Power transmission device

Abstract

The invention provides a power transmission device which is beneficial for suppressing lubricant leakage caused by pumping force when an internal space is sealed by a sealing member. The power transmission device is provided with: a pair of relative rotating bodies (16) that rotate relative to each other; and a seal member (10) disposed between the pair of opposed rotating bodies (16). The seal member (10) is provided with a lip section (28) that is in contact with a first relative rotating body (18), which is one of the pair of relative rotating bodies (16), and a spring member that presses the lip section toward the first relative rotating body is not attached to the lip section (28). The lip portion (28) is provided with a first corner portion (28a) provided at a position radially facing the first relative rotating body (18), and an axial contact length (La) of the lip portion (28) with the first relative rotating body on a side axially opposite to the inner space than the first corner portion is longer than an axial contact length (Lb) of the lip portion (28) with the first relative rotating body on a side of the inner space that is closer to the first corner portion than the first corner portion.

Description

[0001] This application claims priority based on Japanese Patent Application No. 2024-182206, filed on October 17, 2024. The entire contents of that Japanese application are incorporated herein by reference. Technical Field

[0002] This invention relates to a power transmission device. Background Technology

[0003] Patent Document 1 discloses a power transmission device with a speed reducer. The power transmission device includes a pair of opposing rotating bodies that rotate relative to each other, and a sealing member disposed between the pair of opposing rotating bodies.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2006-283981

[0005] In the power transmission device of Patent Document 1, a spring-loaded sealing member is used as the sealing component, on which a spring component is mounted. The spring-loaded sealing member presses the corner of the lip of the sealing member against the contact object by the spring component, causing local deformation of the lip. By utilizing the pumping force generated between the lip and the contact object, the internal space of the power transmission device can be sealed.

[0006] Therefore, when the internal space is sealed using pumping force, the following problem arises: air is drawn into the outer space, which is located on the side opposite to the axial direction of the internal space relative to the sealing component, by the pumping force. This causes the internal pressure of the internal space to rise, and lubricant leakage is likely to occur due to the pumping force. Here, lubricant leakage refers to the leakage of lubricant sealed inside the internal space into the outer space. Summary of the Invention

[0007] Therefore, one object of the present invention is to provide a power transmission device that, when the internal space is sealed by a sealing component, helps to suppress lubricant leakage caused by pumping force.

[0008] The power transmission device of the present invention is a power transmission device equipped with a speed reducer, comprising: a pair of opposing rotating bodies that rotate relative to each other; and a sealing member disposed between the pair of opposing rotating bodies and used to seal the internal space of the power transmission device. The sealing member has a lip that contacts one of the pair of opposing rotating bodies, namely a first opposing rotating body. No spring member is installed on the lip to press the lip towards the first opposing rotating body. The lip has a corner portion disposed at a position radially opposite to the first opposing rotating body. The axial contact length of the lip with the first opposing rotating body on the side further axially opposite to the corner portion is longer than the axial contact length of the lip with the first opposing rotating body on the internal space side further axially than the corner portion.

[0009] Invention Effects

[0010] According to the power transmission device of the present invention, when the internal space is sealed by a sealing component, it is advantageous to suppress lubricant leakage caused by pumping force. Attached Figure Description

[0011] Figure 1 This is a side sectional view showing the sealing member in a deformed state according to the first embodiment.

[0012] Figure 2 This is a side sectional view showing the sealing member in an undeformed state in the first embodiment.

[0013] Figure 3 Figure (A) is a side sectional view showing the sealing member in a deformed state in the second embodiment, and Figure (B) is an enlarged view of a portion of Figure (A).

[0014] Figure 4 This is a side sectional view showing the sealing member in a deformed state according to the third embodiment.

[0015] Figure 5 This is a side sectional view showing the sealing member in an undeformed state according to the third embodiment.

[0016] Figure 6 This is a side sectional view showing the power transmission device of the fourth embodiment.

[0017] Figure 7 This is a side sectional view showing the power transmission device of the fifth embodiment.

[0018] Figure 8 This is a side sectional view showing the power transmission device of the sixth embodiment.

[0019] Figure 9This is a side sectional view showing the power transmission device of the seventh embodiment.

[0020] Figure 10 This is a side sectional view showing a portion of the power transmission device according to the eighth embodiment.

[0021] In the diagram: 10-Sealing component, 12-Reducer, 14-Power transmission device, 16, 16-A, 16-B-Paired relative rotating bodies, 16-A-Paired high-speed relative rotating bodies, 16-B-Paired low-speed relative rotating bodies, 18-First relative rotating body, 20-Second relative rotating body, 22-Internal space, 24-Outer space, 28-Lip, 28a-Corner, 28b-Front end face, 32-Contact area, 34-Groove, 42-Reduction mechanism, 48-Vibration starter, 50-Vibration starter shaft, 72-Crankshaft, 74-Oscillating gear, 118-Reducer rotating shaft, 130-Torque transmission mechanism, 134-Rotating body. Detailed Implementation

[0022] Hereinafter, embodiments of the power transmission device for implementing the present invention will be described. Identical or equivalent elements are labeled with the same symbols, and repeated descriptions are omitted. In the accompanying drawings, constituent elements are appropriately omitted, enlarged, or reduced for ease of explanation. The drawings are viewed according to the direction of the symbols.

[0023] (First Embodiment) Reference Figure 1 First, the sealing member 10 of the first embodiment will be described. The sealing member 10 is used in a power transmission device 14 that includes a speed reducer 12. In addition to the sealing member 10, the power transmission device 14 also includes a pair of opposing rotating bodies 16 that rotate relative to each other. The details of the power transmission device 14 will be described later. Hereinafter, the direction along the rotation center line (not shown) when the pair of opposing rotating bodies 16 rotate relative to each other will be referred to as the axial direction, and the radial direction and circumferential direction based on the rotation center line will be referred to as the radial direction and circumferential direction, respectively.

[0024] The paired relative rotating bodies 16 include a first relative rotating body 18 and a second relative rotating body 20. The first relative rotating body 18 has a lip contact surface 18a that contacts the lip 28 of the sealing member 10. The second relative rotating body 20 has a fixed surface 20a for fixing the sealing member 10. In this embodiment, the first relative rotating body 18 is located radially inward relative to the second relative rotating body 20, but it may also be located radially outward relative to the second relative rotating body 20.

[0025] The sealing member 10 is disposed between a pair of opposing rotating bodies 16 and is used to seal the internal space 22 of the power transmission device 14. Hereinafter, the sealing member 10 will be described on the axial side adjacent to the internal space 22. Figure 1The right side of the paper is called the axial inner side, and the side opposite to the axial direction of the internal space 22 is called the inner side. Figure 1 The left side of the paper is referred to as the axial outer side. The sealing member 10 separates the outer space 24, which is located axially outside the sealing member 10, from the inner space 22.

[0026] The sealing member 10 includes a main body 26 and a lip 28 (first lip) provided on the main body 26. The main body 26 is fixed by an interference fit with the fixed surface 20a of the second relative rotating body 20. Alternatively, as an arbitrary structure, the sealing member 10 may also include a dustproof lip 30 (second lip) protruding from the lip 28.

[0027] In this embodiment, the main body 26 is made of an elastic material such as rubber. Alternatively, the main body 26 may be composed of a combination of a metal ring and an elastic material, or only a metal ring. The lip 28 is made of an elastic material such as rubber. In this embodiment, the lip 28 is made of the same elastic material as the main body 26.

