speed reducer

Abstract

A speed reducer that is advantageous in inhibiting the intrusion of foreign matter in a main lip portion provided with a plurality of thread portions. A speed reducer that includes a speed reduction mechanism having an external gear and an internal gear that mesh with each other; a housing (16) provided with an internal space (32) that accommodates at least a portion of the speed reduction mechanism on the inside; an inside member (18) disposed on the inside of the housing (16); and a seal body (38) disposed between the housing (16) and the inside member (18), one of the housing (16) and the inside member (18) being an output member that rotates to output, the seal body (38) including a main lip portion (58) that contacts a main seal surface (68) provided to one of the housing (16) and the inside member (18) that is the one member; a plurality of thread portions (72) provided on the main lip portion (58) and that increase the amount of fluid fed to the inside of the internal space in the axial direction when the housing (16) and the inside member (18) rotate relative to each other; and a capturing portion (76) that can capture foreign matter that attempts to flow from the internal space (32) to the side of the main lip portion (58).

Description

[0001] This application claims priority to Japanese Patent Application No. 2024-226797, filed on December 23, 2024. The entire contents of that Japanese application are incorporated herein by reference. Technical Field

[0002] This disclosure relates to a speed reducer. Background Technology

[0003] Patent Document 1 discloses a speed reducer comprising: a speed reduction mechanism having an external gear and an internal gear meshing with each other; a housing having an internal space on its inner side that accommodates at least a portion of the speed reduction mechanism; an inner component disposed on the inner side of the housing; and a sealing body disposed between the housing and the inner component. The sealing body of Patent Document 1 comprises: a main lip that contacts a main sealing surface disposed on the housing; and a plurality of threaded portions disposed on the main lip, which, when the housing and the inner component rotate relative to each other, increase the amount of fluid fed axially into the internal space.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2024-48708

[0005] A comparison was made between cases where multiple threads were provided on the main lip and cases where multiple threads were not provided on the main lip. In the former case, compared to the latter case, the contact area between the main lip and the main sealing surface tends to have higher surface pressure due to the smaller contact area. Furthermore, there is a unique situation where wear dust, as foreign matter, is easily generated in the internal space of the reducer due to the meshing of the components of the reduction mechanism.

[0006] The case of foreign objects generated within the internal space of the reducer entering and becoming lodged between the main lip, which has multiple threaded portions, and the main sealing surface was investigated. In this situation, the main lip tends to maintain a high surface pressure due to the foreign object's lodging, and it is prone to wear due to the pressure from the foreign object. As a result, the contact state between the main lip and the main sealing surface easily becomes unstable due to these effects, increasing the risk of lubricant leakage. In other words, the following problem exists: when the main lip has multiple threaded portions, the contact state between the main lip and the main sealing surface easily becomes unstable due to the influence of foreign objects generated within the internal space. Summary of the Invention

[0007] One of the purposes of this disclosure is to provide a speed reducer that facilitates the suppression of foreign objects from being bitten into a main lip provided with multiple threaded portions.

[0008] The speed reducer disclosed herein comprises: a speed reduction mechanism having an external gear and an internal gear meshing with each other; a housing having an internal space on its inner side accommodating at least a portion of the speed reduction mechanism; an inner component disposed on the inner side of the housing; and a sealing body disposed between the housing and the inner component, wherein one of the housing and the inner component serves as an output component for output rotation, and the sealing body comprises:

[0009] The main lip contacts the main sealing surface of one of the components that forms one of the housing and the inner component;

[0010] Multiple threaded portions are provided on the main lip, and when the housing rotates relative to the inner component, the axial flow of fluid into the internal space increases; and

[0011] The capturing unit is capable of capturing foreign objects that wish to flow from the internal space to the main lip side.

[0012] Invention Effects

[0013] According to this disclosure, a speed reducer can be provided that is advantageous in suppressing the biting of foreign objects in a main lip provided with multiple threaded portions. Attached Figure Description

[0014] Figure 1 This is a side sectional view showing the speed reducer of the first embodiment.

[0015] Figure 2 yes Figure 1 Enlarged view of the area around the seal.

[0016] Figure 3 This is a side sectional view showing the sealing body of the first embodiment.

[0017] Figure 4 From and Figure 2 The diagram shows the speed reducer of the second embodiment viewed from the same viewpoint.

[0018] Figure 5 This is a side sectional view showing the sealing body of the second embodiment.

[0019] In the diagram: 10-reducer, 14-reduction mechanism, 16-housing, 18-inner component, 20-output component, 26-external gear, 28-internal gear, 32-internal space, 38-sealing body, 50-one component, 54-main sealing component, 58-main lip, 68-main sealing surface, 72-threaded part, 76-catching part, 78-auxiliary sealing component, 80-gap space, 84-auxiliary lip, 90-auxiliary sealing surface. Detailed Implementation

[0020] The following describes embodiments of the speed reducer used to implement this disclosure. Identical or equivalent elements are labeled with the same reference numerals, and repeated descriptions are omitted. In the figures, for ease of explanation, constituent elements are appropriately omitted, enlarged, or reduced. The figures are viewed according to the direction of the symbols.

