sealing structure

Abstract

To provide a technology which can suppress the leakage of a sealing material when the inner pressure of a casing becomes higher due to a rise of a temperature.SOLUTION: In a sealing structure having a casing and a seal member 58A for sealing an internal space of the casing, the seal member 58A is arranged in an opening hole 52A formed at an inside member which is arranged at the casing 18, or inside the casing 18, the sealing member 58A comprises a core material 74 and an elastic material 76 which is integrated with the core material 74, the core material 74 is constituted by combining a low-expansion coefficient member 100 and a high-expansion coefficient member 102 which are different from each other in thermal expansion coefficients, and the low-expansion coefficient member 100 and the high-expansion coefficient member 102 are arranged so that a pressing force of the seal member 58A with respect to at least either of the casing 18 and the inside member is increased accompanied by a rise of a temperature.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This disclosure relates to a sealing structure.

Background Art

[0002] Patent Document 1 discloses a sealing structure including a casing, a carrier disposed in a first opening provided in the casing, and a sealing member for sealing the internal space of the casing. Patent Document 1 discloses, as the sealing member, an oil seal that closes the gap between the carrier and the casing, and a seal cap that closes a second opening provided in the carrier.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the internal pressure of the internal space of the casing increases due to an increase in temperature, the encapsulant enclosed in the internal space is likely to leak from the location where the sealing member is disposed. The inventor of the present application has obtained the recognition that there is room for improvement in the prior art in relation to such a problem.

[0005] One object of this disclosure is to provide a technique capable of suppressing leakage of the encapsulant when the internal pressure of the casing increases due to an increase in temperature.

Means for Solving the Problems

[0006] The seal structure of the present disclosure comprises a casing and a seal member for sealing the internal space of the casing, wherein the seal member is disposed in an opening provided in the casing or an inner member disposed inside the casing, and the seal member comprises a core material and an elastic material integrated with the core material, wherein the core material is composed of a low-expansion member and a high-expansion member having different coefficients of thermal expansion, and the low-expansion member and the high-expansion member are arranged such that the pressing force of the seal member against at least one of the casing and the inner member increases with increasing temperature. [Effects of the Invention]

[0007] According to this disclosure, leakage of the sealing material can be suppressed when the internal pressure of the casing increases due to a rise in temperature. [Brief explanation of the drawing]

[0008] [Figure 1] This is a side cross-sectional view of the power transmission device of the first embodiment. [Figure 2] This is a cross-sectional view of the seal structure of the first embodiment. [Figure 3] This is an explanatory diagram illustrating the operation of the seal structure of the first embodiment. [Figure 4] This is a cross-sectional view of the seal structure of the second embodiment. [Figure 5] This is a cross-sectional view of the seal structure of the third embodiment. [Figure 6] This is an explanatory diagram illustrating the operation of the seal structure of the third embodiment. [Figure 7] This is a cross-sectional view of the seal structure of the fourth embodiment. [Figure 8] This is a cross-sectional view of the seal structure of the fifth embodiment. [Figure 9] This is a cross-sectional view of a deformed seal structure. [Figure 10] This is a cross-sectional view of the seal structure of the sixth embodiment. [Modes for carrying out the invention]

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

[0010] (First Embodiment) Refer to Figure 1. Before describing the seal structure 50 of this embodiment, the mechanical device 10 in which the seal structure 50 is used will be described. The mechanical device 10 of this embodiment is a gear device in which a gear mechanism 14 is used. This mechanical device 10 comprises an input member 12, a gear mechanism 14 that changes the speed of rotation of the input member 12, and an output member 16 that outputs the output rotation transmitted from the gear mechanism 14 to a driven device. In addition, the mechanical device 10 comprises a casing 18 that houses the gear mechanism 14, and carriers 20A and 20B that are arranged axially laterally with respect to the external gears 22 that constitute the gear mechanism 14.

[0011] The mechanical device 10 of this embodiment is an eccentric oscillating gear device comprising an external gear 22 and an internal gear 24 that mesh with each other as a gear mechanism 14. This type of gear device can transmit output rotation to the output member 16 by oscillating one of the external gear 22 and the internal gear 24 (in this case, the external gear 22) by a crankshaft 28. In this embodiment, an example in which the carrier 20A is the output member 16 is described, but the casing 18 may also be the output member 16.

[0012] Rotational power is input to the input member 12 from the drive device 26. In this embodiment, the drive device 26 is a motor, but its specific example is not limited and may be a gear motor, engine, etc. In this embodiment, the input member 12 is a crankshaft 28. The crankshaft 28 is provided with at least one (two in this case) eccentric body 30 that is eccentric with respect to the rotation center C28 of the crankshaft 28. The eccentric body 30 can oscillate the external gear 22 by rotating around the rotation center C28 of the crankshaft 28.

[0013] The mechanical device 10 of the present embodiment is a sorting type eccentric swing gear device in which a plurality of crankshafts 28 are arranged at positions offset from the center C24 of the internal gear 24. Crankshaft gears 32 are provided on the plurality of crankshafts 28 of the present embodiment, and the rotational power of the drive device 26 is sorted via a common gear 33 meshing with the crankshaft gears 32.

[0014] The external gear 22 is supported so as to be relatively rotatable with respect to the eccentric body 30 of the crankshaft 28 via a gear bearing 34. The internal gear 24 is integrated with the casing 18. Main bearings 36 that connect the casing 18 and the carriers 20A and 20B so as to be relatively rotatable are arranged between the casing 18 and the carriers 20A and 20B.