[0028] The main body 26 of this embodiment is L-shaped in cross-section cut along the axial direction, but its specific shape is not particularly limited. The main body 26 of this embodiment includes: an axially extending portion 26a that extends axially and is fixed to the second relative rotating body 20; and a radially extending portion 26b that extends radially from the outer axial end of the axially extending portion 26a toward the first relative rotating body 18.

[0029] refer to Figure 1 and Figure 2 When the lip 28 of the sealing member 10 is in contact with the first relative rotating body 18, it becomes a deformed state due to contact with the first relative rotating body 18 (see reference). Figure 1 In contrast, when the lip 28 is not in contact with the first relative rotating body 18, it becomes an undeformed state (see reference). Figure 2 The premise is that, regardless of whether the lip 28 is in a deformed state or not, the sealing member 10 is fixed to the second relative rotating body 20. The undeformed state is also the state that can be presented when the lip 28 of the sealing member 10 is released from contact with the first relative rotating body 18 while it is fixed to the second relative rotating body 20.

[0030] The lip 28 is used to prevent leakage of lubricant sealed within the internal space 22. The lip 28 extends axially inward from the outer portion of the main body 26. When the lip 28 is in its undeformed state, it extends axially inward and close to the radially opposing first rotating body 18. When the lip 28 is in its deformed state, it elastically bends and deforms compared to its undeformed state, with its front end bending radially in the opposite direction to the first rotating body 18. When the lip 28 is in its deformed state, a pressing force F1 acts radially against the first rotating body 18. This pressing force F1 acts as a reaction force caused by the elastic bending deformation of the lip 28.

[0031] The lip 28 includes: a first corner portion 28a, which is located radially opposite to the first relative rotating body 18; a front end face 28b, which is continuous with the first corner portion 28a; a first side face 28c, which is continuous with the first corner portion 28a; a second corner portion 28d, which is located on the front end face 28b on the side radially opposite to the first corner portion 28a; and a second side face 28e, which is continuous with the second corner portion 28d.

[0032] In this specification, the term "first corner portion 28a" differs from its usual meaning. It refers to the portion of the lip 28 that protrudes radially toward the first opposing rotating body 18 on a surface cut along the axial direction when the lip 28 is in its undeformed state. Alternatively, the first corner portion 28a is the portion that contacts the dotted line parallel to the axial direction from the first opposing rotating body 18 side on a surface cut along the axial direction. Thus, when considering the first corner portion 28a, the presence of another lip extending from the lip 28 (e.g., the dustproof lip 30 described later) is not considered. The first corner portion 28a is formed by a portion of the first side surface 28c and a portion of the front end surface 28b. The portion of the first side surface 28c extends radially toward the second opposing rotating body 20 side from its position in the lip 28 that is radially closest to the first opposing rotating body 18, toward a side opposite to the axial direction of the internal space 22. A portion of the front end face 28b extends radially toward the second relative rotating body 20 from that position toward the axially inclined inner space 22. In this embodiment, the first corner portion 28a is formed as follows: when the lip 28 is in an undeformed state, it is the portion radially closest to the first relative rotating body 18 among the pointed portions protruding radially toward the first relative rotating body 18. Alternatively, the first corner portion 28a may also be formed as follows: when the lip 28 is in an undeformed state, it is the portion radially closest to the first relative rotating body 18 among the curved portions protruding radially toward the first relative rotating body 18.

[0033] The front end face 28b faces the inner space 22 axially and is located at the innermost axial position of the lip 28. In this embodiment, when the lip 28 is deformed, the front end face 28b is positioned perpendicular to the lip contact surface 18a on a surface cut along the axial direction. "Perpendicular" here includes not only geometrically perpendicular to the lip contact surface 18a, but also substantially perpendicular to it. For example, "substantially perpendicular" includes a position within ±10° of the position strictly perpendicular to the lip contact surface 18a. Similar to the first corner 28a, the first side face 28c is positioned radially opposite to the first relative rotating body 18. The second side face 28e faces the side radially opposite to the first side face 28c.

[0034] The dustproof lip 30 is configured to prevent dust from entering the inner space 22 from the outer space 24. The dustproof lip 30 extends axially outward from the lip 28 and comes into contact with the lip contact surface 18a of the first relative rotating body 18 through elastic deformation.

[0035] No spring component is installed on the lip 28 to press against the first relative rotating body 18. For example, this spring component refers to a continuous annular spring without a joint. This spring component is separate from the lip 28 and is installed on the second side 28e of the lip 28.

[0036] The overall axial contact length between the lip 28 and the first relative rotating body 18 is called the contact length L0. Here, the axial contact length refers to the axial length of the contact portion between the lip 28 and the first relative rotating body 18. When considering the overall contact length L0 of the lip 28, as... Figure 4 As shown, when the lip 28 contacts the first relative rotating body 18 at multiple contact points spaced apart axially, the sum of the axial lengths of the multiple contact points is used. For example, in Figure 4 The diagram shows an example where the lip 28 contacts the first relative rotating body 18 at four contact points, i.e., the contact lengths of each contact point are L0(1) to L0(4). In this case, the overall contact length L0 of the lip 28 is the sum of the contact lengths L0(1) to L0(4). When considering the overall contact length L0 of the lip 28, for example, the axial length of the contact point between another lip protruding from the lip 28, such as the dustproof lip 30, and the first relative rotating body 18 is not considered. The concepts described here also apply to the outer contact length La and the inner contact length Lb, which will be explained below.

[0037] The axial contact length between the lip 28 and the first opposing rotating body 18, which is axially outer of the first corner 28a of the sealing member 10, is called the outer contact length La. The axial contact length between the lip 28 and the first opposing rotating body 18, which is axially inner of the first corner 28a of the sealing member 10, is called the inner contact length Lb. The outer contact length La is also the overall contact length between the first side surface 28c and the first opposing rotating body 18. The inner contact length Lb is also the overall contact length between the front end surface 28b and the first opposing rotating body 18. The overall contact length L0 of the lip 28 is the sum of the outer contact length La and the inner contact length Lb of the lip 28.

[0038] In this embodiment, the characteristic is that the outer contact length La of the lip 28 is longer than the inner contact length Lb. When this length condition is met, there are sometimes cases where (1) the inner contact length Lb of the lip 28 is zero and (2) the inner contact length Lb of the lip 28 is greater than or equal to zero. Figure 1 In the above, case (1) is represented. In this case, the length condition is satisfied regardless of the size of the outer contact length La of the lip 28. In this case, the overall contact length L0 of the lip 28 is equal to the outer contact length La of the lip 28. In this case, the contact mode is as follows: only the first side surface 28c of the front end surface 28b and the first side surface 28c of the lip 28 contacts the first relative rotating body 18, and the front end surface 28b does not contact the first relative rotating body 18 (hereinafter, it is called the surface contact mode).

[0039] Figure 3 Figures (A) and (B) show the sealing member 10 of the second embodiment, illustrating the situation described in (2) above. Figure 3 In Figure (B), the lip 28 in its deformed state is represented by a solid line, and a portion of the lip 28 in its undeformed state is represented by a double-dotted line. In the case of (2) described above, the contact occurs as follows: as the portion of the lip 28 including the first corner 28a is compressed and deformed, both the front end face 28b and the first side face 28c come into contact with the first relative rotating body 18 (hereinafter referred to as angular contact). At this time, the first corner 28a of the lip 28, together with a portion of the front end face 28b and the first side face 28c of the lip 28, is flat and extends axially along a surface cut along the axial direction. That is, when the lip 28 is in its deformed state, the portion of the lip 28 including the first corner 28a does not protrude radially toward the first relative rotating body 18. Figure 3 In Figure (B), for ease of explanation, the position of the first corner 28a of the lip 28 in the deformed state is marked with a symbol.

