speed reducer

Abstract

This invention provides a gearbox that is advantageous in suppressing the jamming of foreign objects in the main lip portion, which is provided with multiple screw threads. [Solution] A reduction gear comprising a reduction mechanism having an external gear and an internal gear that mesh with each other, a case 16 having an internal space 32 inside that houses at least a part of the reduction mechanism, an internal member 18 disposed inside the case 16, and a seal body 38 disposed between the case 16 and the internal member 18, wherein one of the case 16 and the internal member 18 is an output member that outputs rotation, the seal body 38 comprises a main lip portion 58 that contacts a main seal surface 68 provided on one of the internal members which is one of the case 16 and the internal member 18, a plurality of screw portions 72 provided on the main lip portion 58 that increase the amount of fluid supplied to the internal space side in the axial direction when the case 16 and the internal member 18 rotate relative to each other, and a capture portion 76 capable of capturing foreign matter that is about to flow from the internal space 32 to the main lip portion 58 side.

Description

Technical Field

[0001] This disclosure relates to a speed reducer.

Background Art

[0002] Patent Document 1 discloses a speed reduction mechanism having externally meshing gears and internally meshing gears that mesh with each other, a case provided with an internal space for accommodating at least a part of the speed reduction mechanism on the inside, an inner member disposed inside the case, and a sealing body disposed between the case and the inner member. The sealing body of Patent Document 1 includes a main lip portion that contacts a main seal surface provided on the case, and a plurality of screw portions provided on the main lip portion that increase the amount of fluid fed into the internal space side in the axial direction when the case and the inner member rotate relative to each other.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Compare the case where a plurality of screw portions are provided on the main lip portion with the case where no plurality of screw portions are provided on the main lip portion. In the former case, compared with the latter case, at the contact portion of the main lip portion with the main seal surface, the contact area is smaller, and there is a tendency for high surface pressure to occur. Also, in the internal space of the speed reducer, due to the meshing of the components of the speed reduction mechanism, there is a specific situation where wear powder is likely to occur as foreign matter.

[0005] Let's consider the case where foreign matter generated in the internal space of the gearbox enters and gets caught between the main lip portion, which has multiple threaded sections as described above, and the main seal surface. In this case, the main lip portion, which generates high surface pressure, makes it easy for the foreign matter to remain caught, and the main lip portion is easily worn down by being pressed against the foreign matter. As a result, these effects make the contact state of the main lip portion with the main seal surface unstable, increasing the risk of lubricant leakage. In other words, when the main lip portion has multiple threaded sections, there is a problem that the contact state of the main lip portion with the main seal surface is easily unstable due to the effect of foreign matter generated in the internal space getting caught.

[0006] One of the purposes of this disclosure is to provide a gearbox that is advantageous in suppressing the jamming of foreign matter in the main lip portion, which is provided with multiple screw threads. [Means for solving the problem]

[0007] The speed reducer of the present disclosure comprises a reduction mechanism having an external gear and an internal gear that mesh with each other, a case having an internal space inside that houses at least a part of the reduction mechanism, an internal member disposed inside the case, and a seal body disposed between the case and the internal member, wherein one of the case and the internal member is an output member that outputs rotation, and the seal body comprises a main lip portion that contacts a main seal surface provided on one of the two members, the case and the internal member, a plurality of screw portions provided on the main lip portion that increase the amount of fluid supplied to the internal space in the axial direction when the case and the internal member rotate relative to each other, and a capture portion capable of capturing foreign matter that is about to flow from the internal space to the main lip portion. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide a speed reducer that is advantageous in suppressing the jamming of foreign matter in the main lip portion, which is provided with multiple screw portions. [Brief explanation of the drawing]

[0009] [Figure 1] This is a side cross-sectional view showing a speed reducer according to the first embodiment. [Figure 2] This is a magnified view of the area around the seal in Figure 1. [Figure 3] This is a side cross-sectional view showing a seal body of the first embodiment. [Figure 4] This is a view of the gearbox of the second embodiment from the same viewpoint as in Figure 2. [Figure 5] This is a side cross-sectional view showing a seal body of the second embodiment. [Modes for carrying out the invention]

[0010] Embodiments for implementing the speed reducer of this disclosure are described below. The same or equivalent elements are denoted by the same reference numerals, and redundant descriptions are omitted. For the sake of clarity, components are omitted, enlarged, or reduced as appropriate in each drawing. The drawings should be viewed in accordance with the orientation of the reference numerals.

[0011] (First Embodiment) Refer to Figure 1. In this specification, the direction along the rotational centerline C20 of the output member 20 of the reduction gear 10 is referred to as the axial direction, and the radial direction and circumferential direction with the rotational centerline C20 as the center of the circle are simply referred to as the radial direction and circumferential direction, respectively.

[0012] The reduction gear 10 is incorporated into the master machine. The master machine is, for example, at least part of various machines such as (1) industrial machinery such as machine tools and construction machinery, (2) robots such as industrial robots and service robots, (3) transport equipment such as conveyors, and (4) vehicles. The reduction gear 10 can drive a driven element that is part of the master machine by reducing the rotation input from the prime mover and outputting that rotation. The prime mover is, for example, a motor or engine.