[0015] The carriers 20A and 20B include a first carrier 20A arranged on the anti-input side with respect to the external gear 22 and a second carrier 20B arranged on the input side with respect to the external gear 22. The carriers 20A and 20B include a central through hole 38 penetrating the centers C20 of the carriers 20A and 20B and an offset through hole 40 penetrating the carriers 20A and 20B at a position offset radially from the centers C20 of the carriers 20A and 20B. The carriers 20A and 20B of the present embodiment can be synchronized with the rotation component of the external gear 22 by the crankshaft 28 that penetrates the external gear 22 and is arranged inside the offset through hole 40.

[0016] The operation of the above mechanical device 10 (gear device) will be described. When the input member 12 rotates due to the rotational power transmitted from the driving force, the gear mechanism 14 operates. When the gear mechanism 14 operates, output rotation is transmitted from the gear mechanism 14 to the output member 16, and the output rotation is output to the driven device.

[0017] When using an eccentric swing type gear device as in this embodiment, when the input member 12 (crankshaft 28) rotates, the external gear 22 swings due to the eccentric body 30 of the crankshaft 28. When the external gear 22 swings, the meshing position between the external gear 22 and the internal gear 24 changes in the circumferential direction. Along with this, every time the crankshaft 28 makes one rotation, the external gear 22 rotates by the difference in the number of teeth between the external gear 22 and the internal gear 24. This rotation component is transmitted as output rotation to the output member 16 (carriers 20A, 20B). In this embodiment, the output rotation decelerated with respect to the rotation of the input member 12 is transmitted to the output member 16.

[0018] Move on to the description of the seal structure 50. The seal structure 50 includes the aforementioned casing 18 in which the first opening hole 52A is formed, an inner member 54 disposed inside the first opening hole 52A of the casing 18, and seal members 58A, 58B for sealing the internal space 56 of the casing 18.

[0019] The internal space 56 formed inside the casing 18 communicates with an external space 60 outside the mechanical device 10 through the first opening hole 52A and a second opening hole 52B (described later). A semi-solid or liquid encapsulant (not shown) is encapsulated in the internal space 56 of the casing 18. The encapsulant is, for example, a lubricant such as grease or lubricating oil used for lubricating the gear mechanism 14. The internal space 56 of this embodiment communicates with the internal spaces of an adapter 62 that connects the casing 18 and the drive device 26 and the drive device 26. Thus, the internal space 56 may communicate with the internal spaces of other members connected to the casing 18, or may not communicate with the internal spaces of other members.

[0020] The inner member 54 rotates relative to the casing 18 during the operation of the mechanical device 10. It can also be said that the mechanical device 10 is a rotating device including the casing 18 and the inner member 54 that rotate relative to each other during operation. The inner member 54 of this embodiment is the carrier 20A. A plurality of second opening holes 52B that allow the internal space 56 and the external space 60 to communicate with each other are formed in the inner member 54. The plurality of second opening holes 52B are constituted by the aforementioned central through hole 38 and the offset through hole 40.

[0021] The sealing members 58A and 58B include a first sealing member 58A disposed in the first opening hole 52A of the casing 18 and a second sealing member 58B disposed in the second opening hole 52B of the inner member 54. The first sealing member 58A is an oil seal that seals the gap between the first opening hole 52A of the casing 18 and the inner member 54, and is disposed between the first opening hole 52A and the inner member 54. The second sealing member 58B is a seal cap that seals the second opening hole 52B by blocking the entire second opening hole 52B of the inner member 54.

[0022] Refer to Figure 2. Here, we will explain the case where the main features of the seal structure 50 of this disclosure (the low-expansion member 100 and the high-expansion member 102, which will be described later) are applied to the first seal member 58A as an example. Hereafter, the direction along the center C58 (see Figure 1) of the opening hole (here, the first opening hole 52A) in which the seal member (here, the first seal member 58A) is placed will be called the axial direction X, and the radial direction and circumferential direction with C58 as the center of the circle will also simply be called the radial direction and circumferential direction.

[0023] The inner circumferential surface of the first opening hole 52A, in which the first sealing member 58A is positioned, and the outer circumferential surface of the inner member 54 are radially opposite each other. The inner circumferential surface of the first opening hole 52A is provided with a fitting surface 70 in which the first sealing member 58A is fixed in a fitted state, and the outer circumferential surface of the inner member 54 is provided with a lip contact surface 72 in which the sealing lip portion 82 (described later) of the first sealing member 58A makes contact.

[0024] The first sealing member 58A comprises a core material 74 and an elastic material 76 integrated with the core material 74. The core material 74 is, for example, a metal ring. The core material 74 is made of, for example, metal, and the elastic material 76 is made of, for example, rubber. The elastic material 76 is integrated with the core material 74 by vulcanization bonding or the like.

[0025] The core material 74 plays a role in ensuring the rigidity of the first sealing member 58A. The core material 74 comprises a cylindrical axially extended portion 78 extending in the axial direction X, and a radially extended portion 80 extending radially from the axially extended portion 78. In this embodiment, the radially extended portion 80 is annular. The radially extended portion 80 extends from the end of the axially extended portion 78 on the external space 60 side to the radially opposite side (inner circumference side) from the mating surface 70. It can also be said that the axially extended portion 78 extends in the axial direction X from the end of the radially extended portion 80 on the radially opposite side (outer circumference side) from the lip contact surface 72.