[0040] As described in (1) above, the advantage of satisfying the above-mentioned length condition by making the inner contact length Lb of the lip 28 zero, i.e., the advantage of the surface contact form, will be explained. Assuming that the inner contact length Lb of the lip 28 is greater than zero, it becomes as follows: Figure 3 Such an angular contact method. In the angular contact method, a method for extending the overall contact length L0 of the lip 28 was studied. As a method for this purpose, the following first method can be conceived: during the assembly of the sealing member 10, the bending deformation of the lip 28 is increased, so that the first side surface 28c of the lip 28 deforms significantly in accordance with the lip contact surface 18a of the first relative rotating body 18. In addition, the following second method can be conceived: using a spring member, the pressing force that presses the lip 28 against the first relative rotating body 18 is applied to the lip 28, thereby increasing the amount of compression deformation of the portion of the lip 28 including the first corner 28a.

[0041] In the case of angular contact, if the first method results in a large bending deformation of the lip 28, the front end face 28b of the lip 28 cannot contact the first relative rotating body 18, thus making it impossible to maintain the angular contact. Therefore, in the case of angular contact, it is impractical to use the first method to increase the overall contact length L0 of the lip 28. Furthermore, in this embodiment, since no spring component is installed on the lip 28 of the sealing member 10, the second method cannot be used either. Therefore, in the case of angular contact, neither the first nor the second method can be used, and even if one wants to extend the overall contact length L0 of the lip 28, the extension is limited.

[0042] In contrast, in the case of surface contact, it is not necessary for the front end face 28b of the lip 28 to contact the first relative rotating body 18 as in the case of corner contact. Therefore, in this case, the bending deformation of the lip 28 can be easily increased using the first method, and consequently, the overall contact length L0 of the lip 28 can be easily increased. As a result, compared to the case of corner contact, the contact pressure exerted by the lip 28 on the first relative rotating body 18 can be easily reduced. Here, contact pressure refers to the force per unit area acting on the contact position between the lip 28 and the contact object.

[0043] Next, as described in (2) above, when the inner contact length Lb of the lip 28 is greater than zero, that is, in the case of angular contact, the advantages of satisfying the above-mentioned length condition will be explained. In this case, compared with the case where the outer contact length La of the lip 28 is the same as the inner contact length Lb, the overall contact length L0 of the lip 28 can be extended. Therefore, compared with the case where the outer contact length La and the inner contact length Lb are the same, the contact pressure exerted by the lip 28 on the first relative rotating body 18 can be substantially reduced.

[0044] In summary, when the length condition is met, the case where the inner contact length Lb of the lip 28 is zero (the case of surface contact) is investigated, as in (1). In this case, compared to the case where the inner contact length Lb is greater than zero (the case of corner contact), the overall contact length L0 of the lip 28 can be easily extended, and consequently, the contact pressure exerted by the lip 28 on the first relative rotating body 18 can be easily reduced. In this case, compared to the case of corner contact, the difficulty of extending the overall contact length L0 of the lip 28 can be reduced, and the difficulty of reducing the contact pressure of the lip 28 can be reduced.

[0045] Next, when the length condition is met, as in (2), the case where the inner contact length Lb of the lip 28 is greater than zero is investigated. In this case, compared with the case where the outer contact length La is set to be the same as the inner contact length Lb, the overall contact length L0 of the lip 28 can actually be extended, and consequently, the contact pressure applied by the lip 28 to the first relative rotating body 18 can actually be reduced.

[0046] It can be said that, when the length condition is met, even in either case (1) or (2), it is advantageous to extend the overall contact length L0 of the lip 28 compared to the specific case, and it is also advantageous to reduce the contact pressure of the lip 28. The specific case here refers to the case where, for (1), the inner contact length Lb is greater than zero (the case of angular contact), and for (2), the outer contact length La and the inner contact length Lb are set to be the same.

[0047] The effects of the power transmission device 14 using the aforementioned sealing component 10 will be explained.

[0048] (A) It is known that reducing the contact pressure at the contact point between the lip 28 of the sealing member 10 and the contact object can reduce the pumping force. Here, the sealing member 10 of this embodiment does not have a spring member mounted on the lip 28. Therefore, compared to a sealing member with a spring, the contact pressure exerted by the lip 28 on the first relative rotating body 18, which is the contact object, can be effectively reduced. Furthermore, by satisfying the aforementioned length condition, as described above, it is advantageous to reduce the contact pressure exerted by the lip 28 on the first relative rotating body 18. This, in turn, significantly reduces the pumping force generated between the first relative rotating body 18 and the lip 28. The internal space 22 is sealed primarily by the pressing force F1 generated by the lip 28, independent of the pumping force. Therefore, it is possible to suppress the increase in internal pressure of the internal space 22 caused by the pumping force, which is beneficial for suppressing lubricant leakage caused by the pumping force.

[0049] (B) When using a spring-loaded sealing component, the contact pressure at the lip 28 becomes very high due to the pressing force of the spring component. This causes the following problem: when the power transmission device 14 is operating under high acceleration or deceleration, the lip 28 twists relative to the first relative rotating body 18, which easily leads to lubricant leakage. In this respect, according to this embodiment, as described above, it is advantageous to reduce the contact pressure exerted by the lip 28 on the first relative rotating body 18. Therefore, when the power transmission device 14 is operating under high acceleration or deceleration, the lip 28 is less likely to twist relative to the first relative rotating body 18, thereby helping to suppress the resulting lubricant leakage.

[0050] (C) In this embodiment, the sealing member 10 only contacts the first side surface 28c with the first relative rotating body 18, achieving a surface contact state as described above. Therefore, compared to the angular contact state, by increasing the bending deformation of the lip 28, the first side surface 28c of the lip 28 can easily deform significantly to conform to the lip contact surface 18a of the first relative rotating body 18, thereby easily increasing the overall contact length L0 of the lip 28. Therefore, compared to a sealing member with a spring, the contact pressure applied by the lip 28 to the first relative rotating body 18 can be easily reduced, which is beneficial for significantly reducing the pumping force generated between the lip 28 and the first relative rotating body 18. As a result, the increase in internal pressure of the internal space 22 caused by the pumping force can be significantly suppressed, especially beneficial for suppressing lubricant leakage caused by the pumping force.

[0051] Next, another feature of the sealing member 10 will be described. (See reference...) Figure 2 The axial length L28b of the front end face 28b of the lip 28 is assumed to be in an undeformed state. This axial length L28b refers to the axial length from the first corner 28a of the lip 28 to the position furthest axially inward at the front end face 28b when the lip 28 is in an undeformed state. The contact length L0 can also preferably be longer than the axial length L28b. More preferably, the contact length L0 can be set to be more than twice the axial length L28b. The relationship between the upper limit of the contact length L0 and the axial length L28b is not particularly limited; for example, it can be set to less than 20 times the axial length L28b. From a manufacturing perspective, it can be appropriately set within a practical range.

[0052] (D) Therefore, compared to the case where the contact length L0 is less than or equal to the axial length L28b, the contact pressure exerted by the lip 28 on the first relatively rotating body 18 can be significantly reduced, thereby significantly reducing the pumping force. Furthermore, the increase in internal pressure of the internal space 22 caused by the pumping force can be significantly suppressed, which is particularly beneficial for suppressing lubricant leakage. Alternatively, the contact length L0 can also be less than or equal to the axial length L28b.

