixed to the base member 14. The second condition is as follows: the cover member 46 of the opposite-side end 24b constituting the hollow portion 24 is fixed in position relative to the rotating member 16. For example, as mentioned above, this condition can be achieved by making the cover member 46 part of the same component as the rotating member 16 or by fixing the cover member 46 to the rotating member 16.

[0041] Figure 2 This is a schematic diagram showing the protective component 44 and the base-side wheel frame 36 as viewed from the base side. Figure 2In the diagram, the base-side wheel frame 36 is shaded. The protective member 44 is configured such that it falls radially inward relative to the outer peripheral surface of the base-side wheel frame 36 to which the protective member 44 is fixed. Specifically, as... Figure 2 and Figure 3 As shown, the protective component 44 is configured such that its circumscribed circle Ca, with respect to the maximum diameter Ra centered on the central axis La of the internal gear 34 and circumscribed outside the base-side wheel carrier 36, lies radially inward. The protective component 44 can also be understood as being configured not to overflow radially outward relative to this circumscribed circle Ca. This can also be understood as: viewed from the axial X (from...) Figure 2 When viewed from a certain perspective, the protective member 44 is configured such that its outer peripheral surface, relative to the shape of the base-side wheel frame 36, falls radially inward. Therefore, compared to the reduction gear in Patent Document 1, where the protective member 44 is configured to overflow radially outward relative to the outer peripheral surface of the wheel frames 36, 38, the radial size of the protective member 44 can be reduced, and this reduction in size enables the reduction gear 10 to be made lighter.

[0042] Furthermore, the cover member 46 is configured to overflow radially outward relative to the circumcircle (not shown) of the largest diameter circumscribed outside the outer peripheral surface of the protective member 44. In this embodiment, the cover member 46 is configured to overflow radially outward relative to the circumcircle (not shown) of the largest diameter circumscribed outside the outer peripheral surface of the wheel frame 38 opposite to the base.

[0043] Next, other features of the speed reduction device 10 will be described.

[0044] Figure 3 yes Figure 1 A partial enlarged view. The base-side wheel carrier 36 has a wheel carrier-side locking portion 36a for mounting the base component 14. The base component 14 has an object-side locking portion 14a that fits into the wheel carrier-side locking portion 36a. The wheel carrier-side locking portion 36a and the object-side locking portion 14a are respectively provided at portions of the base component 14 and the base-side wheel carrier 36 that are opposite to each other in the axial direction X. In this embodiment, the wheel carrier-side locking portion 36a is convex in shape protruding towards the base side, and the object-side locking portion 14a is concave in shape recessed towards the base side. In this embodiment, the object-side locking portion 14a is part of a through hole penetrating the base component 14 along the axial direction X, and a protective member 44 and a insertion member 22 are disposed inside it.

[0045] (A) such as Figure 2 and Figure 3As shown, the protective member 44 is configured such that its outer peripheral surface falls radially inward relative to the outer peripheral surface of the convex wheel frame side locking portion 36a. Here, the outer peripheral surface of the wheel frame side locking portion 36a refers to the surface that contacts the inner peripheral surface of the object-side locking portion 14a that engages with the wheel frame side locking portion 36a. Therefore, it can also be understood that, when viewed from the axial direction X, the protective member 44 is configured such that its outer peripheral surface, which forms the shape of the wheel frame side locking portion 36a, falls radially inward. This allows for further miniaturization of the radial dimension of the protective member 44.

[0046] In addition, such as Figure 4 As shown, the wheel frame side locking portion 36a can also be concave, recessed towards the opposite side of the base, and the object side locking portion 14a can also be convex, protruding towards the opposite side of the base. In this case, to achieve the effect described in (A), the protective member 44 can be configured such that its inner circumferential surface falls radially inward relative to the inner circumferential surface of the wheel frame side locking portion 36a. Here, the inner circumferential surface of the wheel frame side locking portion 36a refers to the surface that contacts the outer circumferential surface of the object side locking portion 14a that engages with the wheel frame side locking portion 36a. Therefore, it can also be understood that, when viewed from the axial direction X, the protective member 44 is configured such that its inner circumferential surface, which forms the shape of the wheel frame side locking portion 36a, falls radially inward.