[0026] The first sealing member 58A is fixed in a fitted state on the mating surface 70 by an interlocking fit. In this embodiment, the first sealing member 58A is fixed with the first covering portion 86 (described later) of the elastic material 76 in contact with the mating surface 70. As a result, the space between the core material 74 and the mating surface 70 is sealed by the first covering portion 86 of the elastic material 76. Alternatively, instead of the elastic material 76, the first sealing member 58A may be fixed with the axially extended portion 78 of the core material 74 in contact with the mating surface 70.

[0027] The elastic material 76 includes a seal lip portion 82 that contacts the lip contact surface 72. The seal lip portion 82 prevents leakage of the sealing material from the internal space 56 to the external space 60 by contacting the lip contact surface 72. The seal lip portion 82 extends axially X toward the internal space 56 from the end of the radially extending portion 80 of the core material 74 that is on the lip contact surface 72 side (in this case, the inner circumference side). The seal lip portion 82 includes a lip end portion 82a that protrudes toward the lip contact surface 72 side and contacts the lip contact surface 72. The seal lip portion 82 slides against the lip contact surface 72 when the casing 18 and the inner member 54 rotate relative to each other during the operation of the machine device 10.

[0028] In addition to the above, the elastic material 76 of this embodiment includes a dust lip portion 84 provided on the external space 60 side of the lip end portion 82a of the seal lip portion 82 and in contact with the lip contact surface 72. The dust lip portion 84 prevents dust from entering the internal space 56 from the external space 60. In addition to the above, the elastic material 76 of this embodiment includes a first covering portion 86 that covers the axially extending portion 78 of the core material 74 and a second covering portion 88 that covers the radially extending portion 80 of the core material 74.

[0029] The first sealing member 58A includes a biasing member 90 attached to the sealing lip portion 82 on the radially opposite side from the lip end portion 82a. The biasing member 90 is, for example, an endlessly continuous circumferential garter spring. The biasing member 90 can bias the sealing lip portion 82 toward the lip contact surface 72 by applying a tightening force that presses the sealing lip portion 82 against the lip contact surface 72.

[0030] Here, the core material 74 comprises a low-expansion member 100 and a high-expansion member 102 with different thermal expansion coefficients (1 / K). Here, thermal expansion coefficient refers to linear expansion coefficient. The thermal expansion coefficient of the high-expansion member 102 is higher than that of the low-expansion member 100. To achieve this, for example, the low-expansion member 100 is made of steel and the high-expansion member 102 is made of aluminum. There are no particular limitations on the specific examples of the low-expansion member 100 and the high-expansion member 102 used to achieve this. For example, the thermal expansion coefficient of the high-expansion member 102 is 2.0 times or more the thermal expansion coefficient of the low-expansion member 100.

[0031] The core material 74 is constructed by combining a low-expansion member 100 and a high-expansion member 102. To achieve this, the core material 74 of this embodiment includes an overlapping section 104A formed by stacking the low-expansion member 100 and the high-expansion member 102. The low-expansion member 100 and the high-expansion member 102 are integrated by bonding their overlapping surfaces together with an adhesive at the overlapping section 104A.

[0032] The core material 74 of this embodiment includes a first overlapping portion 104A, which is formed by stacking a low-expansion member 100 and a high-expansion member 102 radially in the axially extending portion 78. The low-expansion member 100 and the high-expansion member 102 (first overlapping portion 104A) are provided in the axially extending portion 78. In this first overlapping portion 104A, the low-expansion member 100 is provided radially closer to the mating surface 70 than the high-expansion member 102, and the high-expansion member 102 is provided radially opposite to the mating surface 70, with the low-expansion member 100 in between.

[0033] At least one of the low-expansion member 100 and the high-expansion member 102 is integrally provided on the axially extending portion 78 and the radially extending portion 80 of the core material 74. In this embodiment, this condition is satisfied by the high-expansion member 102. The first overlapping portion 104A in this embodiment is provided at a position that overlaps radially with the constituent portion of the radially extending portion 80 of the high-expansion member 102, in addition to the constituent portion of the axially extending portion 78 of the high-expansion member 102. In this embodiment, the side surface 100a of the low-expansion member 100 that constitutes the axially extending portion 78 (first overlapping portion 104A) on the external space 60 side and the side surface 102a of the high-expansion member 102 on the external space 60 side are flush.

[0034] The operation of the seal structure 50 described above will now be explained. Consider the case where the temperature of the low-expansion member 100 and the high-expansion member 102 of the core material 74 rises. The temperature rise here refers to the temperature of both the low-expansion member 100 and the high-expansion member 102 rising from a predetermined normal temperature range to a predetermined high-temperature range. The normal temperature range here refers to, for example, room temperature (20°C to 30°C), and the high-temperature range refers to, for example, a temperature range of 70°C or higher. This temperature rise occurs, for example, in the internal space 56 of the casing 18 due to the heat generated by the meshing of the external gear 22 and internal gear 24 of the gear mechanism 14.