[0053] Assume a minimum thickness T of the lip 28 at the contact point between the lip 28 and the first relative rotating body 18. This minimum thickness T refers to the minimum radial thickness of the lip 28 at the point where the contact points of the lip 28 and the first relative rotating body 18 overlap. When considering the minimum thickness T, neglect considerations such as... Figure 4 Such thickness of the lip 28 at the non-contact portion between the lip 28 and the first opposing rotating body 18. For example, the non-contact portion of the lip 28 here refers to, as... Figure 4 That is, the portion that overlaps radially with the groove 34. Figure 2 In this method, the minimum thickness T is at the location where it overlaps radially with the first corner 28a of the lip 28, but it can also be at a different location.

[0054] At this point, the overall contact length L0 of the lip 28 can preferably be longer than the minimum thickness T. The relationship between the upper limit of this contact length L0 and the minimum thickness T is not particularly limited. For example, it can be set to less than 10 times the minimum thickness T. From a manufacturing perspective, it can also be appropriately set within a practical range.

[0055] (E) Therefore, compared to the case where the contact length L0 is less than or equal to the minimum thickness T, the contact pressure exerted by the lip 28 on the first relative rotating body 18 can be significantly reduced, thereby significantly reducing the pumping force. Furthermore, the increase in internal pressure of the internal space 22 caused by the pumping force can be significantly suppressed, which is particularly beneficial for suppressing lubricant leakage caused therefrom. In addition, the contact length L0 can also be less than or equal to the minimum thickness T.

[0056] The lubricant enclosed in the internal space 22 may contain at least one of Mo (molybdenum), S (sulfur), Ca (calcium), Zn (zinc), Ba (barium), Mg (magnesium), P (phosphorus), C (carbon), B (boron), and W (tungsten). For example, the lubricant may also be a common grease containing at least one of these.

[0057] (F) It is known that when using such a lubricant, precipitates are generated due to heat. If such precipitates are generated due to heat at the contact point between the lip 28 and the first opposing rotating body 18, lubricant leakage can easily occur because the precipitates are trapped between them. In this respect, according to this embodiment, as described above, it is advantageous to reduce the contact pressure applied by the lip 28 to the first opposing rotating body 18. Therefore, by reducing this contact pressure, heat generation at the contact point between the lip 28 and the first opposing rotating body 18 is suppressed, and it is beneficial to suppress the generation of precipitates caused by this heat. Furthermore, even when using a lubricant that can generate precipitates due to heat, it is beneficial to suppress lubricant leakage caused by the trapping of these precipitates.

[0058] In addition, the type of lubricant is not particularly limited, and it may not contain any of the above-mentioned elements.

[0059] (Third Embodiment) Next, another embodiment will be described. In subsequent embodiments (including the second embodiment), for the constituent elements described in the first embodiment, the constituent elements not described below can be applied in the same way as in the first embodiment.

[0060] refer to Figure 4 and Figure 5 The lip 28 of the sealing member 10 has a contact area 32, which includes all contact portions between the lip 28 and the first opposing rotating body 18. The contact area 32 is provided within an axial range of all contact portions between the lip 28 and the first opposing rotating body 18, from an inner end position located axially inward to an outer end position located axially outward. Within this axial range, the contact area 32 is located on a first side surface 28c of the lip 28.

[0061] At least one groove 34 is provided in the contact area 32. In this embodiment, the contact area 32 has multiple (specifically three) grooves 34, but the number is not particularly limited; it can be one, two, or more than four. A lubricant such as grease (not shown) is applied to the contact area 32. The groove 34 functions as a lubricant storage section for accumulating this lubricant. This lubricant can be the same as or different from the lubricant sealed within the internal space 22.

[0062] The effects related to the above features will be explained. A lubricating film is formed by lubricant at the contact area between the lip 28 and the first opposing rotating body 18. When the lubricating film ruptures at this contact area, resulting in insufficient lubrication, lubricant leakage is likely to occur. In this regard, a groove 34 is provided in the contact area 32 of the lip 28 in this embodiment. Therefore, by using the groove 34 of the lip 28 as a lubricant storage area, insufficient lubrication at the contact area between the lip 28 and the first opposing rotating body 18 can be suppressed. Furthermore, it is beneficial to suppress lubricant leakage caused by insufficient lubrication.

[0063] According to this embodiment, foreign matter passing between the lip 28 of the sealing member 10 and the first opposing rotating body 18 can be captured in the groove 34. As a result, the biting of foreign matter (especially grinding powder, described later) between the contact area between the lip 28 and the first opposing rotating body 18 and the first opposing rotating body 18 can be suppressed, which helps to suppress lubricant leakage caused by such biting.

[0064] When the starting frequency of the power transmission device 14 is high, or when it operates alternately in both directions, the sliding speed of the lip 28 of the sealing member 10 relative to the first opposing rotating body 18 slows down or becomes zero, easily leading to a boundary lubrication state where insufficient lubrication is likely to occur. According to this embodiment, even in the case where such insufficient lubrication is likely to occur, the groove 34 of the lip 28 can be used as a lubricant storage section, which helps to suppress lubricant leakage caused by insufficient lubrication.

[0065] In addition, the power transmission device 14 of this embodiment also includes the constituent elements described in (A) to (F) above, thereby obtaining the effects corresponding to the description.

[0066] Furthermore, when the groove 34 is provided on the lip 28 as in this embodiment, a lubricant with a consistency grade of 2 to 6 can be applied to the contact area 32 of the lip 28. Hard lubricants with consistency grades of 2 to 6 have poor compliance and are prone to insufficient lubrication. According to this embodiment, even when using such a lubricant that is prone to insufficient lubrication, by using the groove 34 of the lip 28 as a lubricant reservoir, it is beneficial to suppress lubricant leakage caused by insufficient lubrication.

[0067] refer to Figure 5When the lip 28 is in an undeformed state, at least a portion of at least one groove 34 may be located radially closer to the first relative rotating body 18 than the lip contact surface 18a of the first relative rotating body 18. In this embodiment, the entire at least one groove 34 is located radially closer to the first relative rotating body 18 than the lip contact surface 18a of the first relative rotating body 18. When this condition is met, at least two grooves 34 may be located radially closer to the first relative rotating body 18 than the lip contact surface 18a of the first relative rotating body 18. Thus, compared to the case where this condition is not met, the bending deformation of the lip 28 can be increased when the lip 28 is in a deformed state. Furthermore, the overall contact length L0 of the lip 28 can be easily increased, thereby reducing the contact pressure of the lip 28, which is particularly beneficial for suppressing the rise in internal pressure of the internal space 22 caused by pumping force.

[0068] Next, the details of the power transmission device 14 will be described. Here, the power transmission device 14 of embodiments 4 to 7 will be described. After describing the features related to the power transmission device 14 of these embodiments, the features related to the sealing member 10 described above will be described. Furthermore, the description of the power transmission device 14 of these embodiments can also be applied to the power transmission devices 14 of embodiments 1 to 3.

[0069] (Fourth Embodiment) Reference Figure 6 The power transmission device 14 in this embodiment only includes a speed reducer 12. The speed reducer 12 can reduce the input rotation and output the rotation, thereby driving a driven body (not shown). Rotation is input to the speed reducer 12 from a prime mover (not shown) such as a motor or engine. For example, the driven body is 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) conveying equipment such as conveyors, and (4) vehicles.