[0047] return Figure 1 The protective component 44 is made of a material with a lower hardness than the central tube 42. Here, hardness refers to Vickers hardness [Hv]. Specifically, the central tube 42 is made of aluminum-based materials, including aluminum alloys (i.e., a metallic material), while the protective component 44 is made of a synthetic resin (i.e., a resin material) with a lower hardness than the metallic material of the central tube 42. The synthetic resin here is, for example, a general-purpose engineering plastic such as polycarbonate. The protective component 44 uses a low-hardness material, which is lower than the hardness of the central tube 42 made of a high-hardness material. Therefore, compared to the case where the insertion component 22 is in contact with a high-hardness material, the burden on the insertion component 22 in contact with the protective component 44 can be reduced, and wear on the insertion component 22 can be effectively prevented.

[0048] Furthermore, the base side wheel frame 36 is made of ferrous materials (i.e., metallic materials), including cast iron and steel, while the protective component 44 is made of a resin material with a lower hardness than the metal of the base side wheel frame 36. In other words, the protective component 44 is made of a material with a lower hardness than the base side wheel frame 36.

[0049] Furthermore, the motor 20, which drives the external gear 32 of the reduction gear 10, is not fixed to the protective member 44 but to the cover member 46. Therefore, it is not necessary to use the protective member 44 to ensure the strength required to fix the motor 20, thus reducing the strength required for the protective member 44 and making it easier to miniaturize and lighten the protective member 44.

[0050] The first hollow structural portion 44a of the protective member 44 has a first inner diameter changing portion 44b whose inner diameter gradually increases towards the axially outward direction. The first inner diameter changing portion 44b forms an opening edge at the end located on the base side of the hollow portion 24. The second hollow structural portion 46a of the cover member 46 has a second inner diameter changing portion 46d whose inner diameter gradually increases towards the axially outward direction. The second inner diameter changing portion 46d forms an opening edge at the end located on the opposite side of the base of the hollow portion 24. The first inner diameter changing portion 44b and the second inner diameter changing portion 46d are curved. The first inner diameter changing portion 44b and the second inner diameter changing portion 46d have the following function: increasing the contact area when the insertion member 22 contacts the opening edge of the hollow portion 24, thereby preventing the insertion member 22 from being worn due to the increase in local surface pressure. Alternatively, the first inner diameter changing portion 44b and the second inner diameter changing portion 46d may not be curved, but rather be a surface whose inner diameter changes linearly.

[0051] The first hollow structural portion 44a of the protective member 44 has a first straight portion 44c with a constant inner diameter formed on the axially inner side (the external gear side in the axial direction) compared to the first inner diameter changing portion 44b. The second hollow structural portion 46a of the cover member 46 has a second straight portion 46e with a constant inner diameter formed on the axially inner side compared to the second inner diameter changing portion 46d. The inner diameters of the first straight portion 44c and the second straight portion 46e are the same as the inner diameter of the central tube 42.

[0052] like Figure 3 As shown, the speed reduction device 10 also includes a washer 60 externally embedded in the central tube 42. In this embodiment, the washer 60 is made of ferrous materials, including carbon steel (i.e., metallic materials). The washer 60 is a cylindrical component that is externally embedded in the central tube 42 through an interference fit, a transition fit, or the like.

[0053] The central tube 42 has a washer mounting portion 42a for mounting a washer 60 and an intermediate portion 42b located adjacent to the washer mounting portion 42a on the opposite side of the base. The washer mounting portion 42a is located at the base-side end of the central tube 42. The inner diameter of the washer mounting portion 42a is the same as the inner diameter of the intermediate portion 42b, while its outer diameter is smaller than the outer diameter of the intermediate portion 42b.