[0021] (First Embodiment) Reference Figure 1 In this specification, the direction along the rotation center line C20 of the output component 20 of the reducer 10 is referred to as the axial direction, and the radial direction and the circumferential direction with the rotation center line C20 as the center are referred to as the radial and circumferential directions, respectively.

[0022] The speed reducer 10 is assembled in the main machine. The main machine is, for example, at least a 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) handling equipment such as conveyors, and (4) vehicles. The speed reducer 10 reduces the rotation input from the prime mover and outputs the rotation, thereby driving the driven parts that are part of the main machine. The prime mover is, for example, a motor or engine.

[0023] The speed reducer 10 includes: an input member 12 for inputting rotational speed output from a prime mover; a speed reduction mechanism 14 for reducing the rotational speed of the input member 12; a housing 16 for housing at least a portion of the speed reduction mechanism 14; and an inner member 18 disposed inside the housing 16. In this embodiment, the inner member 18 serves as an output member 20 that outputs the rotational speed transmitted from the speed reduction mechanism 14 to the driven member. Alternatively, the housing 16 may also serve as the output member 20.

[0024] The rotation of the prime mover can be input to the input unit 12 via other power transmission components of the reducer 10, or it can be input directly. In this embodiment, the reducer 10 uses a center crankshaft type eccentric oscillating type reducer mechanism as the reducer mechanism 14. The reducer 10 using this center crankshaft type eccentric oscillating type reducer mechanism includes a crankshaft 24 having an eccentric portion 22, which serves as the input unit 12. The crankshaft 24 has at least one (here, three) eccentric portions 22. The eccentric portions 22 have a circular shape that is eccentric relative to the rotation center line of the crankshaft 24.

[0025] 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 correspondingly provided with the eccentric portion 22 and is supported on the corresponding eccentric portion 22 via an eccentric bearing 30. In this embodiment, the external gear 26 can swing through the corresponding eccentric portion 22. In this embodiment, the internal gear 28 is provided on the inner periphery of the housing 16. In this embodiment, the internal gear 28 has a gear body 28a that also serves as the housing 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 supported by the gear body 28a and is rotatable. Alternatively, the internal tooth portion 28b may be composed of the same component as the gear body 28a. Alternatively, depending on the type of reduction mechanism 14, the internal gear 28 may be separately provided from the housing 16.

[0026] An internal space 32 is provided inside the housing 16. At least a portion of the reduction mechanism 14 is accommodated in the internal space 32. In this embodiment, the internal space 32 accommodates the external gear 26 of the reduction mechanism 14. When the housing 16 and the internal gear 28 are separate components, the internal space 32 can accommodate both the external gear 26 and the internal gear 28 of the reduction mechanism 14.

[0027] The internal space 32 is at least a part of a sealed space 34 containing lubricants such as lubricating oil and grease. The lubricant is used to lubricate the reduction gear 14, which is at least housed in the internal space 32. In this embodiment, the sealed space 34 is also formed inside the motor coupling 36 that connects the motor (not shown) which serves as the prime mover to the housing 16. Thus, the sealed space 34 is continuous with the interior of other components connected to the reduction gear 10, in addition to the internal space 32. The other components forming the sealed space 34 are not particularly limited. Furthermore, the sealed space 34 may also consist solely of the internal space 32.

[0028] The sealed space 34 is sealed by at least the sealing body 38. The sealed space 34 can be sealed not only by the sealing body 38, but also by other sealing components 40A and 40B. In this embodiment, one sealing component 40A is constituted by a sealing cap or the like that closing the through hole 18a formed in the inner component 18. Furthermore, in this embodiment, other sealing components 40B are also disposed between the housing 16 and the motor coupling 36. In addition, in this embodiment, other sealing components (not shown) are also disposed between the motor shaft (not shown) connected to the input component 12 and the motor coupling 36. The number and type of the sealing body 38 and sealing components 40 that seal the sealed space 34 are not particularly limited, and various types can be applied depending on the type of reducer 10.

[0029] The inner component 18 is capable of rotating relative to the housing 16 during the operation of the reducer 10. A main bearing 42 supporting the output component 20 is disposed between the housing 16 and the inner component 18. In this embodiment, the inner component 18 includes a first inner component 18A disposed on one axial side relative to the reduction mechanism 14 and a second inner component 18B disposed on the other axial side. In this embodiment, the driven component is connected to the first inner component 18A by bolts or the like. The first inner component 18A and the second inner component 18B are connected together by bolts or the like via pins 44.

[0030] In this embodiment, the inner component 18 is formed by a bracket capable of synchronizing with the rotational component of the external gear 26. "Synchronizing with the rotational component" here means maintaining the rotational component of the external gear 26 and the bracket at the same magnitude within a numerical range including zero. A pin 44 protrudes from the bracket and axially penetrates the external gear 26. The pin 44 indirectly contacts the external gear 26 via a roller 46, thereby enabling synchronization of the rotational component of the external gear 26 with the inner component 18. Alternatively, the pin 44 may directly contact the external gear 26.