[0035] Refer to Figure 3. In this case, at the first overlapping portion 104A provided on the axially extending portion 78 of the core material 74, the amount of deformation of the low-expansion member 100 in the axial direction X is smaller than the amount of deformation of the high-expansion member 102 in the axial direction X. Therefore, at the first overlapping portion 104A of the core material 74, the deformation of the high-expansion member 102 in the axial direction X is constrained by the low-expansion member 100, and a concave warp deformation is likely to occur on the low-expansion member 100 side. Here, the state after warp deformation at the first overlapping portion 104A of the core material 74, assuming that the casing 18 and inner member 54 are absent, is shown by the dashed line. At this time, the portion of the first overlapping portion 104A of the core material 74 on the external space 60 side is constrained by the radially extending portion 80, so the portion on the internal space 56 side is likely to undergo a large warp deformation.

[0036] As a result, the pressing force F1 applied radially by the axially extended portion 78 of the first sealing member 58A to the mating surface 70 of the casing 18 increases. This increase in pressing force F1 increases the reaction force in the opposite radial direction to the pressing force F1, and the pressing force F2 applied radially by the sealing lip portion 82 of the first sealing member 58A to the lip contact surface 72 of the inner member 54 also increases. In this way, the low-expansion member 100 and the high-expansion member 102 are arranged such that the pressing forces F1 and F2 of the first sealing member 58A against the casing 18 and the inner member 54 increase with increasing temperature. It can also be said that the low-expansion member 100 and the high-expansion member 102 are arranged such that the pressing force F1 of the first sealing member 58A against the mating surface 70 increases with increasing temperature. The low-expansion member 100 and the high-expansion member 102 are arranged such that the pressing force F2 of the seal lip portion 82 against the lip contact surface 72 increases with increasing temperature. To achieve this, the low-expansion member 100 and the high-expansion member 102 of this embodiment can increase the pressing forces F1 and F2 against the casing 18 and inner member 54 as the first overlapping portion 104A tends to warp and deform due to the rising temperature. Compared to the case where the core material 74 is composed of a single member with a uniform thermal expansion coefficient, the low-expansion member 100 and the high-expansion member 102 increase the pressing forces F1 and F2 against the casing 18 and inner member 54.

[0037] The effects of the above sealing structure 50 will now be explained.

[0038] (A) The low-expansion member 100 and the high-expansion member 102 are arranged such that the pressing forces F1 and F2 of the first sealing member 58A against at least one (in this case, both) of the casing 18 and the inner member 54 increase with rising temperature. Therefore, when the internal pressure of the internal space 56 of the casing 18 increases due to rising temperature, leakage of the sealing material that would otherwise pass between at least one of the casing 18 and the inner member 54 and the first sealing member 58A can be suppressed.

[0039] (A) Furthermore, the low-expansion member 100 and the high-expansion member 102 do not increase the pressing force F1 when the temperature is not rising (i.e., when they are in the normal temperature range as described above). Therefore, it becomes easier to position the first sealing member 58A inside the first opening hole 52A, and the assembly of the first sealing member 58A can be improved.

[0040] (A) In particular, if the overlap of the first sealing member 58A with respect to the casing 18 or inner member 54 is increased in order to prevent leakage of the sealing material, it becomes difficult to position the first sealing member 58A inside the first opening hole 52A. In this respect, according to this embodiment, it is not necessary to increase the overlap of the first sealing member 58A in order to prevent leakage of the sealing material. Therefore, it is possible to achieve both ease of assembly of the first sealing member 58A and prevention of leakage of the sealing material.

[0041] (A) In addition, in order to increase the pressing force F1 that pushes the opening hole 52A due to the rise in temperature, a means can be considered in which the thermal expansion coefficient of the first sealing member 58A is greater than that of the member that forms the opening hole 52A (in this case, the casing 18). In this regard, according to this embodiment, by combining members with different thermal expansion coefficients to form the core material 74, the pressing force F1 can be increased due to the rise in temperature. Therefore, in order to achieve the same objective, the restrictions on the thermal expansion coefficients of the member that forms the opening hole 52A and the first sealing member 58A can be eliminated, and the degree of freedom in design can be increased.

[0042] (B) The low-expansion member 100 and the high-expansion member 102 are provided on the axially extending portion 78. Therefore, by increasing the pressing force F1 by the axially extending portion 78 as the temperature rises, the fitting force of the first sealing member 58A against the mating surface 70 can be increased. Consequently, even if the internal pressure of the casing 18 increases due to the rise in temperature, the detachment of the first sealing member 58A can be suppressed.

[0043] (C) At least one of the low-expansion member 100 and the high-expansion member 102 (here, the high-expansion member 102) is integrally provided on the axially extending portion 78 and the radially extending portion 80 of the core material 74. In other words, one of the members constitutes a normal core material 74 having an axially extending portion 78 and a radially extending portion 80. By simply combining the other of the low-expansion member 100 and the high-expansion member 102 (here, the low-expansion member 100) with such a normal core material 74, a core material 74 that increases the pressing force F1 as the temperature rises can be easily obtained.

[0044] (D) When placing the first sealing member 58A in the first opening hole 52A, a jig, fingers, etc. are brought into contact with the side surface of the axially extended portion 78 of the core material 74 on the external space 60 side, and the core material 74 is pushed toward the internal space 56 side in the axial direction X. This operation is performed under the conditions described above, which are within the normal temperature range. Here, the side surfaces 100a and 102a of the low expansion coefficient member 100 and the high expansion coefficient member 102 provided on the axially extended portion 78 of the core material 74 on the external space 60 side are flush. Therefore, compared to the case where there is a step on these side surfaces 100a and 102a, it becomes easier to secure a contact area for the jig, fingers, etc. for pushing the core material 74, and it becomes easier to push the core material 74 toward the internal space 56 side. Consequently, when placing the first sealing member 58A in the first opening hole 52A, the assembly of the first sealing member 58A can be improved.