[0054] The reduction gear 10 also includes a first oil seal 62 disposed between the center tube 42 and the base-side wheel frame 36. The first oil seal 62 is disposed between the washer 60 externally embedded in the center tube 42 and the base-side wheel frame 36. The first oil seal 62 is installed in the sealing element mounting portion 36b provided in the base-side wheel frame 36 by means of interference fit, transition fit, etc. The sealing element mounting portion 36b forms the base-side end of the through hole 52 of the base-side wheel frame 36.

[0055] The first oil seal 62 has a sealing lip 62a that contacts the outer peripheral surface of the gasket 60 based on elastic deformation. The first oil seal 62 seals the internal space 64 formed on the radially inner side of the housing 40 through the contact between the sealing lip 62a and the gasket 60. Lubricating oil (not shown) for lubricating the meshing parts of gears such as the external gear 32 and the internal gear 34, as well as bearings such as the eccentric bearing 48, is sealed in this internal space 64.

[0056] Here, at the location in contact with the sealing lip 62a of the first oil seal 62, it is necessary to ensure the hardness required to prevent wear caused by the sliding of the sealing lip 62a. The center tube 42 is made of aluminum for weight reduction; however, using aluminum makes it difficult to ensure the necessary hardness. Therefore, a gasket 60 made of ferrous material, whose hardness can be easily ensured through heat treatment, is externally fitted into the center tube 42, and the first oil seal 62 is positioned between the gasket 60 and the wheel carriers 36 and 38. Thus, compared to a center tube 42 with an aluminum component at the location in contact with the first oil seal 62, it is easier to ensure the necessary hardness at the location in contact with the first oil seal 62.

[0057] The outer diameter Rb of the aforementioned washer 60 is set to be smaller than the inner diameter Rc of the hollow portion 30c of the crankshaft 30. Here, the inner diameter Rc of the crankshaft 30 refers to the smallest inner diameter within the entire axial X range of the crankshaft 30. Furthermore, the outer diameter Rb of the washer 60 is set to be smaller than the central hole 28a formed in the transmission gear 28 (see reference). Figure 1 The inner diameter of (). Its advantages are explained below.

[0058] Consider the case where the center tube 42 is pulled out from the hollow portion 30c of the crankshaft 30 towards the base in the axial direction X for maintenance or other purposes. In this case, according to the above structure, even when the center tube 42 is pulled out with the washer 60 installed, the washer 60 is unlikely to be jammed by the crankshaft 30. Therefore, during the removal of the center tube 42, it is not necessary to remove the washer 60 from the center tube 42, resulting in good operability.

[0059] Furthermore, in this embodiment, the outer diameter Rb of the washer 60 is set to be smaller than the outer diameter Rd of the middle portion 42b of the center tube 42. Therefore, it has the advantage that the washer 60 is less likely to be jammed by the crankshaft 30 during the removal operation of the center tube 42.

[0060] The protective component 44 is generally disc-shaped. The protective component 44 has: a fixing portion 44d, an end portion overlapping and fixed to the base-side wheel frame 36 along the axial direction X; and an inner portion 44e, facing inward along the axial direction X. The inner portion 44e of the protective component 44 is positioned opposite the first oil seal 62, the washer 60, and the central tube 42 along the axial direction X. The inner portion 44e of the protective component 44 is positioned with a gap 66 between it and the first oil seal 62, the washer 60, and the central tube 42, thus preventing contact with them. The gap 66 between the inner portion 44e of the protective component 44 and the first oil seal 62 functions as clearance. This clearance prevents contact between the two if the first oil seal 62 shifts from a predetermined target position towards the protective component 44 due to dimensional errors, etc. The target position here is set at the position where the first oil seal 62 does not overflow from the axially outer opening edge 36c of the seal mounting portion 36b of the base-side wheel frame 36. Furthermore, offset from the target position refers to the situation where the first oil seal 62 overflows axially from the opening edge 36c of the seal mounting portion 36b.