[0013] The gearbox 10 comprises an input member 12 to which rotation output from the prime mover is input, a reduction mechanism 14 for reducing the rotation of the input member 12, a case 16 that houses at least a part of the reduction mechanism 14, and an inner member 18 disposed inside the case 16. In this embodiment, the inner member 18 becomes an output member 20 that outputs the rotation transmitted from the reduction mechanism 14 to the driven element. Alternatively, the case 16 may also serve as the output member 20.

[0014] The rotation of the prime mover may be input to the input member 12 via other power transmission members of the reduction gear 10, or it may be input directly. The reduction gear 10 in this embodiment uses a center crank type eccentric oscillating reduction mechanism 14. The reduction gear 10 using this includes a crankshaft 24 having eccentric portions 22 as the input member 12. The crankshaft 24 has at least one (three in this case) eccentric portions 22. The eccentric portions 22 have a circular shape that is eccentric with respect to the rotational center line of the crankshaft 24.

[0015] The reduction mechanism 14 has an external gear 26 and an internal gear 28 that mesh with each other. In this embodiment, the external gear 26 is provided corresponding to an eccentric portion 22 and is supported by the corresponding eccentric portion 22 via an eccentric bearing 30. In this embodiment, the external gear 26 is pivotable by the corresponding eccentric portion 22. In this embodiment, the internal gear 28 is provided on the inner circumference of the case 16. In this embodiment, the internal gear 28 comprises a gear body 28a which is also the case 16, and an internal tooth portion 28b provided on the gear body 28a. In this embodiment, the internal tooth portion 28b is composed of a pin that is rotatably supported by the gear body 28a. In addition, the internal tooth portion 28b may be composed of the same material as the gear body 28a. In addition, depending on the type of reduction mechanism 14, the entire internal gear 28 may be provided separately from the case 16.

[0016] An internal space 32 is provided inside the case 16. At least a part of the reduction mechanism 14 is housed in the internal space 32. In this embodiment, the external gear 26 of the reduction mechanism 14 is housed in the internal space 32. If the case 16 and the internal gear 28 are separate components, the internal space 32 may also house the internal gear 28 in addition to the external gear 26 of the reduction mechanism 14.

[0017] The internal space 32 forms at least part of a sealed space 34 in which lubricants such as lubricating oil and grease are enclosed. The lubricant is used at least for lubricating the reduction mechanism 14 housed in the internal space 32. In this embodiment, the sealed space 34 is also formed inside a motor adapter 36 that connects a motor (not shown) serving as a prime mover and the case 16. Thus, in addition to the internal space 32, the sealed space 34 may be continuous inside other members connected to the reduction gear 10. The other members forming the sealed space 34 are not particularly limited. Also, the sealed space 34 may be constituted only by the internal space 32.

[0018] The sealed space 34 is sealed at least by the sealing body 38. In addition to the sealing body 38, the sealed space 34 may be sealed by other sealing members 40A and 40B. In this embodiment, one sealing member 40A is constituted by a sealing cap or the like that closes a through-hole 18a formed in the inner member 18. Also, in this embodiment, the other sealing member 40B is also disposed between the case 16 and the motor adapter 36. In addition to this, in this embodiment, another sealing member (not shown) is also disposed between a motor shaft (not shown) connected to the input member 12 and the motor adapter 36. The number and type of the sealing body 38 and the sealing members 40 that seal the sealed space 34 are not particularly limited, and various ones may be applied according to the type of the reduction gearbox 10.

[0019] The inner member 18 is rotatable relative to the case 16 during the operation of the reduction gear 10. A main bearing 42 that supports the output member 20 is disposed between the case 16 and the inner member 18. The inner member 18 of this embodiment includes a first inner member 18A disposed on one axial side with respect to the reduction mechanism 14 and a second inner member 18B disposed on the other axial side. In this embodiment, the passive element is connected to the first inner member 18A by bolts or the like. The first inner member 18A and the second inner member 18B are connected by bolts or the like via a pin 44.

[0020] The inner member 18 of this embodiment is constituted by a carrier that can be synchronized with the rotation component of the external gear 26. Here, "synchronized with the rotation component" means maintaining the rotation components of the external gear 26 and the carrier to be of the same magnitude within a numerical range including zero. A pin 44 that penetrates the external gear 26 in the axial direction protrudes from the carrier. The pin 44 indirectly contacts the external gear 26 via a roller 46, enabling synchronization between the rotation component of the external gear 26 and the inner member 18. In addition to this, the pin 44 may directly contact the external gear 26.

[0021] An example of the operation of the speed reducer 10 described above will be explained. When the rotation output from the prime mover is input to the input member 12, the input member 12 rotates. When the input member 12 rotates, the rotation is decelerated by the speed reduction mechanism 14 and then transmitted to the output member 20, and is output from the output member 20 to the driven element. At this time, the rotation speed of the output member 20 is decelerated compared to the rotation speed of the input member 12.

[0022] In this embodiment, when the crankshaft 24 serving as the input member rotates, the external gear 26 swings due to the eccentric portion 22. When the external gear 26 swings, the meshing position between the external gear 26 and the internal gear 28 changes in the circumferential direction. Along with this, the external gear 26 rotates, and its rotation component is transmitted to the output member 20 via the pin 44.