[0070] The reducer 12 includes: a reduction mechanism 42; a reducer housing 44, in which the reduction mechanism 42 is disposed; and an input-opposite side component 46, at least a portion of which is disposed on the axial input-opposite side of the reduction mechanism 42 and is capable of rotating relative to the reducer housing 44 about the rotation center line Ca.

[0071] The speed reducer 12 of this embodiment uses a flexural meshing speed reduction mechanism as the speed reduction mechanism 42. The speed reducer 12 using this mechanism includes: a vibrating body shaft 50 having a vibrating body 48; a flexible gear 52, which is flexed and deformed by the vibrating body 48; and meshing gears 54A and 54B that mesh with the flexible gear 52. In this embodiment, the vibrating body shaft 50 functions as an input component that directly or indirectly inputs rotation from the outside. The flexible gear 52 and the meshing gears 54A and 54B function as the speed reduction mechanism 42, which reduces the rotation input from the input component. One of the flexible gear 52 and the meshing gears 54A and 54B is an external gear, and the other is an internal gear. Here, an example where the flexible gear 52 is an external gear and the meshing gears 54A and 54B are internal gears will be described. The input-opposite component 46 of this embodiment functions as an output component, which outputs the rotation reduced by the speed reduction mechanism 42 and outputs it to the driven body. The output component can also replace the input-opposite component 46 as the gearbox housing 44.

[0072] In addition to the vibrator 48, the starting shaft 50 also includes shaft portions 58 disposed on both axial sides of the vibrator 48. The cross-sectional shape of the outer periphery of the vibrator 48 is elliptical. The cross-sectional shape of the outer periphery of the shaft portion 58 is circular. Here, the cross-sectional shape refers to the shape of the cross-section orthogonal to the axial direction of the vibrator 48. The term "ellipse" here is not limited to an ellipse in a strictly geometric sense, but also includes an approximate ellipse.

[0073] The flexible gear 52 is a cylindrical component that is flexible enough to be flexibly deformed by the vibrator 48 via the vibrator bearing 60. The meshing gears 54A and 54B have rigidity that does not flex or deform with the rotation of the vibrator 48. In this embodiment, the meshing gears 54A and 54B comprise: a first meshing gear 54A that meshes with the teeth of the input side portion of the flexible gear 52; and a second meshing gear 54B that meshes with the teeth of the input-opposite side portion of the flexible gear 52. The first meshing gear 54A has a different number of teeth (e.g., 102) than the flexible gear 52 (e.g., 100), and the second meshing gear 54B has the same number of teeth as the flexible gear 52.

[0074] In this embodiment, the reducer housing 44 also serves as the first meshing gear 54A. The reducer housing 44 in this embodiment is composed of multiple housing components connected by bolts or the like. A bearing 62 is disposed between the reducer housing 44 and the shaft portion 58 of the vibrator shaft 50. In this embodiment, the input-opposite side component 46 also serves as the second meshing gear 54B. A bearing 64 is disposed between the input-opposite side component 46 and the shaft portion 58 of the vibrator shaft 50. The input-opposite side component 46 in this embodiment is composed of multiple components connected by bolts or the like. A main bearing 66 is disposed between the reducer housing 44 and the input-opposite side component 46.

[0075] An example of the operation of the power transmission device 14 according to this embodiment will be described. In this embodiment, if the vibrating body shaft 50, which serves as the input component, rotates, the flexible gear 52 flexes and deforms into an elliptical shape that matches the shape of the vibrating body 48 of the vibrating body shaft 50. Thus, if the flexible gear 52 flexes and deforms, the meshing position of the flexible gear 52 and the meshing gears 54A and 54B changes in the rotation direction of the vibrating body 48. At this time, the meshing position of the flexible gear 52 with different numbers of teeth and the first meshing gear 54A shifts circumferentially with each revolution. As a result, in this embodiment, the flexible gear 52 rotates, and this rotational component is output by the input-opposite component 46, which serves as the output component. In this embodiment, the flexible gear 52 and the second meshing gear 54B have the same number of teeth and are therefore synchronized. The rotational component of the flexible gear 52 is output by the input-opposite component 46, which is the output component, through the second meshing gear 54B, which is synchronized with the flexible gear 52. At this time, the output rotation is reduced to a reduction ratio corresponding to the tooth number difference between the flexible gear 52 and the first meshing gear 54A, in response to the input rotation to the vibrator shaft 50.

[0076] (Fifth Embodiment) Reference Figure 7 . Figures 7-9 The reducer 12 in this embodiment uses an eccentric oscillating type reducer mechanism as the reducer mechanism 42. In particular, the reducer 12 in this embodiment uses a center crank type eccentric oscillating type reducer mechanism. The reducer 12 using these includes: a crankshaft 72 having an eccentric portion 70; an oscillating gear 74 that oscillates through the eccentric portion 70; and a meshing gear 76 that meshes with the oscillating gear 74. In this embodiment, the crankshaft 72 functions as an input component. The oscillating gear 74 and the meshing gear 76 function as the reducer mechanism 42. One of the oscillating gear 74 and the meshing gear 76 is an external gear, and the other is an internal gear. Here, an example where the oscillating gear 74 is an external gear and the meshing gear 76 is an internal gear will be described. The input-reverse component 46 in this embodiment functions as an output component.

[0077] The input-opposite side component 46 of this embodiment includes: a flange portion 46a, which is disposed on the input-opposite side relative to the reduction mechanism 42; and a shaft portion 46b, which is disposed on the input-opposite side relative to the flange portion 46a and has a diameter smaller than that of the flange portion 46a. A collar 78, which is integrally rotatable with the shaft portion 46b, is mounted on the shaft portion 46b in this embodiment.

[0078] In this embodiment, the crankshaft 72 is disposed on the rotation center line C72. The crankshaft 72 has at least one (in this case, two) eccentric portion 70. The eccentric portion 70 is circular with respect to the rotation center line C72 of the crankshaft 72. In this embodiment, the eccentric portion 70 is separately disposed from another part of the crankshaft 72, but as Figure 8 , Figure 9 In the same manner, it can also be integrated with another part of the crankshaft 72 using the same components. The oscillating gear 74 is configured to correspond to the eccentric portion 70 and is supported on the corresponding eccentric portion 70 via the eccentric bearing 80.

[0079] In this embodiment, the meshing gear 76 is disposed on the inner periphery of the reducer housing 44. The meshing gear 76 includes a gear body 76a, which is also served by the reducer housing 44, and teeth 76b disposed on the gear body 76a. In this embodiment, the teeth 76b are formed by a roller 76d, which is disposed on a support pin 76c supported on the gear body 76s and is rotatable. Otherwise, the meshing gear 76... Figure 8 In some embodiments, the toothed portion 76b is formed by the support pin 76c, and the roller 76d may not be present. Alternatively, as... Figure 9 As in the previous embodiment, the teeth 76b of the meshing gear 76 can also be integrally formed from the same component as the gear body 76a.

[0080] A pin 82, which passes through the oscillating gear 74, protrudes from the input-opposite-side component 46 of this embodiment. The pin 82 contacts the oscillating gear 74 directly or indirectly, thereby enabling the rotational component of the oscillating gear 74 to be synchronized with the input-opposite-side component 46.