[0061] Therefore, if the first oil seal 62 shifts from its target position, causing the protective member 44 to come into contact with it, it may be impossible to secure the protective member 44 to the base-side wheel frame 36. Considering this, the protective member 44 of this embodiment is positioned at a gap 66 that separates it from the first oil seal 62, creating a clearance. Thus, when the first oil seal 62 shifts from its target position, it is easy to prevent the protective member 44 from coming into contact with it, and it is easy to avoid the situation where such contact would prevent the protective member 44 from being secured to the base-side wheel frame 36.

[0062] The inner surface 44e of the protective member 44 has: a first inner surface portion 44f, at least a portion of which faces the first oil seal 62 in the axial direction X; and a second inner surface portion 44g, which faces the central tube 42 in the axial direction X. The first inner surface portion 44f is located radially inward than the fixing portion 44d of the protective member 44. The second inner surface portion 44g is located radially inward than the first inner surface portion 44f. The second inner surface portion 44g is located axially outward (on the side opposite to the external gear and the side opposite to the wheel carrier in the axial direction) than the first inner surface portion 44f. The first inner surface portion 44f is configured to be spaced apart from the first oil seal 62 by a first gap 66a. The second inner surface portion 44g is configured to be spaced apart from the central tube 42 by a second gap 66b.

[0063] The axial dimension L1 of the first gap 66a is set to be smaller than the axial dimension L2 of the second gap 66b. The protective member 44 has a portion (first inner surface portion 44f) where the axial dimension L1 of the gap between it and the first oil seal 62 is smaller than the axial dimension L2 of the gap between it and the central tube 42. In other words, the minimum axial gap L1 between the protective member 44 and the first oil seal 62 is smaller than the minimum axial gap L2 between the protective member 44 and the central tube 42. Its advantages will be explained below.

[0064] The following considers a scenario where the hollow structural portion 44a of the protective member 44 deforms in the axial inward direction Pa due to external force caused by contact with the insertion member 22, etc. In this case, according to the above structure, the protective member 44 contacts the first oil seal 62 before contacting the central tube 42. Therefore, even if the protective member 44 is deformed as described above, it is possible to prevent the protective member 44 from contacting the central tube 42, which rotates at high speed when the base member 14 and the rotating member 16 rotate relative to each other.

[0065] like Figure 1 As shown, the cover component 46 is connected to the end 42c of the central tube 42 opposite to the base (opposite to the protective component). The cover component 46 and the central tube 42 are integrally formed from die-cast aluminum or the like. Therefore, the central tube 42 is configured to rotate integrally with the cover component 46. The cover component 46 and the central tube 42 are composed of a single component. This reduces the number of components, thereby reducing management costs, and reduces assembly time, thereby alleviating the burden on assembly labor.

[0066] (Second Implementation) Figure 5 This is a cross-sectional view showing a portion of the speed reduction device 10 according to the second embodiment. The speed reduction device 10 of this embodiment is similar to... Figure 3 The difference in the example lies in washer 60. Figure 3 In the previous example, an example was described where the outer diameter of the washer 60 was smaller than the inner diameter of the hollow portion 30c of the crankshaft 30. In this embodiment, the outer diameter of the washer 60 is larger than the inner diameter of the hollow portion 30c of the crankshaft 30. Thus, the outer diameter of the washer 60 is not particularly limited.

[0067] (Third implementation) Figure 6 This is a cross-sectional view showing a portion of an industrial machine 12 using the speed reduction device 10 of the third embodiment. Figure 1 In the previous example, an example was described where the cover component 46 and the central tube 42 were composed of a single component. In this embodiment, the cover component 46 and the central tube 42 are formed separately. The cover component 46 and the central tube 42 are integrated by means of threaded components or the like.

[0068] In detail, the cover member 46 has a recess 46f that is disposed on the base side relative to the second hollow structure portion 46a and recessed axially outward. The central tube 42 has an insert portion 42d disposed at the end opposite to the base of the central tube 42 and embedded in the recess 46f of the cover member 46. The central tube 42 is fixed to the cover member 46 by a threaded member 68 that is fastened through the second hollow structure portion 46a and the insert portion 42d of the cover member 46.