[0045] (E) The first sealing member 58A is fixed to the inner circumferential surface of the first opening hole 52A and contacts the lip contact surface 72 (outer circumferential surface) of the inner member 54. When there is no temperature rise (i.e., when it is in the normal temperature range described above), the first sealing member 58A does not increase the pressing force F2 that presses against the lip contact surface 72. Therefore, when there is no temperature rise, it is possible to avoid an unnecessary increase in the sliding resistance of the first sealing member 58A against the lip contact surface 72. Consequently, a decrease in the transmission efficiency of the mechanical device 10, which comprises a casing 18 and an inner member 54 that rotate relative to each other, can be avoided. From the viewpoint of obtaining a similar effect, the first sealing member 58A may be fixed to the outer circumferential surface of the inner member 54 and contact the lip contact surface 72 provided on the inner circumferential surface of the first opening hole 52A, as shown in Figure 10 described later.

[0046] (F) Furthermore, the low-expansion member 100 and the high-expansion member 102 are arranged such that the pressing force F2 of the seal lip portion 82 against the lip contact surface 72 increases with increasing temperature. Therefore, by increasing the pressing force F2 that the seal lip portion 82 presses against the lip contact surface 72 with increasing temperature, leakage of the sealing material from between the seal lip portion 82 and the lip contact surface 72 can be suppressed.

[0047] (Second Embodiment) The seal structures 50 of the second to fourth embodiments described below differ from the seal structure 50 of the first embodiment in the configuration of the core material 74.

[0048] Refer to Figure 4. Unlike the first embodiment, the low-expansion member 100 in this embodiment is integrally provided in the axially extending portion 78 and the radially extending portion 80 of the core material 74. Similar to the first embodiment, the high-expansion member 102 and the low-expansion member 100 are stacked radially on top of each other in the axially extending portion 78 to form a first overlapping portion 104A. Similar to the first embodiment, in this first overlapping portion 104A, the low-expansion member 100 is provided radially closer to the mating surface 70 than the high-expansion member 102, and the high-expansion member 102 is provided radially opposite to the mating surface 70, with the low-expansion member 100 in between. Unlike the first embodiment, the first overlapping portion 104A in this embodiment is provided at a position that radially overlaps only with the constituent portion of the axially extending portion 78 of the low-expansion member 100, and is not provided at a position that radially overlaps with the constituent portion of the radially extending portion 80 of the low-expansion member 100.

[0049] The high-expansion-rate member 102 is positioned radially by contacting the lip contact surface 72 side (in this case, the inner circumferential surface) of the other member in the axially extending portion 78. Furthermore, the high-expansion-rate member 102 is positioned axially by contacting the surface of the other member on the axial side opposite to the external space (the side in the axial direction opposite to the external space) in the radially extending portion 80. Thus, the assembly of the core material 74 can be improved. Here, "other member" refers to a member other than the high-expansion-rate member 102 that constitutes the core material 74. In this embodiment, this "other member" refers to the low-expansion-rate member 100, but it may be a member other than the low-expansion-rate member 100 that constitutes the core material 74.

[0050] In this embodiment as well, similar to the first embodiment, the low-expansion member 100 and the high-expansion member 102 are arranged such that the pressing forces F1 and F2 of the first sealing member 58A against the casing 18 and the inner member 54 increase as the temperature rises.

[0051] Furthermore, the axially extending portion 78 and the radially extending portion 80 of the core material 74 can be made flush with the external space 60 by constructing them with the same material (low expansion coefficient member 100). This makes it easier to secure contact area for jigs, fingers, etc., for pushing the core material 74 from the external space 60 side, and makes it easier to push the core material 74 toward the internal space 56 side.

[0052] In addition, the seal structure 50 of this embodiment provides the effects described above (A), (B), (C), (E), and (F).

[0053] (Third Embodiment) Refer to Figure 5. In this embodiment, the high expansion coefficient member 102 is integrally provided in the axially extending portion 78 and the radially extending portion 80 of the core material 74. The core material 74 includes a second overlapping portion 104B formed by stacking the high expansion coefficient member 102 and the low expansion coefficient member 100 in the axial direction X in the radially extending portion 80. The second overlapping portion 104B is provided in the radially extending portion 80. Similar to the first overlapping portion 104A, the second overlapping portion 104B is integrated by bonding the overlapping surfaces of the low expansion coefficient member 100 and the high expansion coefficient member 102 with an adhesive in the second overlapping portion 104B.

[0054] In this radially extending portion 80 (second overlapping portion 104B), the low-expansion member 100 is provided on the external space 60 side in the axial direction X than the high-expansion member 102, and the high-expansion member 102 is provided on the internal space 56 side in the axial direction X than the high-expansion member 102. In this embodiment, the second overlapping portion 104B is provided at a position that overlaps in the axial direction X with the components of the radially extending portion 80 of the high-expansion member 102, as well as the components of the axially extending portion 78 of the low-expansion member 100.