[0023] Referring to FIG. 2. The speed reducer 10 of this embodiment includes a seal body 38 disposed between the case 16 and the inner member 18. The seal body 38 is for sealing a sealed space 34 including the internal space 32 of the speed reducer 10 on one axial side with respect to the seal body 38. The seal body 38 is disposed between the outer space 48 and the sealed space 34 on the side opposite to the internal space 32 with respect to the seal body 38 in the axial direction, and separates them. The seal body 38 of this embodiment is disposed only between the case 16 and the first inner member 18A (see also FIG. 1). Hereinafter, the side with the internal space 32 in the axial direction with respect to the seal body 38 is referred to as the internal space side S1, and the side opposite to it in the axial direction is referred to as the anti-internal space side S2.

[0024] One of the case 16 and the inner member 18 is referred to as the first member 50, and the other of them is referred to as the second member 52. In this embodiment, an example is described in which the inner member 18 is the first member 50 and the case 16 is the second member 52. The first member 50 is provided with a main sealing surface 68, which will be described later, and the second member 52 is the mounting partner for the main sealing member 54, which will be described later. In addition, the inner member 18 may be the second member 52 and the case 16 may be the first member 50.

[0025] The seal body 38 includes a main seal member 54 attached to the other member 52. The main seal member 54 prevents lubricant leakage from the internal space side S1 to the non-internal space side S2 by sealing the gap between the case 16 and the inner member 18. The main seal member 54 includes a first main body portion 56 attached to the other member 52 and a main lip portion 58 provided on the first main body portion 56. In addition, the main seal member 54 may optionally include a dust lip portion 60 protruding from the main lip portion 58 and a spring member 62 such as a garter spring that presses the main lip portion 58 toward the one member 50. The main seal member 54 in this embodiment includes a first metal ring 64 and a first elastic material 66 integrated with the first metal ring 64 by vulcanization bonding or the like. The first elastic material 66 is made of rubber or the like. In addition, the main seal member 54 may be made of only either the first metal ring 64 or the first elastic material 66.

[0026] The first main body portion 56 includes a first mounting portion 56a that is attached to the circumferential surface of the other member 52 by interference fit or the like, and a first radially extending portion 56b that extends radially from the axial end of the first mounting portion 56a on the side S2 opposite to the internal space. In this embodiment, the first main body portion 56 is composed of both the first metal ring 64 and the first elastic material 66, but it may be composed of either one of them.

[0027] The main lip portion 58 extends from the radial end of the first radially extending portion 56b on the side of the one member 50 to the internal space side S1. The main lip portion 58 is made of the first elastic material 66. The main lip portion 58 contacts the main sealing surface 68 provided on the one member 50. As a result, the main lip portion 58 seals the space between the main lip portion 58 and the main sealing surface 68, preventing the leakage of lubricant from the internal space side S1 to the opposite internal space side S2 through the space between them. In order to satisfy the condition that the main sealing surface 68 is provided on the one member 50, it may be made of a part of the one member 50 or it may be made of another member attached to the one member 50. In this embodiment, the main sealing surface 68 is made of the circumferential surface (here, the outer circumferential surface) of the one member 50 itself, as in the former case.

[0028] The main lip portion 58 includes a lip end portion 58a that protrudes toward the main seal surface 68 and contacts the main seal surface 68, an outer inclined surface 58b that extends from the lip end portion 58a toward the side opposite the internal space S2, and an inner inclined surface 58c that extends from the lip end portion 58a toward the side opposite the internal space S1. In this embodiment, the lip end portion 58a is pointed and protrudes toward the main seal surface 68. The outer inclined surface 58b and the inner inclined surface 58c are inclined so that they move away from the main seal surface 68 as they move away from the lip end portion 58a in the axial direction.

[0029] The dust lip portion 60 is located on the side S2 opposite to the contact point of the main lip portion 58 with the main sealing surface 68, and is in contact with the main sealing surface 68. The dust lip portion 60 blocks dust that would otherwise flow from the outer space 48 towards the main lip portion 58, thereby preventing dust from entering the space between the main lip portion 58 and the main sealing surface 68.

[0030] Refer to Figures 2 and 3. The seal body 38 includes a plurality of threaded portions 72 provided on the main lip portion 58. The plurality of threaded portions 72 are provided on the outer inclined surface 58b of the main lip portion 58. The plurality of threaded portions 72 extend spirally from the lip end portion 58a toward the side opposite the internal space S2. In this embodiment, the threaded portions 72 are composed of grooves that are concavely recessed on the outer inclined surface 58b. Alternatively, the threaded portions 72 may be composed of ribs that protrude convexly on the outer inclined surface 58b. In Figure 2, reference numerals indicate the axial range of the plurality of threaded portions 72.

[0031] The multiple threaded portions 72 constitute threaded regions 74A and 74B, each consisting of multiple threaded portions 72 that are parallel to one another. The threaded regions 74A and 74B constitute a portion of the circumferential range on the outer inclined surface 58b. The threaded regions 74A and 74B include a forward-rotating threaded region 74A, where multiple threaded portions 72 are formed that extend in one circumferential direction (hereinafter referred to as the forward rotation direction) as the axial direction toward the lip end 58a, and a reverse-rotating threaded region 74B, where multiple threaded portions 72 are formed that extend in the other circumferential direction (hereinafter referred to as the reverse rotation direction) as the axial direction toward the lip end 58a. The direction of the helix of the multiple threaded portions 72 is opposite in the forward-rotating threaded region 74A and the reverse-rotating threaded region 74B.