[0031] The above describes an example of the operation of the reducer 10. If the rotation output from the prime mover is input to the input component 12, the input component 12 rotates. If the input component 12 rotates, the rotation is reduced by the reduction mechanism 14 and transmitted to the output component 20, and then output from the output component 20 to the driven component. At this time, the rotational speed of the output component 20 is lower than the rotational speed of the input component 12.

[0032] In this embodiment, if the crankshaft 24, which serves as the input component, rotates, the external gear 26 oscillates due to its eccentric portion 22. As the external gear 26 oscillates, the meshing position between the external gear 26 and the internal gear 28 changes circumferentially. Subsequently, the external gear 26 rotates, and its rotational component is transmitted to the output component 20 via the pin 44.

[0033] refer to Figure 2 The speed reducer 10 of this embodiment includes a sealing body 38 disposed between the housing 16 and the inner component 18. The sealing body 38 seals a sealing space 34 including the internal space 32 of the speed reducer 10 located axially opposite to the sealing body 38. The sealing body 38 is disposed between the outer space 48, located axially opposite to the internal space 32, and the sealing space 34, thereby separating them. In this embodiment, the sealing body 38 is disposed only between the housing 16 and the first inner component 18A (see reference). Figure 1 Hereinafter, the side with an internal space 32 in the axial direction relative to the sealing body 38 will be referred to as the internal space side S1, and the side opposite to this in the axial direction will be referred to as the anti-internal space side S2.

[0034] One of the housing 16 and the inner component 18 is referred to as component 50, and the other is referred to as component 52. In this embodiment, an example in which the inner component 18 is component 50 and the housing 16 is component 52 will be described. The main sealing surface 68, which will be described later, is provided on component 50, and component 52 becomes the mounting object of the main sealing component 54, which will be described later. Alternatively, the inner component 18 may also be component 52, and the housing 16 may also be component 50.

[0035] The sealing body 38 includes a main sealing member 54 mounted on the other component 52. The main sealing member 54 prevents lubricant from leaking from the internal space side S1 to the reverse internal space side S2 through the gap between the sealed housing 16 and the inner component 18. The main sealing member 54 includes a first main body portion 56 mounted on the other component 52 and a main lip portion 58 provided on the first main body portion 56. Alternatively, as an arbitrary structure, the main sealing member 54 may also include a dustproof lip 60 protruding from the main lip portion 58 and a spring member 62 such as a retaining ring that presses the main lip portion 58 towards one of the components 50. In this embodiment, the main sealing member 54 includes a first metal ring 64 and a first elastic material 66 integrally formed with the first metal ring 64 by means of vulcanization bonding or the like. The first elastic material 66 is made of rubber or the like. Alternatively, the main sealing member 54 may be composed of only either the first metal ring 64 or the first elastic material 66.

[0036] The first main body 56 includes: a first mounting portion 56a, which is mounted to the peripheral portion of another component 52 by an interference fit or the like; and a first radially extending portion 56b, which extends radially from the axial end of the anti-internal space side S2 of the first mounting portion 56a. In this embodiment, the first main body 56 is composed of both a first metal ring 64 and a first elastic material 66, but it may also be composed of either one.

[0037] The main lip 58 extends from the radial end of the first radial extension 56b on the side of one component 50 toward the inner space side S1. The main lip 58 is made of a first elastic material 66. The main lip 58 contacts the main sealing surface 68 provided on the one component 50. Thus, the main lip 58 seals the space between itself and the main sealing surface 68, preventing lubricant from leaking from the inner space side S1 to the anti-inner space side S2 through these spaces. The main sealing surface 68 may be formed by a part of the one component 50 or by other components mounted on the one component 50, to satisfy the condition of being provided on the one component 50. In this embodiment, the main sealing surface 68, as in the former case, is formed by the peripheral surface (here, the outer peripheral surface) of the one component 50 itself.

[0038] The main lip 58 includes a lip end portion 58a that protrudes toward and contacts the main sealing surface 68, an outer inclined surface 58b extending from the lip end portion 58a toward the reverse inner space side S2, and an inner inclined surface 58c extending from the lip end portion 58a toward the inner space side S1. In this embodiment, the lip end portion 58a has a sharp shape protruding toward the main sealing surface 68. The outer inclined surface 58b and the inner inclined surface 58c are inclined in a direction that separates them from the main sealing surface 68 axially away from the lip end portion 58a.

[0039] The dustproof lip 60 is positioned further towards the inner space side S2 than the contact portion of the main lip 58 relative to the main sealing surface 68, and contacts the main sealing surface 68. The dustproof lip 60 prevents dust from entering between the main lip 58 and the main sealing surface 68 by cutting off dust that wants to flow from the outer space 48 to the main lip 58.