[0055] The operation of the seal structure 50 described above will now be explained. Refer to Figure 6. Similar to the first embodiment, consider the case where the temperature of the low-expansion member 100 and the high-expansion member 102 of the core material 74 rises. In this case, at the second overlapping portion 104B provided on the radially extending portion 80 of the core material 74, the amount of radial deformation of the low-expansion member 100 is smaller than the amount of radial deformation of the high-expansion member 102. Therefore, at the second overlapping portion 104B of the core material 74, the radial deformation of the high-expansion member 102 is constrained by the low-expansion member 100, and a concave warp deformation is about to occur on the low-expansion member 100 side. Here, assuming that the casing 18 and inner member 54 are absent, the state after warp deformation at the second overlapping portion 104B of the core material 74 is shown by a dashed line. At this time, the portion of the core material 74 on the mating surface 70 side of the second overlapping portion 104B is constrained by the axially extending portion 78, causing the portion on the lip contact surface 72 side to undergo significant warping deformation. Along with this warping deformation, the seal lip portion 82 of the first seal member 58A attempts to move in direction Da so as to approach the lip contact surface 72 side.

[0056] As a result, the pressing force F2 applied radially by the sealing lip portion 82 of the first sealing member 58A to the lip contact surface 72 of the inner member 54 increases. This increase in pressing force F2 increases the reaction force in the opposite direction radially to the pressing force F2, thereby increasing the pressing force F1 applied radially by the axially extended portion 78 of the first sealing member 58A to the mating surface 70 of the casing 18. Thus, the low-expansion member 100 and the high-expansion member 102 are arranged such that the pressing forces F1 and F2 of the first sealing member 58A against the casing 18 and the inner member 54 increase with increasing temperature. It can also be said that the low-expansion member 100 and the high-expansion member 102 are arranged such that the pressing force F1 of the first sealing member 58A against the mating surface 70 increases with increasing temperature. The low-expansion member 100 and the high-expansion member 102 are arranged such that the pressing force F2 of the seal lip portion 82 against the lip contact surface 72 increases with increasing temperature. To achieve this, the low-expansion member 100 and the high-expansion member 102 of this embodiment can increase the pressing forces F1 and F2 against the casing 18 and the inner member 54 as the second overlap portion 104B attempts to warp and deform due to the rising temperature. Similar to the first embodiment, the low-expansion member 100 and the high-expansion member 102 increase the pressing forces F1 and F2 against the casing 18 and the inner member 54 compared to the case where the core material 74 is composed of a single member with a uniform thermal expansion coefficient.

[0057] According to the seal structure 50 described above, the effects of (A), (C), (E), and (F) mentioned above can be obtained.

[0058] (G) Furthermore, the axially extending portion 78 and the radially extending portion 80 of the core material 74 can be made flush with the external space 60 by constructing them with the same material (low expansion coefficient member 100). This makes it easier to secure contact area for jigs, fingers, etc., for pushing the core material 74 from the external space 60 side, and makes it easier to push the core material 74 toward the internal space 56 side.

[0059] (Fourth Embodiment) Refer to Figure 7. In this embodiment, the low expansion ratio member 100 is integrally provided in the axially extending portion 78 and the radially extending portion 80 of the core material 74. Similar to the third embodiment, the high expansion ratio member 102 and the low expansion ratio member 100 constitute a second overlapping portion 104B that stacks in the axial direction X in the radially extending portion 80. Similar to the third embodiment, in this radially extending portion 80 (second overlapping portion 104B), the low expansion ratio member 100 is provided on the external space 60 side of the high expansion ratio member 102 in the axial direction X, and the high expansion ratio member 102 is provided on the internal space 56 side of the low expansion ratio member 100 in the axial direction X. In this embodiment, the second overlapping portion 104B is provided in a position that overlaps in the axial direction X only with the constituent portion of the radially extending portion 80 of the low expansion ratio member 100, and is not provided in a position that overlaps in the axial direction X with the constituent portion of the axially extending portion 78 of the low expansion ratio member 100.

[0060] Similar to the second embodiment, the high-expansion member 102 is positioned radially by contacting the lip contact surface 72 side (in this case, the inner circumferential surface) of another member (in this case, the low-expansion member 100) at the axially extending portion 78. Furthermore, the high-expansion member 102 is positioned axially by contacting the surface of the other member (in this case, the low-expansion member 100) on the side opposite to the external space at the radially extending portion 80. Thus, the assembly of the core material 74 can be improved.

[0061] In this embodiment as well, similar to the third embodiment, the low-expansion member 100 and the high-expansion member 102 are arranged such that the pressing forces F1 and F2 of the first sealing member 58A against the casing 18 and the inner member 54 increase as the temperature rises.

[0062] In addition, the seal structure 50 of this embodiment provides the effects described above (A), (C), (E), (F), and (G).

[0063] (Fifth Embodiment) Refer to Figure 8. Next, an example of applying the main features of the seal structure 50 of this disclosure (low expansion ratio member 100 and high expansion ratio member 102) to the second seal member 58B (seal cap) will be described. Here, an example of application to the second seal member 58B located in the central through hole 38 (second opening hole 52B) in Figure 1 will be described, but it may also be applied to the second seal member 58B located in the offset through hole 40 in Figure 1. The inner circumferential surface of the second opening hole 52B in which the second seal member 58B is located is provided with a fitting surface 70 that fixes the second seal member 58B in a fitted state.