[0032] The multiple threaded portions 72 perform a fluid supply function by pumping when the case 16 and the inner member 18 rotate relative to each other, sending fluid to the internal space side S1 at the point of contact of the main lip portion 58 with the main seal surface 68. For example, when the inner member 18 rotates relative to the case 16 in the forward rotation direction, the pumping action sends fluid to the internal space side S1 through the multiple threaded portions 72 in the forward rotation threaded region 74A. Also, when the inner member 18 rotates relative to the case 16 in the reverse rotation direction, the pumping action sends fluid to the internal space side S1 through the multiple threaded portions 72 in the reverse rotation threaded region 74B. In this case, if the threaded portion 72 is composed of rib portions, the fluid between the multiple threaded portions 72 in each threaded region 74A and 74B is sent to the internal space side S1. Also, if the threaded portion 72 is composed of groove portions, the fluid within the threaded portions 72 in each threaded region 74A and 74B is sent to the internal space side S1.

[0033] In this embodiment, the multiple screw portions 72 constitute a forward-rotating screw region 74A and a reverse-rotating screw region 74B, so that the fluid feeding function can be performed regardless of the relative rotation direction of the inner member 18 with respect to the case 16. If the rotation direction of the inner member 18 with respect to the case 16 is determined, then that rotation direction can be considered the forward rotation direction, and the multiple screw portions 72 may constitute only the forward-rotating screw region 74A, without having to constitute the reverse-rotating screw region 74B.

[0034] In this way, the multiple screw portions 72 exert a fluid supply function when the case 16 and the inner member 18 rotate relative to each other, thereby increasing the amount of fluid supplied to the internal space side S1. This fluid supply function is a pumping force that acts due to the uneven distribution of pressure between the lip end 58a of the main lip portion 58 and the main seal surface 68, and is exerted separately from the pumping force that supplies fluid to the internal space side S1.

[0035] Refer to Figure 2. The seal body 38 is equipped with a capture portion 76 capable of capturing foreign matter that is about to flow from the internal space 32 to the main lip portion 58. The capture portion 76 is provided separately from the main bearing 42 and other bearings. In this embodiment, the capture portion 76 is composed of an auxiliary seal member 78 that can capture foreign matter by blocking it from flowing from the internal space 32 to the main lip portion 58 along with the lubricant. The capture portion 76 is composed of an annular body that is continuous in an annular shape, similar to the auxiliary seal member 78.

[0036] A gap space 80 is formed between the main sealing member 54 and the auxiliary sealing member 78. The gap space 80 is formed at a position sandwiched between at least the main sealing member 54 and the auxiliary sealing member 78. In this embodiment, the gap space 80 is at least surrounded by the main sealing member 54, the auxiliary sealing member 78 and the inner member 18. A portion of the gap space 80 is provided on the radially opposite side of the main sealing surface 68 to the main lip portion 58 of the main sealing member 54.

[0037] The auxiliary sealing member 78 comprises a second main body portion 82 and an auxiliary lip portion 84 provided on the second main body portion 82. The auxiliary sealing member 78 also comprises a second metal ring 86 and a second elastic material 88 integrated with the second metal ring 86 by vulcanization bonding or the like. The second elastic material 88 is made of rubber or the like. In addition, the auxiliary sealing member 78 may be composed of only either the second metal ring 86 or the second elastic material 88.

[0038] In this embodiment, the second main body portion 82 is attached to the first main body portion 56. Alternatively, the second main body portion 82 may be attached to the inner circumference of the case 16 or to the outer circumference of the inner member 18. The second main body portion 82 includes a second mounting portion 82a that is attached to a mating part by interlocking or the like, and a second radially extending portion 82b that extends radially from the second mounting portion 82a. In this embodiment, the second main body portion 82 is composed of a second metal ring 86 and a second elastic material 88, but it may be composed of either one of them. Furthermore, in this embodiment, the second main body portion 82 is composed of the second elastic material 88 only at the end of the second radially extending portion 82b.

[0039] The auxiliary lip portion 84 contacts an auxiliary sealing surface 90 provided on either the case 16 or the inner member 18. As a result, the auxiliary sealing member 78 isolates the gap space 80 from the internal space 32. The gap space 80 is sealed by at least the main sealing member 54 and the auxiliary sealing member 78. In this embodiment, the auxiliary sealing surface 90 is provided on the inner member 18. To satisfy the condition that the auxiliary sealing surface 90 is provided on either the case 16 or the inner member 18, it may be composed of a part of either the case 16 or the inner member 18, or of a separate member attached to either of them. In this embodiment, the auxiliary sealing surface 90 is composed of the circumferential surface of the inner member 18 itself, as in the former case. Furthermore, while this embodiment describes an example where the auxiliary sealing surface 90 is the same surface as the main sealing surface 68 and continuous without any steps, it may be provided on a different surface or a different member than the main sealing surface 68. Furthermore, if the second main body portion 82 is attached to the inner member 18 in place of the first main body portion 56, the auxiliary sealing surface 90 only needs to be provided on the case 16.