[0040] refer to Figure 2 and Figure 3 The sealing body 38 has a plurality of threaded portions 72 provided on the main lip 58. The plurality of threaded portions 72 are provided on the outer inclined surface 58b of the main lip 58. The plurality of threaded portions 72 extend spirally from the lip end 58a to the reverse inner space side S2. In this embodiment, the threaded portion 72 is constituted by a groove recessed into the outer inclined surface 58b. Alternatively, the threaded portion 72 may also be constituted by a rib protruding convexly on the outer inclined surface 58b. Figure 2 In the figure, reference numerals are marked within a certain axial range having multiple threaded portions 72.

[0041] Multiple threaded portions 72 constitute threaded regions 74A and 74B, which are parallel to each other. Threaded regions 74A and 74B constitute a portion of the circumferential range on the outer inclined surface 58b. Threaded regions 74A and 74B include: a forward-rotating threaded region 74A, which forms multiple threaded portions 72 extending axially toward one side of the circumference (hereinafter referred to as the forward rotation direction) toward the lip end 58a; and a reverse-rotating threaded region 74B, which forms multiple threaded portions 72 extending axially toward the other side of the circumference (hereinafter referred to as the reverse rotation direction) toward the lip end 58a. In the forward-rotating threaded region 74A and the reverse-rotating threaded region 74B, the helical directions of the multiple threaded portions 72 are opposite.

[0042] When the housing 16 and the inner component 18 rotate relative to each other, the multiple threaded portions 72, through a pumping action, perform a fluid delivery function to the contact portion of the main lip 58 relative to the main sealing surface 68, supplying fluid to the internal space side S1. For example, when the inner component 18 rotates relative to the housing 16 in the forward rotation direction, the multiple threaded portions 72 located in the forward rotation thread region 74A deliver fluid to the internal space side S1 through a pumping action. Furthermore, when the inner component 18 rotates relative to the housing 16 in the reverse rotation direction, the multiple threaded portions 72 located in the reverse rotation thread region 74B deliver fluid to the internal space side S1 through a pumping action. In this case, if the threaded portions 72 are formed by ribs, fluid between the multiple threaded portions 72 in each thread region 74A, 74B is delivered to the internal space side S1. Furthermore, if the threaded portions 72 are formed by grooves, fluid within the threaded portions 72 in each thread region 74A, 74B is delivered to the internal space side S1.

[0043] In this embodiment, the multiple threaded portions 72 constitute a forward-rotating threaded region 74A and a reverse-rotating threaded region 74B. Therefore, regardless of the relative rotation direction of the inner component 18 with respect to the housing 16, the fluid delivery function can be performed. When the rotation direction of the inner component 18 with respect to the housing 16 is determined, and this rotation direction is set to the forward rotation direction, the multiple threaded portions 72 may constitute only the forward-rotating threaded region 74A without constituting the reverse-rotating threaded region 74B.

[0044] In this way, the multiple threaded portions 72 perform a fluid delivery function when the housing 16 and the inner component 18 rotate relative to each other, thereby increasing the amount of fluid delivered to the inner space side S1. This fluid delivery function is due to the pumping force generated by the uneven pressure distribution between the lip end 58a of the main lip 58 and the main sealing surface 68, which acts separately from the pumping force that delivers fluid to the inner space side S1.

[0045] refer to Figure 2 The sealing body 38 includes a capturing part 76 capable of capturing foreign matter that intends to flow from the internal space 32 to the main lip 58. The capturing part 76 is provided separately from bearings such as the main bearing 42. In this embodiment, the capturing part 76 is composed of an auxiliary sealing member 78, which can capture foreign matter by blocking it from flowing from the internal space 32 to the main lip 58 along with the lubricant. The capturing part 76 is composed of a continuous annular body, similar to the auxiliary sealing member 78.

[0046] A gap space 80 is formed between the main sealing member 54 and the auxiliary sealing member 78. The gap space 80 is formed by at least the main sealing member 54 and the auxiliary sealing member 78 in a position sandwiched between these members. 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 disposed on the side that is radially opposite to the main sealing surface 68 of the main sealing member 54.

[0047] The auxiliary sealing component 78 includes a second main body portion 82 and an auxiliary lip portion 84 disposed on the second main body portion 82. The auxiliary sealing component 78 includes a second metal ring 86 and a second elastic material 88 integrally formed with the second metal ring 86 by means of vulcanization bonding or the like. The second elastic material 88 is made of rubber or the like. Alternatively, the auxiliary sealing component 78 may be composed of only either the second metal ring 86 or the second elastic material 88.

[0048] In this embodiment, the second main body portion 82 is mounted on the first main body portion 56. Alternatively, the second main body portion 82 may be mounted on the inner periphery of the housing 16 or on the outer periphery of the inner component 18. The second main body portion 82 includes a second mounting portion 82a that is mounted to a mounting object via an interference fit 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 either one may be used. 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.