[0064] The second sealing member 58B, like the first embodiment, comprises a core material 74 and an elastic material 76. The core material 74 comprises a cylindrical axially extending portion 78 and a radially extending portion 80 extending radially from the axially extending portion 78. In this embodiment, the radially extending portion 80 is plate-shaped. The elastic material 76, like the first embodiment, comprises a first covering portion 86 that covers the axially extending portion 78 and a second covering portion 88 that covers the radially extending portion 80.

[0065] The core material 74 of this embodiment, like the first embodiment, includes a first overlapping portion 104A formed by stacking a low-expansion member 100 and a high-expansion member 102 radially in the axially extending portion 78. The first overlapping portion 104A of this embodiment is provided in the axially extending portion 78, similar to the first embodiment.

[0066] In this case as well, similar to the first sealing member 58A, the low-expansion member 100 and the high-expansion member 102 increase the pressing force F1 against the inner member 54 as the temperature rises. To achieve this, the low-expansion member 100 and the high-expansion member 102 of this embodiment can increase the pressing force F1 against the inner member 54 as the first overlapping portion 104A of the core material 74 attempts to warp and deform as the temperature rises. Therefore, similar to the matter described in (A) of the first embodiment, leakage of the sealing material attempting to pass between the inner member 54 and the second sealing member 58B can be suppressed.

[0067] In addition, as described in (B) of the first embodiment, the fitting force of the second seal member 58B against the mating surface 70 can be increased by increasing the pressing force F1 by the axially extended portion 78 as the temperature rises. In addition, as described in (D), the sides 100a and 102a on the external space 60 side of the low expansion coefficient member 100 and high expansion coefficient member 102 provided on the axially extended portion 78 of the core material 74 are flush. Therefore, the axially extended portion 78 of the core material 74 is easier to push toward the internal space 56, and the assembly of the second seal member 58B can be improved when arranging the second seal member 58B in the second opening hole 52B.

[0068] Refer to Figure 9. When the core material 74, which includes a low-expansion member 100 and a high-expansion member 102, is applied to the second seal member 58B, the configuration described in Figure 4 may also be applied. That is, the low-expansion member 100 may be integrally provided in the axially extending portion 78 and the radially extending portion 80, and the high-expansion member 102 may be provided in the axially extending portion 78 on the radially opposite side from the mating surface 70 to the low-expansion member 100.

[0069] (Sixth Embodiment) Refer to Figure 10. In the first to fourth embodiments, an example was described in which the axially extended portion 78 of the first seal member 58A is fixed to the inner circumferential surface (fitting surface 70) of the first opening hole 52A, and its seal lip portion 82 contacts the outer circumferential surface (lip contact surface 72) of the inner member 54. Alternatively, the axially extended portion 78 of the first seal member 58A may be fixed to the outer circumferential surface (fitting surface 70) of the inner member 54, and its seal lip portion 82 contacts the inner circumferential surface (lip contact surface 72) of the first opening hole 52A. In other words, the first seal member 58A only needs to be fixed to either the inner circumferential surface of the first opening hole 52A or the outer circumferential surface of the inner member 54 and in contact with the other. From another point of view, it can also be said that the lip contact surface 72 may be provided on the inner circumferential surface of the first opening hole 52A, and the fitting surface 70 may be provided on the outer circumferential surface of the inner member 54. In other words, a fitting surface 70 may be provided on one of the inner circumferential surface of the first opening hole 52A and the outer circumferential surface of the inner member 54, and a lip contact surface 72 may be provided on the other.

[0070] Next, we will describe the modified forms of each component described so far. Hereafter, when referring to components (such as sealing members) with "A, B, C" appended to the end of their symbols, these will be omitted.

[0071] The specific examples of the mechanical device 10 in which the sealing member 58 of this disclosure is used are not particularly limited. The mechanical device 10 (seal structure 50) does not necessarily have to include an inner member 54. For example, this assumes a case where the oil supply hole provided in the casing 18 becomes an opening 52A, and the second sealing member 58B (seal cap) is placed in that opening 52A.

[0072] When the mechanical device 10 is a rotating device, it may be a gear system, or for example, a traction drive, a motor, etc. Also, when the mechanical device 10 is a rotating device, the specific example of the inner member 54 is not particularly limited and may be a rotating shaft, etc.

[0073] When the mechanical device 10 is a gear device, the specific example of the gear device is not particularly limited. The gear device may be any of the following: an eccentric oscillating gear device, a flexible meshing gear device, a simple planetary gear device, a right-angle gear device, a parallel-axis gear device, etc. The type of eccentric oscillating gear device is not particularly limited. This type may be a distribution type in which the crankshaft 28 is provided at an offset position from the center C24 of the internal gear 24, as in the embodiment, or a center crank type in which the crankshaft 28 is provided on the center C24 of the internal gear 24. The type of flexible meshing gear device is not particularly limited. This type may be a cylindrical type using a pair of internal gears, or a top hat type or cup type using a single internal gear.

[0074] In relation to the effect of (A), the low-expansion member 100 and the high-expansion member 102 should be arranged such that the pressing forces F1 and F2 of the sealing members against at least one of the casing 18 and the inner member 54 increase as the temperature rises. To achieve this, the low-expansion member 100 and the high-expansion member 102 do not have to overlap, and may be arranged with a gap between them. Also, to achieve this, the low-expansion member 100 and the high-expansion member 102 may be arranged by scattering the other member inside the other member. Furthermore, for example, if the machine device 10 does not have an inner member 54 and the second sealing member 58B is placed in the opening hole 52A of the casing 18, they may be arranged such that the pressing force F1 of the sealing member 58A against only the casing 18 increases.