[0040] The auxiliary lip portion 84 extends toward the auxiliary seal surface 90 from the radial end of the second radially extending portion 82b on the auxiliary seal surface 90 side. The auxiliary lip portion 84 is made of a second elastic material 88. The auxiliary lip portion 84 in this embodiment includes a base end portion 84a that extends radially toward the auxiliary seal surface 90 from the second radially extending portion 82b, and a tip end portion 84b that extends toward the internal space S1 than the base end portion 84a and contacts the auxiliary seal surface 90. A recess 92 is formed between the second main body portion 82 and the auxiliary lip portion 84, recessed toward the side opposite the internal space S2.

[0041] The effects of the reduction gear 10 described above will now be explained.

[0042] Each of the multiple threaded portions 72 is composed of a groove or a rib. When the threaded portion 72 is a groove at the point where the main lip portion 58 contacts the main seal surface 68, the main lip portion 58 becomes less likely to contact the main seal surface 68 at that point. Also, when the threaded portion 72 is a rib, the main lip portion 58 becomes less likely to contact the main seal surface 68 between the multiple threaded portions 72. As a result, when the main lip portion 58 is provided with multiple threaded portions 72, the contact area at the point where the main lip portion 58 contacts the main seal surface 68 tends to become smaller, resulting in higher surface pressure. Consequently, when the main lip portion 58 is provided with multiple threaded portions 72, as described above, there is a problem that the contact state of the main lip portion 58 with the main seal surface 68 tends to become unstable due to the influence of foreign matter that gets caught in the internal space 32. This means that the problem described here is more likely to occur compared to when the main lip portion 58 is not provided with multiple threaded portions 72.

[0043] The reduction gear 10 in this embodiment is equipped with a capture unit 76 that captures foreign matter that is about to flow from the internal space 32 to the main lip portion 58. Therefore, even if foreign matter such as wear particles is generated in the internal space 32 of the reduction gear, the amount of foreign matter that reaches the main lip portion 58 from the internal space 32 can be reduced by capturing the foreign matter with the capture unit 76. This is advantageous in suppressing the jamming of foreign matter in the main lip portion 58, which is provided with multiple screw portions 72. Furthermore, by reducing the amount of foreign matter that reaches the main lip portion 58 from the internal space 32, it is advantageous in maintaining the sealing performance of the main lip portion 58 of the seal body 38 over a long period of time.

[0044] The auxiliary sealing member 78 constituting the capture section 76 isolates the gap space 80 from the internal space 32. Therefore, by blocking the flow of foreign matter from the internal space 32 to the gap space 80 with the auxiliary sealing member 78, the amount of foreign matter reaching the main lip section 58 from the internal space 32 can be further reduced. In addition, by supplying fluid to this gap space 80 through the multiple screw sections 72 of the main lip section 58, the pressure in the gap space 80 can be made higher than that in the internal space 32 of the gearbox. This makes it difficult for foreign matter to flow from the low-pressure internal space 32 to the high-pressure gap space 80, and the amount of foreign matter reaching the main lip section 58 via the gap space 80 can be reduced. This, in turn, is even more advantageous in suppressing the jamming of foreign matter in the main lip section 58.

[0045] Next, other features of the speed reducer 10 will be explained. We will consider the interference fit A (mm) of the main lip portion 58 with respect to the main sealing surface 68 and the interference fit B (mm) of the auxiliary lip portion 84 with respect to the auxiliary sealing surface 90. The state in which the seal body 38 is not incorporated into the speed reducer 10 and the lip portions 58 and 84 of the seal body 38 are not deformed by contact with other members is called the undeformed state. The state in which the seal body 38 is incorporated into the speed reducer 10 and the lip portions 58 and 84 of the seal body 38 are deformed by contact with other members (sealing surfaces) is called the deformed state. The interference fits A and B represent the amount of radial deformation of each lip portion 58 and 84 when it changes from the undeformed state to the deformed state. These interference fits A and B can be derived using the difference between the diameter of each lip portion 58 and 84 in the undeformed state and the diameter of the sealing surfaces 68 and 90 with which the lip portions 58 and 84 contact.

[0046] For example, consider the case where one member 50 becomes the inner member 18, and the main sealing surface 68 and auxiliary sealing surface 90 constitute the outer circumferential surface of the inner member 18, etc. In this case, the interference fit A means the difference between the outer diameter R68 of the main sealing surface 68 (see Figure 1) and the minimum inner diameter R58 of the main lip portion 58 when it is in an undeformed state. Also, in this case, the interference fit B means the difference between the outer diameter R90 of the auxiliary sealing surface 90 and the minimum inner diameter R84 of the auxiliary lip portion 84 when it is in an undeformed state. In this case, it is assumed that the outer diameter R68 of the main sealing surface 68 > the minimum inner diameter R58 of the main lip portion 58, and the outer diameter R90 of the auxiliary sealing surface 90 > the minimum inner diameter R84 of the auxiliary lip portion 84. In this embodiment, when it is in an undeformed state, the minimum inner diameter R58 of the main lip portion 58 is smaller than the minimum inner diameter R84 of the auxiliary lip portion 84. Furthermore, in this embodiment, the outer diameter R68 of the main sealing surface 68 and the outer diameter R90 of the auxiliary sealing surface 90 are the same.