[0049] The auxiliary lip 84 contacts the auxiliary sealing surface 90 provided in either the housing 16 or the inner component 18. Thus, the auxiliary sealing component 78 separates the gap space 80 and the internal space 32. The gap space 80 is sealed by at least the main sealing component 54 and the auxiliary sealing component 78. In this embodiment, the auxiliary sealing surface 90 is provided in the inner component 18. Based on the condition that it is provided in either the housing 16 or the inner component 18, the auxiliary sealing surface 90 can be formed by a portion of either the housing 16 or the inner component 18, or it can be formed by another component installed in either of them. In this embodiment, the auxiliary sealing surface 90 is formed by the circumferential surface of the inner component 18 itself, as described above. Furthermore, the example described in this embodiment is the same surface that is continuously connected to the main sealing surface 68 without any steps, but it can also be provided on a different surface or a different component than the main sealing surface 68. Furthermore, when the second main body part 82 is installed on the inner component 18 instead of the first main body part 56, the auxiliary sealing surface 90 only needs to be provided on the housing 16.

[0050] The auxiliary lip 84 extends from the radial end of the second radially extending portion 82b on the auxiliary sealing surface 90 side toward the auxiliary sealing surface 90 side. The auxiliary lip 84 is made of a second elastic material 88. The auxiliary lip 84 in this embodiment includes: a base end side portion 84a, which extends radially from the second radially extending portion 82b toward the auxiliary sealing surface 90 side; and a front end side portion 84b, which extends from the base end side portion 84a toward the inner space side S1 and contacts the auxiliary sealing surface 90. A recess 92 is formed between the second main body portion 82 and the auxiliary lip 84, recessed toward the anti-inner space side S2.

[0051] The above explains the effect of the speed reducer 10.

[0052] Each of the multiple threaded portions 72 is formed by a groove or a rib. In the contact area between the main lip 58 and the main sealing surface 68, when the threaded portion 72 is a groove, the main lip 58 has difficulty contacting the main sealing surface 68 at the location of the threaded portion 72. Furthermore, when the threaded portion 72 is a rib, the main lip 58 has difficulty contacting the main sealing surface 68 between the multiple threaded portions 72. Therefore, when multiple threaded portions 72 are provided on the main lip 58, the contact area between the main lip 58 and the main sealing surface 68 becomes smaller, tending to result in high surface pressure. As a result, the following problem exists: when multiple threaded portions 72 are provided on the main lip 58, as described above, due to the influence of foreign matter embedded in the internal space 32, the contact state between the main lip 58 and the main sealing surface 68 easily becomes unstable. This means that compared to the case where multiple threaded portions 72 are not provided on the main lip 58, the problems described herein are more likely to occur.

[0053] The reducer 10 of this embodiment includes a capturing section 76 that captures foreign objects that wish to flow from the internal space 32 to the main lip 58. Therefore, even if foreign objects such as abrasive powder are generated in the internal space 32 of the reducer, the amount of foreign objects reaching the main lip 58 from the internal space 32 can be reduced by capturing them with the capturing section 76. Furthermore, this helps to suppress the encroachment of foreign objects into the main lip 58, where multiple threaded portions 72 are provided. Moreover, by reducing the amount of foreign objects reaching the main lip 58 from the internal space 32, it is beneficial to maintain the sealing performance of the main lip 58 of the sealing body 38 over a long period.

[0054] The auxiliary sealing member 78 constituting the capturing section 76 isolates the gap space 80 from the internal space 32. Therefore, by cutting off the flow of foreign matter from the internal space 32 to the gap space 80 through the auxiliary sealing member 78, the amount of foreign matter reaching the main lip 58 from the internal space 32 can be further reduced. Furthermore, by introducing fluid into the gap space 80 through the multiple threaded portions 72 of the main lip 58, the pressure in the gap space 80 can be made higher than that in the internal space 32 of the reducer. This makes it difficult for foreign matter to flow from the low-pressure internal space 32 into the high-pressure gap space 80, reducing the amount of foreign matter reaching the main lip 58 via the gap space 80. This further facilitates the suppression of foreign matter from entering the main lip 58.

[0055] Next, other features of the reducer 10 will be described. The interference fit A (mm) of the main lip 58 relative to the main sealing surface 68 and the interference fit B (mm) of the auxiliary lip 84 relative to the auxiliary sealing surface 90 will be examined. The state in which the seal 38 is not assembled into the reducer 10 and the lips 58, 84 of the seal 38 are not deformed due to contact with other components is called the undeformed state. Furthermore, the state in which the seal 38 is assembled into the reducer 10 and the lips 58, 84 of the seal 38 are deformed due to contact with other components (sealing surfaces) is called the deformed state. The interference fits A and B represent the radial deformation of each lip 58, 84 when changing 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 58, 84 in the undeformed state and the diameter of the sealing surfaces 68, 90 that the lips 58, 84 contact.