[0075] In the embodiment described, the core material 74 of the first sealing member 58A is provided with only one of the first overlapping portion 104A and the second overlapping portion 104B. However, the core material 74 of the first sealing member 58A may also be provided with both the first overlapping portion 104A and the second overlapping portion 104B.

[0076] In relation to the effect of (C), it is sufficient that at least one of the low-expansion member 100 and the high-expansion member 102 is integrally provided with the axially extending portion 78 and the radially extending portion 80 of the core material 74. For example, both the low-expansion member 100 and the high-expansion member 102 may satisfy this condition.

[0077] In the example shown in Figure 2, the sides of the low-expansion member 100 and the high-expansion member 102 facing the external space 60 do not need to be flush. Furthermore, in order to make the sides 100a and 102a of the low-expansion member 100 and the high-expansion member 102, which are provided on the axially extending portion 78 of the core material 74, flush, the axially extending portion 78 and the radially extending portion 80 of the core material 74 do not need to be integrated.

[0078] As shown in Figure 4, when the core material 74 is provided with a first overlapping portion 104A, the high-expansion-rate member 102 does not need to be positioned in the axial direction by contacting another member in the radially extending portion 80. As shown in Figure 7, when the core material 74 is provided with a second overlapping portion 104B, the high-expansion-rate member 102 does not need to be positioned in the radial direction by contacting another member in the axially extending portion 78.

[0079] The embodiments and variations described above are illustrative. The abstract technical ideas derived from them should not be interpreted restrictively to the content of the embodiments and variations. Many design changes, such as changes, additions, and deletions of components, are possible in the embodiments and variations. In the embodiments described above, the content that allows for such design changes is emphasized with the notation "embodiment." However, design changes are also permitted in content without such notation. The hatching applied to the cross-sections in the drawings does not limit the material to which the hatching is applied. The structures / numerical values ​​mentioned in the embodiments and variations naturally include those that can be considered identical when considering manufacturing tolerances, etc. [Explanation of Symbols]

[0080] 18...Casing, 50...Seal structure, 52A, 52B...Opening hole, 54...Inner member, 56...Internal space, 58A, 58B...Seal member, 60...External space, 70...Mating surface, 72...Lip contact surface, 74...Core material, 76...Elastic material, 78...Axial extension, 80...Radial extension, 82...Seal lip portion, 100...Low expansion coefficient member, 102...High expansion coefficient member, 104A...First overlapping portion, 104B...Second overlapping portion.

Claims

1. A seal structure comprising a casing, an inner member disposed within an opening in the casing and rotating relative to the casing, and a sealing member for sealing the internal space of the casing, The sealing member is positioned within the opening hole and fixed to either the inner circumferential surface of the opening hole or the outer circumferential surface of the inner member, and in contact with the lip contact surface provided on the other side. The sealing member comprises a core material and an elastic material integrated with the core material, The core material is constructed by combining a low-expansion member and a high-expansion member with different thermal expansion coefficients. The low-expansion member and the high-expansion member are arranged such that the pressing force of the sealing member against at least one of the casing and the inner member increases as the temperature rises. The core material comprises a radially extending portion extending in the radial direction and a cylindrical axially extending portion extending from the radially extending portion in one axial direction, The elastic material includes a seal lip portion that extends from the end of the radially extending portion on the lip contact surface side toward the lip contact surface and contacts the lip contact surface. The seal lip portion is a seal structure in which the low-expansion member and the high-expansion member are not provided on one side in the axial direction from the end of the radially extending portion.

2. The seal structure according to claim 1, wherein the low-expansion ratio member and the high-expansion ratio member are provided in the axially extending portion.

3. The sealing member fits into a fitting surface provided on either the inner circumferential surface of the opening or the outer circumferential surface of the inner member. The axially extending portion includes a first overlapping portion formed by stacking the low-expansion-rate member and the high-expansion-rate member in the radial direction, The seal structure according to claim 2, wherein the low-expansion member is provided on the mating surface side of the first overlapping portion than the high-expansion member.

4. The seal structure according to claim 2 or 3, wherein the side surfaces of the high-expansion-rate member and the low-expansion-rate member provided in the axially extending portion are flush with the external space.

5. The seal structure according to claim 3, wherein the high expansion coefficient member is positioned axially by contacting the surface of another member on the side opposite to the external space in the radially extending portion.

6. The seal structure according to any one of claims 2 to 5, wherein at least one of the low-expansion-rate member and the high-expansion-rate member is integrally provided with the axially extending portion and the radially extending portion.

7. The seal structure according to any one of claims 1 to 6, wherein the low-expansion member and the high-expansion member are arranged such that the pressing force of the seal lip portion against the lip contact surface increases with increasing temperature.

8. The radially extending portion includes a second overlapping portion formed by stacking the low-expansion-rate member and the high-expansion-rate member in the axial direction, The seal structure according to claim 7, wherein the low-expansion-rate member is provided in the second overlapping portion on the external space side than the high-expansion-rate member.

9. The seal structure according to claim 8, wherein the high expansion coefficient member is positioned radially by contacting the surface of another member on the lip contact surface side in the axially extending portion.

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