[0081] An example of the operation of the power transmission device 14 according to this embodiment will be described. When the crankshaft 72, which serves as the input component, rotates, the eccentric portion 70 causes the oscillating gear 74 to oscillate. As the oscillating gear 74 oscillates, the meshing position of the oscillating gear 74 and the meshing gear 76 changes circumferentially. Thus, each time the crankshaft 72 rotates once, the oscillating gear 74 rotates on its own axis, and this rotational component is output via the pin 82 from the input-opposite component 46, which serves as the output component. At this time, relative to the input rotation input to the crankshaft 72, the output rotation is reduced to a reduction ratio corresponding to the tooth difference between the oscillating gear 74 and the meshing gear 76.

[0082] (Sixth Embodiment) Reference Figure 8 In this embodiment, the power transmission device 14 includes, in addition to the reducer 12, a prime mover 90, an adapter 92 connecting the prime mover 90 and the reducer 12, and a disc-shaped driven body 94 driven by the reducer 12. Thus, the power transmission device 14 may only include the reducer 12, or it may include one or more of the prime mover 90, adapter 92, and driven body 94 in addition to the reducer 12.

[0083] In this embodiment, the prime mover 90 is a motor. The prime mover 90 includes a prime mover housing 96 and a prime mover shaft 98 for outputting the rotation generated inside the prime mover 90. The prime mover housing 96 is connected to the gearbox housing 44 via an adapter 92.

[0084] and Figure 7 Similarly, as the reduction mechanism 42, the reducer 12 of this embodiment uses a center crank-type eccentric oscillating reduction mechanism. The crankshaft 72 of the reducer 12 of this embodiment is connected to the driving shaft 98 by a key or the like so that it can rotate integrally. The crankshaft 72 of this embodiment has three eccentric portions 70. The reducer 12 of this embodiment has a wheel carrier 100 disposed on the input side relative to the reduction mechanism 42. The wheel carrier 100 is integrally connected to the input-opposite-side component 46 by a pin 82. The main bearing 66 is disposed between the reducer housing 44 and the input-opposite-side component 46, and also between the reducer housing 44 and the wheel carrier 100.

[0085] (Seventh Embodiment) Reference Figure 9 .and Figure 8 Similarly, in addition to the reducer 12, the power transmission device 14 of this embodiment also includes a prime mover 90, an adapter 92, and a driven body 94.

[0086] In this embodiment, the reducer 12, serving as the reduction mechanism 42, utilizes a distribution-type eccentric oscillating reduction mechanism. The reducer 12 employing this reduction mechanism 42 has multiple crankshafts 72 positioned radially offset from the rotation center line Ca (only a single crankshaft is shown here). Each of the multiple crankshafts 72 is equipped with a crankshaft gear 102, which is capable of rotating integrally. The crankshaft gear 102 meshes with an input pinion 106 provided on a relay shaft 104. The relay shaft 104 is connected to the prime mover shaft 98 via a key or similar means, enabling integral rotation. The multiple crankshafts 72 receive rotational input from the prime mover shaft 98 via the relay shaft 104 and the crankshaft gears 102.

[0087] Next, the features associated with the sealing member 10 in the power transmission device 14 described in embodiments 4 to 7 will be explained. Hereinafter, reference will be made primarily to... Figure 6The following explanation is provided. In each embodiment, there are multiple sealing components 10 and multiple sets of paired opposing rotating bodies 16. When distinguishing these multiple sealing components 10 and multiple sets of paired opposing rotating bodies 16, the end of the symbols is marked with "-A", "-B", or "-C".

[0088] The reduction mechanism 42 in each embodiment is composed of a gear mechanism 110. The gear mechanism 110 includes a gear set 112 composed of a plurality of meshing gears. Figure 6 The gear set 112 in the embodiment consists of a flexible gear 52 and meshing gears 54A and 54B. Figures 7-9 The gear set 112 in the embodiment consists of an oscillating gear 74 and a meshing gear 76. For example, the gear set 112 is made of a metal material such as an iron-based material or an aluminum-based material, but it may also be made of a resin-based material.

[0089] The power transmission device 14 includes at least one pair of opposing rotating bodies 16-A and 16-B, which rotate relative to each other around the rotation center line Ca during operation of the power transmission device 14. Here, "operation of the power transmission device 14" refers to the moment when each power transmission element of the power transmission device 14 is working. For example, the power transmission elements here refer to the input component, a part of the reduction mechanism 42 (flexible gear 52, oscillating gear 74, etc.), and the output component, etc.

[0090] exist Figures 6-9 In this embodiment, at least one set of paired relative rotating bodies 16-A, 16-B includes: a pair of high-speed relative rotating bodies 16-A rotating relative to each other at a first relative rotational speed; and a pair of low-speed relative rotating bodies 16-B rotating relative to each other at a second relative rotational speed slower than the first relative rotational speed. One of the paired high-speed relative rotating bodies 16-A is constituted by a fixed body 114 fixed to an external component (not shown) supporting the power transmission device 14, and the other is constituted by a high-speed rotating body 116A rotating relative to the fixed body 114. One of the paired low-speed relative rotating bodies 16-B is constituted by the fixed body 114, and the other is constituted by a low-speed rotating body 116B rotating relative to the fixed body 114 at a lower speed than the high-speed rotating body 116A. Thus, one of the paired relative rotating bodies 16-A, 16-B is constituted by rotating bodies 116A, 116B. One of the fixed body 114 and the high-speed rotating body 116A becomes the first relative rotating body 18 mentioned above, and the other becomes the second relative rotating body 20. Furthermore, one of the fixed body 114 and the low-speed rotating body 116B becomes the first relative rotating body 18 mentioned above, and the other becomes the second relative rotating body 20.

[0091] exist Figure 6In one embodiment, an example is shown where the fixed body 114 is a reducer housing 44, the high-speed rotating body 116A is a vibrator shaft 50, and the low-speed rotating body 116B is an input-opposite side component 46. Furthermore, in... Figure 7 In this embodiment, a fixed body 114 is shown as a gearbox housing 44, a high-speed rotating body 116A is a crankshaft 72, and a low-speed rotating body 116B is an example of a combination of an input-opposite side component 46 and a collar 78. Figure 8 In one embodiment, the fixed body 114 is shown as a combination of a reducer housing 44, an adapter 92, and a prime mover housing 96; the high-speed rotating body 116A is a combination of a crankshaft 72 and a prime mover shaft 98; and the low-speed rotating body 116B is an example of a combination of an input-opposite side component 46 and a driven body 94. Figure 9 In one embodiment, the fixed body 114 is shown as a combination of a reducer housing 44, an adapter 92, and a prime mover housing 96; the high-speed rotating body 116A is a combination of a relay shaft 104 and a prime mover shaft 98; and the low-speed rotating body 116B is an example of a combination of an input-opposite side component 46 and a driven body 94. Figures 6-9 In the embodiments shown, an example is presented where the high-speed rotating body 116A, the low-speed rotating body 116B are the first relative rotating body 18, and the fixed body 114 is the second relative rotating body 20. Thus, the specific examples of the fixed body 114, the high-speed rotating body 116A, and the low-speed rotating body 116B are not particularly limited.

[0092] exist Figures 6-8 In one embodiment, the paired high-speed relative rotating bodies 16-A include a reducer rotating shaft 118, which serves as a reducer 12 and rotates during the operation of the power transmission device 14. For example, this reducer rotating shaft 118 is designed to... Figure 6 The flexible gear 52 flexurally deforms the vibrating shaft 50, or makes it as described in the embodiment. Figure 7 , Figure 8 Any one of the crankshafts 72 that oscillates with the oscillating gear 74 as in the embodiment.