[0056] For example, consider the case where component 50 becomes inner component 18, and the main sealing surface 68 and auxiliary sealing surface 90 constitute the outer peripheral surface of inner component 18. In this case, the interference fit A represents the outer diameter R68 of the main sealing surface 68 (reference). Figure 1 The interference amount B represents the difference between the outer diameter R90 of the auxiliary sealing surface 90 and the minimum inner diameter R84 of the auxiliary lip 84 in its undeformed state. In this case, the interference amount B represents the difference between the outer diameter R68 of the main sealing surface 68 and the minimum inner diameter R58 of the main lip 58, and the outer diameter R90 of the auxiliary sealing surface 90 and the minimum inner diameter R84 of the auxiliary lip 84. In this embodiment, in its undeformed state, the minimum inner diameter R58 of the main lip 58 is smaller than the minimum inner diameter R84 of the auxiliary lip 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.

[0057] Consider a component 50 referred to as housing 16, with the main sealing surface 68 and auxiliary sealing surface 90 forming the inner circumferential surfaces of housing 16. In this case, the interference A represents the difference between the inner diameter of the main sealing surface 68 and the maximum outer diameter of the main lip 58. Furthermore, the interference B represents the difference between the inner diameter of the auxiliary sealing surface 90 and the maximum outer diameter of the auxiliary lip 84. This is on the premise that the inner diameter of the main sealing surface 68 is less than the maximum outer diameter of the main lip 58 and the inner diameter of the auxiliary sealing surface 90 is less than the maximum outer diameter of the auxiliary lip 84.

[0058] In this embodiment, the interference fit A of the main lip 58 is greater than the interference fit B of the auxiliary lip 84. Therefore, compared to setting the interference fit A of the main lip 58 to be the same as the interference fit B of the auxiliary lip 84, the surface pressure of the main lip 58 relative to the main sealing surface 68 can be increased, thereby improving the sealing performance based on the main lip 58. Furthermore, compared to setting the interference fit B of the auxiliary lip 84 to be the same as the interference fit A of the main lip 58, the surface pressure of the auxiliary lip 84 relative to the auxiliary sealing surface 90 can be decreased, thereby reducing frictional losses caused by the contact between the auxiliary sealing surface 90 and the auxiliary lip 84.

[0059] Furthermore, in order to increase the surface pressure of the main lip 58 while reducing the surface pressure of the auxiliary lip 84, the rigidity of the main lip 58 can be made higher than that of the auxiliary lip 84. To increase the rigidity of the main lip 58, the radial dimension of its base end portion can be increased. And, to reduce the rigidity of the auxiliary lip 84, the axial dimension of its base end portion 84a can be decreased.

[0060] At least a portion of the front end portion 84b of the auxiliary lip 84 is configured to extend axially toward the inner space 32 towards the front end. Therefore, as the pressure in the gap space 80 increases relative to the pressure in the inner space 32, the auxiliary lip 84 easily deforms to displace toward the inner space S1. This deformation of the auxiliary lip 84 temporarily creates a gap between the auxiliary lip 84 and the auxiliary sealing surface 90, connecting the gap space 80 and the inner space 32, through which the pressure in the gap space 80 can be released to the inner space 32. This deformation of the auxiliary lip 84 occurs when the pressure difference ΔP (=P1-P2) between the pressure P1 in the gap space 80 and the pressure P2 (<P1) in the inner space 32 reaches at least a predetermined pressure. The units of each pressure P1 and P2 are Pa.

[0061] When the pressure exceeds a predetermined value, the rigidity of the auxiliary lip 84, the interference fit B of the auxiliary lip 84, and the length of the contact portion of the auxiliary lip 84 relative to the auxiliary sealing surface 90 can be adjusted to induce deformation of the auxiliary lip 84. Higher rigidity, larger interference fit B, and longer contact portion of the auxiliary lip 84 relative to the auxiliary sealing surface 90 make the auxiliary lip 84 less prone to deformation, thus increasing the pressure difference ΔP that causes deformation of the auxiliary lip 84. To improve the rigidity of the auxiliary lip 84, for example, the axial dimension of the base end portion 84a of the auxiliary lip 84 can be increased. Furthermore, when the pressure difference ΔP reaches at least a predetermined value, the auxiliary lip 84 is configured to release the pressure of the clearance space 80 to the internal space 32.

[0062] In addition, in order to reduce the pressure difference ΔP that causes deformation of the auxiliary lip 84, any one of the following (1), (2) and (3) can be satisfied. The length of the contact portion in (2) is, for example, the axial length of the contact portion. Thus, compared with the case where none of the conditions are satisfied, when the specified pressure is reached, the auxiliary lip 84 is more likely to deform, and the pressure of the gap space 80 can be reliably released to the inner space 32 side.

[0063] (1) Make the Young's modulus of the auxiliary lip 84 lower than that of the main lip 58 (N / mm) 2 ).

[0064] (2) Make the length (mm) of the contact portion of the auxiliary lip 84 relative to the auxiliary sealing surface 90 smaller than the length (mm) of the contact portion of the main lip 58 relative to the main sealing surface 68.

[0065] (3) Set the interference A of the main lip 58 to be greater than the interference B of the auxiliary lip 84.