[0047] On the other hand, consider the case where member 50 becomes case 16, and the main sealing surface 68 and auxiliary sealing surface 90 constitute the inner circumferential surface of case 16, etc. In this case, the overlap A means the difference between the inner diameter of the main sealing surface 68 and the maximum outer diameter of the main lip portion 58. Also, the overlap B means the difference between the inner diameter of the auxiliary sealing surface 90 and the maximum outer diameter of the auxiliary lip portion 84. In this case, it is assumed that the inner diameter of the main sealing surface 68 < the maximum outer diameter of the main lip portion 58, and the inner diameter of the auxiliary sealing surface 90 < the maximum outer diameter of the auxiliary lip portion 84.

[0048] In this embodiment, the overlap A of the main lip portion 58 is greater than the overlap B of the auxiliary lip portion 84. This increases the surface pressure of the main lip portion 58 against the main sealing surface 68, compared to the case where the overlap A of the main lip portion 58 is the same as the overlap B of the auxiliary lip portion 84, thereby improving the sealing performance of the main lip portion 58. Furthermore, compared to the case where the overlap B of the auxiliary lip portion 84 is the same as the overlap A of the main lip portion 58, the surface pressure of the auxiliary lip portion 84 against the auxiliary sealing surface 90 is reduced, thereby reducing friction loss due to contact between the auxiliary sealing surface 90 and the auxiliary lip portion 84.

[0049] Furthermore, in order to increase the surface pressure of the main lip portion 58 while lowering the surface pressure of the auxiliary lip portion 84, the rigidity of the main lip portion 58 may be made higher than that of the auxiliary lip portion 84. In order to increase the rigidity of the main lip portion 58, the radial dimension of its base end portion may be made thicker. Also, in order to lower the rigidity of the auxiliary lip portion 84, the axial dimension of its base end portion 84a may be made smaller.

[0050] At least a part of the tip-side portion 84b of the auxiliary lip portion 84 is provided so as to extend toward the tip side and axially toward the inner space 32. As a result, as the pressure in the clearance space 80 increases with respect to the pressure in the inner space 32, the auxiliary lip portion 84 is more likely to deform so as to be displaced toward the inner space side S1. Due to such deformation of the auxiliary lip portion 84, a gap that communicates the clearance space 80 and the inner space 32 temporarily occurs between the auxiliary lip portion 84 and the auxiliary seal surface 90, and the pressure in the clearance space 80 can be released to the inner space 32 side through the gap. Such deformation of the auxiliary lip portion 84 occurs when the pressure difference ΔP (= P1 - P2) between the pressure P1 in the clearance space 80 and the pressure P2 (<P1) in the inner space 32 becomes at least a predetermined pressure or more. The units of each pressure P1 and P2 are Pa.

[0051] When such a pressure becomes a predetermined pressure or more, in order to cause such deformation of the auxiliary lip portion 84, the rigidity of the auxiliary lip portion 84, the tightening margin B of the auxiliary lip portion 84, the length of the contact portion of the auxiliary lip portion 84 with respect to the auxiliary seal surface 90, etc. may be adjusted. The higher the rigidity of the auxiliary lip portion 84, the larger the tightening margin B, and the longer the length of the contact portion of the auxiliary lip portion 84 with respect to the auxiliary seal surface 90, the more difficult it is for the auxiliary lip portion to deform, and the larger the pressure difference ΔP at which the deformation of the auxiliary lip portion 84 occurs can be made. In order to increase the rigidity of the auxiliary lip portion 84, for example, the axial dimension of the base-end side portion 84a of the auxiliary lip portion 84 may be increased. It can also be said that the auxiliary lip portion 84 is configured to be able to release the pressure in the clearance space 80 to the inner space 32 side when the pressure difference ΔP becomes at least a predetermined pressure or more as described above.

[0052] In addition, in order to reduce the pressure difference ΔP at which the deformation of the auxiliary lip portion 84 occurs, any one of the following (1), (2), and (3) may be satisfied. The length of the contact portion in (2) is, for example, the axial length of the contact portion being referred to. As a result, compared with the case where none of these conditions is satisfied, when the pressure becomes a predetermined pressure or more, the auxiliary lip portion 84 is more likely to deform, and the pressure in the clearance space 80 can be reliably released to the inner space 32 side. (1) Young's modulus of the main lip portion 58 (N / mm 2 To make the Young's modulus of the auxiliary lip portion 84 lower than ) (2) The length of the contact area (mm) of the auxiliary lip portion 84 with respect to the auxiliary seal surface 90 is made smaller than the length (mm) of the contact area (mm) of the main lip portion 58 with respect to the main seal surface 68. (3) The tightening allowance A of the main lip portion 58 shall be greater than the tightening allowance B of the auxiliary lip portion 84.

[0053] In this embodiment, fluid is supplied to the gap space 80 by the multiple threaded portions 72 of the main lip portion 58, thereby increasing the pressure in the gap space 80. However, if the pressure P1 in the gap space 80 increases excessively, the surface pressure of the main lip portion 58 will increase excessively in accordance with the pressure P1 in the gap space 80, which can lead to adverse effects such as excessive friction loss. In this regard, the auxiliary lip portion 84 in this embodiment is configured to release the pressure in the gap space 80 to the internal space 32 when the pressure difference ΔP between the pressure P1 in the gap space 80 and the pressure P2 in the internal space 32 increases to a predetermined pressure or more. This suppresses an excessive increase in the pressure P1 in the gap space 80 and prevents the occurrence of adverse effects caused by it.