[0093] like Figures 6-9 As in the embodiment described, sealing members 10-A to 10-C may include a first sealing member 10-A disposed between at least a pair of high-speed relative rotating bodies 16-A. Alternatively, sealing members 10-A to 10-C may also include a second sealing member 10-B disposed between a pair of low-speed relative rotating bodies 16-B. In addition, as... Figure 6In the same manner, sealing components 10-A to 10-C may also include a third sealing component 10-C disposed between a high-speed rotating body 116A, which is one of a pair of high-speed relative rotating bodies 16-A, and a low-speed rotating body 116B, which is one of a pair of low-speed relative rotating bodies 16-B. The features described in the first to third embodiments can be applied to these sealing components 10-A to 10-C.

[0094] A speed reduction mechanism 42 is provided in the internal space 22 of the power transmission device 14, which is sealed by sealing components 10-A to 10-C. Figures 6-9 The internal space 22 of each embodiment is formed in a position at least surrounded by the fixed body 114 (reducer housing 44), the high-speed rotating body 116A, and the low-speed rotating body 116B (input-opposite-side component 46). Figures 6-9 In this embodiment, at least one of the reducer housing 44 and the input-opposite component 46 also serves as a component of the reduction mechanism 42 (e.g., meshing gears 54A, 54B, and 76). That is, the space forming body that creates the internal space 22 also serves as a component of the reduction mechanism 42. In this case, when the condition for the reduction mechanism 42 to be disposed in the internal space 22 is met, at least one component of the reduction mechanism 42 that is different from the component of the space forming body (e.g., flexible gears 52 and 74) can be disposed in the internal space 22.

[0095] A lubricant (not shown) is sealed in the internal space 22. The lubricant is used to lubricate the sliding or rolling contact points between the constituent elements of the reduction mechanism 42. For example, here, the sliding or rolling contact points refer to the meshing points of the multiple gears constituting the gear set 112. Figures 6-9 The lubricant used in this embodiment is grease, but its specific form is not particularly limited; for example, it could also be lubricating oil. The internal space 22 is sealed by at least one sealing member 10. When sealing the internal space 22, in addition to using the sealing member 10, sealing members such as oil seals, which are different from the sealing member 10, can also be used simultaneously. The number of sealing members 10 used to seal the internal space 22 is not particularly limited, nor is the number and type of sealing members particularly limited; they can be appropriately changed depending on the type of power transmission device 14.

[0096] The effects of the sealing component 10 related to the features of the power transmission device 14 will be explained.

[0097] Consider the case where the internal space 22 is sealed using pumping force and a spring-loaded sealing member. The inventors of this application have newly recognized that the pumping force is more easily increased at the location of the first sealing member 10-A compared to the location of the second sealing member 10-B, thereby easily leading to lubricant leakage. This is believed to be because the sliding speed of the first sealing member 10-A is faster than that of the first relative rotating body 18 (high-speed rotating body 116A), which is one of a pair of low-speed relative rotating bodies 16-B, compared to the sliding speed of the second sealing member 10-B relative to the first relative rotating body 18 (low-speed rotating body 116B), which is one of a pair of low-speed relative rotating bodies 16-B. In this respect, according to this embodiment, the aforementioned sealing member 10-A, which is advantageous in suppressing lubricant leakage caused by pumping force, is used between the pairs of high-speed relative rotating bodies 16-A. Therefore, by significantly reducing the pumping force at the location where the first sealing component 10-A is positioned where the pumping force is likely to increase, it is beneficial to suppress lubricant leakage caused by the pumping force.

[0098] The sealing member 10-A of this embodiment, by satisfying the aforementioned length condition, is advantageous in extending the overall contact length L0 between the lip 28 and the first relative rotating body 18, as described above. Therefore, by extending this contact length L0, even if a foreign object is embedded between the lip 28 and the first relative rotating body 18, it is easy to maintain the contact between the lip 28 and the first relative rotating body 18 at a position offset axially relative to the embedding position of the foreign object. Therefore, it is beneficial to suppress lubricant leakage caused by foreign object embedding. In particular, when the reduction mechanism 42 is constituted by a gear mechanism 110, abrasive particles are easily generated in the internal space 22 of the power transmission device 14 due to the meshing of the gears constituting the gear set 112. According to this embodiment, it is effective in that, in a power transmission device 14 that uses a gear mechanism 110 that easily generates abrasive particles, lubricant leakage caused by the embedding of abrasive particles can be suppressed.

[0099] The rotating body 116A, which has a reducer rotating shaft 118, may sometimes bear radial loads generated inside the reducer 12. This may be, for example, (1) when the reducer rotating shaft 118 is a vibrator shaft 50, or (2) when the reducer rotating shaft 118 is a crankshaft 72. In case (1), a radial load is input from the flexible gear 52 to the vibrator shaft 50 during the process of the vibrator 48 of the vibrator shaft 50 flexing and deforming the flexible gear 52. In case (2), a radial load is input from the oscillating gear 74 to the eccentric portion 70 of the crankshaft 72 during the process of oscillating the oscillating gear 74.

[0100] The inventors of this application have newly recognized that when the rotating body 116A is subjected to a radial load, axial misalignment of the rotating body 116A is easily induced, thereby easily causing lubricant leakage at the configuration position of the sealing member 10-A located between the pair of opposing rotating bodies 16-A containing the rotating body 116A. This is believed to be because uneven wear occurs on the lip 28 of the sealing member 10-A due to the axial misalignment of the rotating body 116A, thereby easily compromising the sealing performance of the sealing member 10-A. Here, axial misalignment refers to the radial displacement of the rotation center line of the rotating body 116A, or the tilting displacement of the rotation center line.

[0101] In this embodiment, the sealing member 10-A, by satisfying the aforementioned length condition, is advantageous in reducing the contact pressure of the lip 28, as described above. Therefore, by reducing this contact pressure, uneven wear in the lip 28 caused by axial misalignment of the rotating body 116A is less likely to occur, which helps maintain the sealing performance of the sealing member 10-A. Thus, even when the rotating body 116A is subjected to radial loads that easily induce axial misalignment, it is beneficial to suppress the resulting lubricant leakage.

[0102] In addition, the specific example of the reducer rotating shaft 118 is not particularly limited, and it can also be a reducer rotating shaft other than the vibrator shaft 50 and the crankshaft 72.

[0103] (Eighth Embodiment) Reference Figure 10 The power transmission device 14 in this embodiment and Figure 6 Similarly, the implementation method only includes a speed reducer 12. The structure of the speed reducer 12 is the same as... Figure 6 The method is the same, so its explanation is omitted.

[0104] The paired opposing rotating bodies 16 include a rotating body 134, which transmits torque between itself and another rotating body 132 via a torque transmission mechanism 130. For example, the rotating body 134 in this embodiment has a vibrating shaft 50 as an input component, but it may also have a crankshaft 72 or the like. The other rotating body 132 in this embodiment has a driving shaft 98, but it may also not have a driving shaft 98.

[0105] In this embodiment, the rotating body 134 bears a radial load when transmitting torque between itself and another rotating body 132. Alternatively, the torque transmission mechanism 130 is configured to apply a radial load to the rotating body 134 when transmitting torque between itself and the other rotating body 132. Thus, when applying a radial load to the rotating body 134, the torque transmission mechanism 130 of this embodiment uses a drive belt 136. Specifically, the torque transmission mechanism 130 of this embodiment includes: a first pulley 138 capable of rotating integrally with the other rotating body 132; a second pulley 140 capable of rotating integrally with the rotating body 134; and a drive belt 136 suspended on the first pulley 138 and the second pulley 140. The drive belt 136 transmits torque between the first pulley 138 and the second pulley 140.