[0066] According to this embodiment, fluid is fed into the gap space 80 through the multiple threaded portions 72 of the main lip 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 58 may experience excessive frictional wear and other adverse effects due to the excessive increase in the pressure P1 in the gap space 80. Here, the auxiliary lip 84 of this embodiment is configured such that 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 or exceeds a predetermined pressure, the pressure in the gap space 80 can be released to the internal space 32 side. As a result, excessive increase in the pressure P1 in the gap space 80 can be suppressed, thereby suppressing the occurrence of adverse effects caused therefrom.

[0067] Lubricant can also be sealed in the gap space 80. The lubricant sealed in the 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) can be the same or different. For example, when using grease as the lubricant, the consistency of the gap space lubricant can be set to be higher than that of the internal space lubricant. Furthermore, when using lubricating oil as the lubricant, the viscosity of the gap space lubricant can be set to be higher than that of the internal space lubricant. As a result, the lubricant can easily remain in the gap space 80, which helps to suppress the leakage of lubricant into the outer space 48.

[0068] (Second Implementation) Reference Figure 4 and Figure 5 In the following embodiments, among the constituent elements described in the first embodiment, the constituent elements not described below may be the same as those in the first embodiment.

[0069] The structure of the auxiliary lip 84 of the seal 38 of the reducer 10 in this embodiment differs. An example was described where the interference B of the auxiliary lip 84 relative to the auxiliary sealing surface 90 in the first embodiment was smaller than the interference A of the main lip 58 relative to the main sealing surface 68. In this embodiment, the interference B of the auxiliary lip 84 relative to the auxiliary sealing surface 90 is larger than the interference A of the main lip 58 relative to the main sealing surface 68. To achieve this, in this embodiment, in its undeformed state, the minimum inner diameter R84 of the auxiliary lip 84 is smaller than the minimum inner diameter R58 of the main lip 58. 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. Therefore, compared to setting the interference B of the auxiliary lip 84 to be the same as the interference A of the main lip 58, the surface pressure of the auxiliary lip 84 relative to the auxiliary sealing surface 90 can be increased, thereby improving the sealing performance of the auxiliary lip 84.

[0070] In the first embodiment, an example was described where the auxiliary lip 84 is located further inward than the innermost space side S2 than the position 82c of the second radial extension 82b, which is the innermost space side S1. In this embodiment, the auxiliary lip 84 extends to the inner space side S1 of the position 82c of the second radial extension 82b, which is the innermost space side S1. This increases the contact area of ​​the auxiliary lip 84 with respect to the auxiliary sealing surface 90, thereby improving the sealing performance based on the auxiliary lip 84.

[0071] Furthermore, the speed reducer 10 according to this embodiment can achieve the same effect as the first embodiment within a range that does not contradict the first embodiment.

[0072] Next, variations of the constituent elements described so far will be explained.

[0073] The capturing section 76 can also attract foreign objects made of soft magnetic materials using magnetic force. The specific means to achieve this are not particularly limited. For example, magnetic powder made of a magnetized strong magnetic material can be mixed into the second elastic material 88 of the capturing section 76. Alternatively, the second metal ring 86 of the capturing section 76 can be made of a magnetized strong magnetic material. Furthermore, a magnetized strong magnetic material such as a permanent magnet can be assembled in a part of the capturing section 76. In any case, as long as a strong magnetic material capable of attracting foreign objects using magnetic force is provided in at least a part of the capturing section 76, it is acceptable. Thus, by using the capturing section 76 to attract foreign objects made of soft magnetic materials, the amount of foreign objects reaching the main lip 58 from the internal space 32 can be reduced. Furthermore, this helps to suppress the biting of foreign objects into the main lip 58.

[0074] 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 an eccentric oscillating type reduction mechanism, a flexural meshing type reduction mechanism (including cylindrical, top-hat, and cup types), a simple planetary mechanism, etc., can also be used as the reduction mechanism 14. When an eccentric oscillating type reduction mechanism is used as the reduction mechanism 14, its specific type is not particularly limited. In this embodiment, a central crankshaft type with the crankshaft 24 located on the rotation center line C20 of the output member 20 is described. Alternatively, a distribution type can be used where the crankshaft 24 is located at a position radially offset from the rotation center line C20 of the output member 20. When an eccentric oscillating type reduction mechanism is used as the reduction mechanism 14, the internal gear 28 can be oscillated instead of the external gear 26. In this case, the oscillation of the internal gear 28 causes the external gear 26 to rotate, and the rotation of the external gear 26 is transmitted to the inner member 18, which becomes the output member 20, thereby outputting rotation from the inner member 18. At this time, the inner component 18 rotates integrally with the outer gear 26, thereby synchronizing with the rotation of the outer gear 26. Thus, the inner component 18 is not limited to a bracket that synchronizes with the rotational component of the outer gear 26 via a pin or the like, but can also be a component that synchronizes with the rotational component of the outer gear 26 by rotating integrally with it, or it can be formed by the outer gear 26 itself.