[0054] Lubricant may be sealed in the gap space 80. The lubricant sealed in this gap space 80 (hereinafter referred to as the gap space lubricant) and the lubricant sealed in the internal space 32 (hereinafter referred to as the internal space lubricant) may be the same or different. For example, when grease is used as the lubricant, the consistency of the gap space lubricant may be higher than that of the internal space lubricant. Also, when lubricating oil is used as the lubricant, the viscosity of the gap space lubricant may be higher than that of the internal space lubricant. This makes it easier for the lubricant to remain in the gap space 80, which is advantageous in suppressing leakage of lubricant into the outer space 48.

[0055] (Second Embodiment) Refer to Figures 4 and 5. In the following embodiments, the same content as in the first embodiment may apply to components described in the first embodiment but not described below.

[0056] The gearbox 10 of this embodiment differs in the configuration of the auxiliary lip portion 84 of the seal body 38. In the first embodiment, an example was described in which the interference fit B of the auxiliary lip portion 84 with respect to the auxiliary seal surface 90 was smaller than the interference fit A of the main lip portion 58 with respect to the main seal surface 68. In contrast, in this embodiment, the interference fit B of the auxiliary lip portion 84 with respect to the auxiliary seal surface 90 is larger than the interference fit A of the main lip portion 58 with respect to the main seal surface 68. To achieve this, in this embodiment, when in an undeformed state, the minimum inner diameter R84 of the auxiliary lip portion 84 is smaller than the minimum inner diameter R58 of the main lip portion 58. Also, in this embodiment, the outer diameter R68 of the main seal surface 68 and the outer diameter R90 of the auxiliary seal surface 90 are the same. As a result, compared to the case where the interference fit B of the auxiliary lip portion 84 is the same as the interference fit A of the main lip portion 58, the surface pressure of the auxiliary lip portion 84 with respect to the auxiliary seal surface 90 can be increased, and the sealing performance by the auxiliary lip portion 84 can be improved.

[0057] In the first embodiment, an example was described in which the auxiliary lip portion 84 is located in a position opposite to the internal space S2 than the position 82c on the innermost side S1 of the second radially extending portion 82b. In contrast, the auxiliary lip portion 84 in this embodiment extends to the inner space S1 beyond the position 82c on the innermost side S1 of the second radially extending portion 82b. This increases the contact area of ​​the auxiliary lip portion 84 with the auxiliary sealing surface 90, thereby improving the sealing performance of the auxiliary lip portion 84.

[0058] In addition, the gearbox 10 of this embodiment can achieve the same effects as the first embodiment, within a range that is not inconsistent with the first embodiment.

[0059] Next, we will describe the transformation forms of each component described so far.

[0060] The capture portion 76 may be capable of attracting foreign objects made of soft magnetic material by magnetic force. The specific means for achieving this are not particularly limited. For example, magnetic powder made of magnetized ferromagnetic material may be mixed into the second elastic material 88 of the capture portion 76. Alternatively, the second metal ring 86 of the capture portion 76 may be made of magnetized ferromagnetic material. In addition, a magnetized ferromagnetic material such as a permanent magnet may be incorporated into a part of the capture portion 76. In any case, it is sufficient that a ferromagnetic material capable of attracting foreign objects by magnetic force is provided in at least a part of the capture portion 76. This allows foreign objects made of soft magnetic material to be attracted by the capture portion 76, and the amount of foreign object reaching the main lip portion 58 from the internal space 32 can be reduced. This is advantageous in suppressing foreign object jamming at the main lip portion 58.

[0061] The reduction mechanism 14 is not particularly limited in its specific type, as long as it has an external gear 26 and an internal gear 28 that mesh with each other. For example, in addition to the eccentric oscillating reduction mechanism, a flexible meshing reduction mechanism (including cylindrical, top hat, and cup types), a simple planetary mechanism, etc., may be used as the reduction mechanism 14. When an eccentric oscillating reduction mechanism is used as the reduction mechanism 14, its specific type is not particularly limited. In this embodiment, a center crank type in which the crankshaft 24 is provided on the rotational centerline C20 of the output member 20 has been described. Alternatively, a distribution type in which the crankshaft 24 is provided at a position radially offset from the rotational centerline C20 of the output member 20 may be used. When an eccentric oscillating reduction mechanism is used as the reduction mechanism 14, the internal gear 28 may be oscillated instead of the external gear 26. In this case, the oscillation of the internal gear 28 rotates the external gear 26, and the rotation of the external gear 26 is transmitted to the inner member 18, which acts as the output member 20, and the rotation is output from the inner member 18. In this case, the inner member 18 rotates together with the external gear 26, thereby synchronizing with the rotation of the external gear 26. Thus, the inner member 18 is not limited to a carrier that synchronizes with the rotation component of the external gear 26 by a pin or the like, but may also synchronize with the rotation component of the external gear 26 by rotating together with the external gear 26, or it may be composed of the external gear 26 itself.