[0069] The embodiments of the present invention have been described in detail above. These embodiments are merely specific examples for implementing the present invention. The content of the embodiments does not limit the technical scope of the present invention; various design changes, such as alterations, additions, and deletions of constituent elements, can be made without departing from the inventive spirit defined in the claims. In the above embodiments, such design changes are described using terms such as "in the embodiment" or "in the embodiment," but this does not mean that design changes are not permitted without such descriptions. Furthermore, the shaded lines in the cross-sectional views of the drawings do not limit the material of the objects marked with shaded lines.

[0070] The above describes an example of a first-stage joint member (rotating member 16) driven by the drive device 18, which is adjacent to the base member at the far end of the robotic arm. Furthermore, the drive device 18 can also be used to drive joint members at the second stage and beyond. In this case, the joint member being driven can be considered a rotating member, and the joint member adjacent to the driven joint member at the far end can be considered a base member. Based on the relationship between the joint member at the far end and another base member adjacent at a further far end, the joint member at the far end becomes a rotating member, which rotates relative to that other base member.

[0071] The above description illustrates an example where the rotating component 16 of the industrial machinery 12 is configured as part of the same component as the cover component 46 of the speed reduction device 10. However, the rotating component 16 may also be configured separately from the cover component 46. Furthermore, the above description illustrates an example where the motor 20 of the drive device 18 is fixed to the cover component 46. However, the motor 20 may also be fixed to the protective component 44.

[0072] The above description illustrates an example where the plug-in component 22 is a power cable; however, the specific example is not particularly limited. The plug-in component 22 could also be other cables such as wiring cables, or it could be a cooling pipe through which coolant flows, a drive shaft, etc.

[0073] The above description addresses the case where the reduction gear 10 is an eccentric oscillating type reduction gear; however, its type is not particularly limited. For example, it could also be a flexural meshing type reduction gear, a planetary gear reduction gear, etc. Furthermore, the above description also addresses the example of an eccentric oscillating type reduction gear being a center crank type reduction gear; however, its type is not particularly limited. For example, it could also be a distribution type reduction gear in which multiple crankshafts are arranged radially outward from the central axis La of the internal gear 34.

[0074] In this embodiment, an example is described where the external gear 32 is oscillated, causing the internal gear 34 to rotate and the rotation component is output from the housing 40, which is an output component. Alternatively, the external gear 32 can be oscillated, causing it to rotate and the rotation component can be output from the wheel carriers 36 and 38.

[0075] The above description illustrates an example where the protective member 44 forms the base-side end 24a of the hollow portion 24 through which the base-side portion 22a of the insertion member 22 is inserted. Alternatively, the protective member 44 may also form the base-side end 24b of the hollow portion 24 through which the base-opposite portion 22b of the insertion member 22 is inserted.

[0076] Furthermore, when using the protective member 44, it is preferable to avoid slippage between the protective member 44 and the hollow portion 24 and the insertion member 22 due to the relative rotation of the base member 14 and the rotating member 16 (however, this is not a limitation). To achieve this, when the protective member 44 forms the base-side end 24a of the hollow portion 24, in order to fix the position of the protective member 44 relative to the base member 14, it is preferable to also fix the position of the base-side wheel frame 36, on which the protective member 44 is fixed, relative to the base member 14. At this time, with the wheel frames 36 and 38 of the reduction gear 10 fixed to the base member 14, the housing 40 of the reduction gear 10 is rotated by the power of the motor 20, thereby causing the rotating member 16 to rotate.

[0077] Furthermore, in order to achieve the above objectives, when the protective member 44 forms the opposite end 24b of the hollow portion 24, in order to fix the position of the protective member 44 relative to the rotating member 16, it is preferable to also fix the position of the wheel frame 38 opposite to the base of the protective member 44 relative to the rotating member 16. At this time, with the housing 40 of the reduction gear 10 fixed to the base member 14, the wheel frames 36 and 38 of the reduction gear 10 are rotated by the power of the motor 20, thereby causing the rotating member 16 to rotate.