[0075] In the case of eccentric oscillating type deceleration devices and flexural meshing type deceleration devices, the lubricant in the internal space 32 tends to flow along with foreign matter as the vibrating body or crankshaft rotates, thus making it easier for foreign matter to reach between the main lip 58 and the main sealing surface 68. By applying the sealing body 38 of this embodiment, even in this case, it is possible to effectively suppress the biting of foreign matter into the main lip 58.

[0076] The placement of the sealing element 38 is not particularly limited. For example, it can be placed between the housing 16 and the inner component 18, or between the input component 12 and the inner component 18. Furthermore, it can be placed between the housing 16 and the first inner component 18A, or between the housing 16 and the second inner component 18B. Alternatively, it can be placed only between the housing 16 and the second inner component 18B. Furthermore, the sealing element 38 of this disclosure can be placed between one of the first inner component 18A and the second inner component 18B and the housing 16, while other sealing components can be placed between the other and the housing 16.

[0077] The auxiliary sealing member 78 constituting the capturing part 76 may not have an auxiliary lip 84 that contacts the auxiliary sealing surface 90. In this case, the gap space 80 and the internal space 32 can be connected. Alternatively, the capturing part 76 may not have the function of blocking foreign objects, like the auxiliary sealing member 78, but may be able to attract foreign objects by magnetic force, as described above, thereby capturing foreign objects that want to flow from the internal space 32 to the main lip 58 side.

[0078] When the gap space 80 and the internal space 32 are separated, the second main body 82 of the auxiliary sealing member 78 can be mounted on the housing 16. In this case, the auxiliary lip 84 of the auxiliary sealing member 78 only needs to contact the auxiliary sealing surface 90 provided on the inner member 18. Furthermore, the second main body 82 of the auxiliary sealing member 78 can also be mounted on the inner member 18. In this case, the auxiliary lip 84 of the auxiliary sealing member 78 only needs to contact the auxiliary sealing surface 90 provided on the housing 16.

[0079] The interference amount A of the main lip 58 and the interference amount B of the auxiliary lip 84 are not particularly limited. These interference amounts A and B can be the same. The auxiliary lip 84 can be configured to release the pressure of the gap space 80 to the inner space 32 side when the pressure difference ΔP between the pressure P1 of the gap space 80 and the pressure P2 of the inner space 32 becomes a predetermined pressure or higher.

[0080] The components described in the above embodiments are examples. These abstract technical concepts should not be interpreted solely within the scope of this specification. The components described in the embodiments can be modified, added to, or deleted in various design changes. For components that can undergo such design changes, the terms "this embodiment" or "implementation" are used and emphasized. However, this does not mean that design changes are not permitted for components not described in this way. Any combination of the above components is also valid. For example, any description of other embodiments can be combined with an embodiment, and any description of embodiments and other modifications can be combined with a variation. The shaded lines on the cross-sections of the drawings are not limited to the material of the objects shaded. The structures and values ​​mentioned in the embodiments and modifications naturally include structures and values ​​that can be considered the same when considering manufacturing errors, etc. In the descriptions in this specification, a component consisting of one part can also be consisting of multiple parts. Similarly, a component consisting of multiple parts can also be consisting of one part.

Claims

1. A speed reducer, comprising: The speed reduction mechanism has external gears and internal gears that mesh with each other; The housing has an internal space on its inner side that accommodates at least a portion of the deceleration mechanism; An inner component, disposed inside the housing; and A sealing element is disposed between the housing and the inner component. One of the housing and the inner component becomes the output component for output rotation. The sealing body comprises: The main lip contacts the main sealing surface of one of the components that forms one of the housing and the inner component; Multiple threaded portions are provided on the main lip, and when the housing and the inner component rotate relative to each other, the amount of fluid fed axially into the internal space increases; and The capturing unit is capable of capturing foreign objects that are about to flow from the internal space to the main lip side.

2. The speed reducer according to claim 1, wherein, The sealing body includes a main sealing component having the main lip and an auxiliary sealing component constituting the capturing portion. A gap space is formed between the main sealing component and the auxiliary sealing component. The auxiliary sealing component separates the gap space from the internal space.

3. The speed reducer according to claim 2, wherein, The auxiliary sealing component has an auxiliary lip that contacts the auxiliary sealing surface disposed on either the inner component or the housing. The interference fit of the main lip relative to the main sealing surface is greater than the interference fit of the auxiliary lip relative to the auxiliary sealing surface.

4. The speed reducer according to claim 2, wherein, The auxiliary sealing component has an auxiliary lip that contacts the auxiliary sealing surface disposed on either the inner component or the housing. The auxiliary lip is configured such that when the pressure difference ΔP between the pressure P1 in the gap space and the pressure P2 in the inner space becomes a predetermined pressure or higher, the pressure in the gap space can be released to the inner space side, where P2 < P1.

5. The speed reducer according to claim 1, wherein, The capturing unit can attract foreign objects using magnetic force.

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