[0062] In the case of eccentric oscillation type reduction gears and flexible mesh type reduction gears, the lubricant in the internal space 32 tends to flow along with foreign matter due to the rotation of the vibrating body or the rotation of the crankshaft, and foreign matter tends to reach the space between the main lip portion 58 and the main seal surface 68. Applying the seal body 38 of this embodiment is effective in that it can suppress the jamming of foreign matter at the main lip portion 58 even in such cases.

[0063] The placement position of the seal 38 is not particularly limited. For example, it may be placed between the input member 12 and the inner member 18, in addition to between the case 16 and the inner member 18. It may also be placed between the case 16 and the second inner member 18B, in addition to between the case 16 and the first inner member 18A. Alternatively, it may be placed only between the case 16 and the second inner member 18B. Furthermore, the seal 38 of this disclosure may be placed between one of the first inner member 18A and the second inner member 18B and the case 16, and another seal member may be placed between the other and the case 16.

[0064] The auxiliary sealing member 78 constituting the capture portion 76 does not necessarily have an auxiliary lip portion 84 that contacts the auxiliary sealing surface 90. In this case, the gap space 80 and the internal space 32 may be in communication. In addition, the capture portion 76 may not have a function to block foreign matter like the auxiliary sealing member 78, but may capture foreign matter that is trying to flow from the internal space 32 to the main lip portion 58 by attracting foreign matter with magnetic force as described above.

[0065] In order to isolate the gap space 80 from the internal space 32, the second main body portion 82 of the auxiliary sealing member 78 may be attached to the case 16. In this case as well, the auxiliary lip portion 84 of the auxiliary sealing member 78 only needs to be in contact with the auxiliary sealing surface 90 provided on the inner member 18. Alternatively, the second main body portion 82 of the auxiliary sealing member 78 may be attached to the inner member 18. In this case, the auxiliary lip portion 84 of the auxiliary sealing member 78 only needs to be in contact with the auxiliary sealing surface 90 provided on the case 16.

[0066] The tightening allowance A of the main lip portion 58 and the tightening allowance B of the auxiliary lip portion 84 are not particularly limited. These tightening allowances A and B may be the same. The auxiliary lip portion 84 does not need to be configured to release the pressure in the gap space 80 to the internal space 32 when the pressure difference ΔP between the pressure P1 in the gap space 80 and the pressure P2 in the internal space 32 exceeds a predetermined pressure.

[0067] The contents of each component described in the embodiments above are illustrative. The abstract technical ideas derived from these should not be interpreted restrictively to the contents of this specification. Many design changes, such as modifications, additions, and deletions, are possible for the contents of each component described in the embodiments. Such modifications are emphasized by the notation "this form" and "embodiment." However, design changes are also permitted for contents without such notation. Any combination of the above components is also valid. For example, any explanatory items from other embodiments may be combined with an embodiment, and any explanatory items from an embodiment and other modified forms may be combined with a modified form. The hatching applied to the cross-section in the drawings does not limit the material of the object to which the hatching is applied. The structures and numerical values ​​mentioned in the embodiments and modified forms naturally include those that can be considered identical when considering manufacturing tolerances, etc. Components composed of a single member in the description in this specification may be composed of multiple members. Similarly, components composed of multiple members may be composed of a single member. [Explanation of Symbols]

[0068] 10...Reduction gear, 14...Reduction mechanism, 16...Case, 18...Inner member, 20...Output member, 26...External gear, 28...Internal gear, 32...Internal space, 38...Seal body, 50...One-sided member, 54...Main seal member, 58...Main lip portion, 68...Main seal surface, 72...Screw portion, 76...Capture portion, 78...Auxiliary seal member, 80...Gap space, 84...Auxiliary lip portion, 90...Auxiliary seal surface.

Claims

1. A reduction mechanism having external gears and internal gears that mesh with each other, A case having an internal space on the inside that accommodates at least a part of the reduction mechanism, An inner member positioned inside the case, The case and the inner member are disposed between them, The case and the inner member are both output members that output rotation, in this reduction gear. The sealing body is A main lip portion that contacts the main sealing surface provided on one of the case and the inner member, The main lip portion is provided with a plurality of screw portions that increase the amount of fluid supplied to the internal space in the axial direction when the case and the inner member rotate relative to each other, A reduction gear comprising a capturing unit capable of capturing foreign matter that is about to flow from the internal space toward the main lip portion.

2. The sealing body comprises a main sealing member having the main lip portion and an auxiliary sealing member constituting the capture portion. A gap is formed between the main sealing member and the auxiliary sealing member. The reduction gear according to claim 1, wherein the auxiliary sealing member isolates the gap space from the internal space.

3. The auxiliary sealing member comprises an auxiliary lip portion that contacts an auxiliary sealing surface provided on either the inner member or the case, The gearbox according to claim 2, wherein the interference fit of the main lip portion with respect to the main sealing surface is greater than the interference fit of the auxiliary lip portion with respect to the auxiliary sealing surface.

4. The auxiliary sealing member comprises an auxiliary lip portion that contacts an auxiliary sealing surface provided on either the inner member or the case, The gearbox according to claim 2, wherein the auxiliary lip portion is configured to release the pressure in the gap space to the internal space when the pressure difference ΔP between the pressure P1 in the gap space and the pressure P2 (<P1) in the internal space exceeds a predetermined pressure.

5. The reduction gear according to claim 1, wherein the capturing unit is capable of attracting foreign objects by magnetic force.

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