[0106] The rotating body 134, which is in contact with the sealing member 10 of this embodiment, bears a radial load when transmitting torque between itself and another rotating body 132. At this time, as described above, axial misalignment of the rotating body 134 is likely to occur, which can easily lead to lubricant leakage at the location of the sealing member 10 between the pair of opposing rotating bodies 16 containing the rotating body 134.

[0107] In this respect, the sealing member 10 of this embodiment, by satisfying the aforementioned length condition, is advantageous in reducing the contact pressure exerted by the lip 28 on the first relative rotating body 18, as described above. Therefore, by reducing this contact pressure, uneven wear in the lip 28 caused by axial misalignment of the rotating body 134 is less likely to occur, which is advantageous in maintaining the sealing performance of the sealing member 10. Therefore, even when the rotating body 134 is subjected to radial loads that easily induce axial misalignment, it is advantageous to suppress the resulting lubricant leakage.

[0108] Thus, when the rotating body 134 is subjected to a radial load, uneven wear may occur in the sealing member 10 that contacts the rotating body 134, easily leading to lubricant leakage. For example, it is conceivable that the rotating body 134 is subjected to a radial load when a power transmission device 14 is assembled at the joint of a robot. In this case, by employing the structure of the sealing member 10 described above, it is advantageous to suppress lubricant leakage caused by axial misalignment of the rotating body 134.

[0109] Furthermore, in cases where it is easy to cause axial misalignment of the rotating body 134, it is preferable to... Figure 4 As in the embodiment, a groove 34 is provided in the contact area 32 of the lip 28. By utilizing the groove 34 as a lubricant accumulation section, the amount of lubricant present between the first relative rotating body 18 and the lip 28 can be increased. As a result, uneven wear caused by axial misalignment of the rotating body 134 can be suppressed, which helps to suppress lubricant leakage caused by such axial misalignment.

[0110] The specific example of the torque transmission mechanism 130 is not particularly limited in order to apply a radial load to the rotating body 134. For example, to achieve this purpose, the torque transmission mechanism 130 may also be composed of gear assemblies such as bevel gear assemblies or helical gear sets that mesh with each other. Furthermore, the rotating body 134 may not bear a radial load when transmitting torque between itself and another rotating body 132.

[0111] Next, variations of the above-mentioned constituent elements will be described.

[0112] The specific example of the reduction mechanism 42 used in the reducer 12 is not particularly limited. When the reduction mechanism 42 is a gear mechanism, in addition to eccentric oscillating type reduction mechanisms and flexural meshing type reduction mechanisms, it can also be, for example, a simple planetary gear mechanism, an orthogonal axis gear mechanism, a parallel axis gear mechanism, etc. Furthermore, the specific type of flexural meshing type reduction mechanism is not particularly limited, except that it can be... Figure 6 Besides the cylindrical shape as described in the implementation, it can also be a top hat shape, a cup shape, etc. The specific type of the eccentric oscillating reduction mechanism is not particularly limited, and the aforementioned center crank type, distribution type, etc., can also be used. Furthermore, the reduction mechanism 42 can be a gear mechanism, or a friction transmission mechanism (traction drive), etc.

[0113] The sealing member 10 employing the features of the present invention only needs to be disposed between at least one set of paired opposing rotating bodies 16, and does not necessarily need to be disposed between multiple sets of paired opposing rotating bodies 16. In this case, the sealing member 10 employing the features of the present invention can be disposed between one set of paired opposing rotating bodies 16, and other sealing members such as oil seals (e.g., spring-loaded sealing members) that do not employ the features of the present invention can be disposed between other pairs of paired opposing rotating bodies 16. Alternatively, the sealing member 10 employing the features of the present invention can be disposed only between either a pair of high-speed opposing rotating bodies 16-A or a pair of low-speed opposing rotating bodies 16-B.

[0114] The components described in the above embodiments are examples. The abstracted technical concepts should not be interpreted as limited to the contents of this specification. The components described in the embodiments can be modified, added to, or deleted in various design changes. Such design changes are emphasized by the terms "this embodiment" or "implementation". However, design changes are allowed even without such annotations. The shaded lines on the cross-sections of the drawings are not intended to limit the material of the objects to which the shaded lines are drawn. The structures and values ​​mentioned in the embodiments and variations include those that can be considered the same when considering manufacturing errors, etc. Any combination of the above components is also valid. For example, any description of another embodiment can be combined with an embodiment, or any description of an embodiment and its variations can be combined with a variation. In the description of this specification, a component consisting of a single part can also be consisting of multiple parts. Similarly, a component made of multiple parts can also be consisting of a single part.

Claims

1. A power transmission device comprising a speed reducer, the power transmission device comprising: Pairs of relatively rotating solids, rotating relative to each other; and A sealing component, disposed between the pair of opposing rotating bodies, is used to seal the internal space of the power transmission device. The sealing member has a lip that contacts one of the paired opposing rotating bodies, namely the first opposing rotating body. No spring component is installed on the lip to press against the first relative rotating body. The lip has a corner portion, which is positioned radially opposite to the first relative rotating body. The axial contact length between the lip and the first relative rotating body on the side of the inner space that is more axially opposite to the corner is longer than the axial contact length between the lip and the first relative rotating body on the side of the inner space that is more axially opposite to the corner.

2. The power transmission device according to claim 1, wherein, The lip has a front end face that is continuous with the corner and a side face that is continuous with the corner. In the lip, only the front end face and the side face are in contact with the first relative rotating body.

3. The power transmission device according to claim 1, wherein, The lip has a front end face that is continuous with the corner portion. The axial contact length between the lip and the first relative rotating body is longer than the axial length of the front end face when the lip is in an undeformed state.

4. The power transmission device according to claim 1, wherein, The axial contact length between the lip and the first relative rotating body is longer than the minimum thickness of the lip at the contact point between the lip and the first relative rotating body.

5. The power transmission device according to claim 1, wherein, The lip has a contact area, which includes all the contact portions between the lip and the first relative rotating body. At least one groove is provided in the contact area.

6. The power transmission device according to claim 1, wherein, The paired relative rotating bodies include: a pair of high-speed relative rotating bodies rotating relative to each other at a first relative rotational speed; and a pair of low-speed relative rotating bodies rotating relative to each other at a second relative rotational speed that is slower than the first relative rotational speed. The sealing component is disposed at least between the pair of high-speed relative rotating bodies.

7. The power transmission device according to claim 1, wherein, The speed reducer has a speed reduction mechanism composed of gears.

8. The power transmission device according to claim 1, wherein, A lubricant is sealed within the internal space. The lubricant contains at least one of the following elements: Mo, S, Ca, Zn, Ba, Mg, P, C, B, and W.

9. The power transmission device according to claim 1, wherein, The paired opposing rotating bodies include a rotating body, which transmits torque with other rotating bodies via a torque transmission mechanism. The rotating body bears radial loads when transmitting torque between itself and the other rotating bodies.

10. The power transmission device according to claim 1, wherein, The paired opposing rotating bodies include a rotating body equipped with a reducer rotating shaft. The reducer's rotating shaft is either a crankshaft that causes the oscillating gear to oscillate, or a vibrating shaft that causes the flexible gear to flex and deform.

Images