[0078] That is, when the protective member 44 forms the base-side end 24a of the hollow portion 24, the protective member 44 can be fixed on the wheel frames 36, 38 fixed to the base member 14, thereby fixing the position of the protective member 44 relative to the base member 14. On the other hand, when the protective member 44 forms the base-side end 24b of the hollow portion 24, the protective member 44 can be fixed on the wheel frames 36, 38 that rotate based on the motor 20, thereby fixing the position of the protective member 44 relative to the rotating member 16.

[0079] The protective component 44 only needs to be configured such that the circumscribed circle Ca of the maximum diameter Ra circumscribed with the outer peripheral surface of the base-side wheel frame 36 falls radially inward, and its radial dimension is not particularly limited. For example, as long as this condition is met, the protective component 44 can also be configured to overflow radially outward relative to the outer peripheral surface or inner peripheral surface of the wheel frame-side locking portion 36a of the base-side wheel frame 36.

[0080] The above description illustrates an example where the protective component 44 is made of a material with a lower hardness than the central tube 42; however, the hardness of this material is not particularly limited. Similarly, the above description illustrates an example where the central tube 42 is made of an aluminum-based material and the washer 60 is made of an iron-based material; however, the materials are not particularly limited.

[0081] The above describes an example of the first oil seal 62 being positioned between the first wheel carrier 36 and the washer 60. However, the washer 60 is not a necessary component. In this case, the first oil seal 62 only needs to be positioned between the first wheel carrier 36 and the center tube 42.

[0082] The above description illustrates an example where the protective component 44 is configured not to contact the first oil seal 62. However, the protective component 44 may also be configured to contact the first oil seal 62. The above description also illustrates an example where the axial dimension L1 of the first gap 66a between the protective component 44 and the first oil seal 62 and the axial dimension L2 of the second gap 66b between the protective component 44 and the central tube 42 are different from each other. However, their relationship is not particularly limited.

[0083] In this embodiment, the outer shell 40 and the cover component 46 are respectively set as independent components. However, the outer shell 40 and the cover component 46 can also be formed into one unit by a single component.

Claims

1. A speed reduction device comprising: a housing on which an internal gear is disposed; an external gear meshing with the internal gear; and a wheel carrier disposed on the axial side of the external gear and rotatably supported on the housing, wherein the speed reduction device has a hollow portion extending axially through its radial center, characterized in that it comprises: A central tube, which overlaps with the entire axial region of the external gear when viewed radially, is inserted into the external gear and forms the hollow portion inserted into the wheel carrier; and A protective component is disposed on the axially outer side of the end of the central tube and forms the end of the hollow portion. The protective component is positioned radially inward of the circumscribed circle of the largest diameter circumscribed around the central axis of the internal gear and outside the wheel carrier, and does not support the central tube. The deceleration device also includes an oil seal, which is located radially outward of the central tube and axially inward than the protective component.

2. The speed reduction device according to claim 1, characterized in that, The protective component has an inner face that covers the space on the axially outer side of the oil seal from the axially outer side.

3. The speed reduction device according to claim 1 or 2, characterized in that, The inner surface of the protective component overlaps with the oil seal in the axial direction.

4. The speed reduction device according to claim 1 or 2, characterized in that, The inner surface of the protective component is axially opposed to the central tube and the oil seal. The inner surface includes a first inner surface portion opposite to the oil seal, and a second inner surface portion located radially inward than the first inner surface portion. The axial dimension between the first inner surface portion and the oil seal is smaller than the axial dimension between the second inner surface portion and the oil seal.

5. The speed reduction device according to claim 4, characterized in that, The second inner surface portion is also axially opposed to the central tube.

6. The speed reduction device according to claim 1 or 2, characterized in that, The protective component is made of a material with a lower hardness than the central tube.

7. The speed reduction device according to claim 1 or 2, characterized in that, The protective component has: The fixing part has an axial end face that is fixed to other components; and The opposing portion is located radially inside the fixed portion and is axially opposed to the oil seal and the central tube.

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