Gear system

Abstract

One of the objectives of this invention is to provide a gear device that can secure the volume of the sealing space. [Solution] The gear device 10 of the embodiment includes a shaft 1, a first member 2, a seal member S1 interposed between the shaft 1 and the first member 2 to seal the space between the internal space A and the external space E, a gear mechanism enclosed in the second space A2 of the internal space A, and a bearing 4 positioned on the shaft 1 in the axial direction between the gear mechanism and the seal member S1. The space A11 where the seal member S1 is positioned and the space A12 of the bearing 4 are in communication to form the first space A1, the space A1 and the space A2 are shielded from each other, and different lubricants G1 and G2 are used in the first space A1 and the second space A2.

Description

Technical Field

[0001] The present invention relates to a gear device.

Background Art

[0002] There is known a transmission that decelerates and outputs an input rotation. For example, Patent Document 1 describes a transmission having a transmission mechanism inside a casing. This transmission includes a casing, a shaft, a bearing that supports this shaft, an oil seal means disposed between the shaft and the casing, and a transmission mechanism. The shaft protrudes from the casing, and the transmission mechanism is housed in the casing in a sealed state by the oil seal means. With this configuration, the lubricant of the transmission mechanism is prevented from mixing into the lubricant that lubricates the oil seal means.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The inventor obtained the following recognition about the transmission described in Patent Document 1. In this transmission, since it is necessary to provide shielding means to seal the transmission mechanism inside the casing, a seal bearing having a seal function is adopted for the bearing. For this reason, the seal space where the oil seal means is disposed is blocked on the oil seal means side of the bearing, so that the volume of the seal space becomes small. When the volume of the seal space becomes small, for example, the pressure inside the seal space may increase due to the movement of the shaft or a temperature rise, and problems such as leakage of the lubricant and extrusion of the oil seal means to the outside may occur.

[0005] One might consider increasing the distance between the oil seal and the bearing to increase the volume of the seal space, but this would result in the transmission becoming larger in the axial direction.

[0006] From these points, it can be said that Patent Document 1 does not provide sufficient disclosure from the standpoint of ensuring the volume of the sealing space.

[0007] This invention has been made in view of these problems, and one of its objectives is to provide a gear device that can secure a larger volume of seal space. [Means for solving the problem]

[0008] To solve the above problems, a gear device according to one aspect of the present invention includes a shaft, a first member, a sealing member interposed between the shaft and the first member to seal the space between an internal space and an external space, a gear mechanism enclosed in a second space within the internal space, and a bearing positioned on the shaft axially between the gear mechanism and the sealing member. The space where the sealing member is positioned and the space of the bearing communicate to form a first space, the space between the first space and the second space is shielded, and different lubricants are used in the first space and the second space.

[0009] Furthermore, any combination of the above components, or in which the components or expressions of the present invention are mutually substituted among methods, systems, etc., are also valid embodiments of the present invention. [Effects of the Invention]

[0010] According to the present invention, a gear device is available that can secure the volume of the sealing space. [Brief explanation of the drawing]

[0011] [Figure 1] This is a cross-sectional view showing a gear device according to an embodiment. [Figure 2] This is a cross-sectional view showing the area around the seal member and bearing of the gear mechanism shown in Figure 1. [Figure 3] This is a cross-sectional view showing an enlarged view of the lubricant shielding structure in Figure 2. [Modes for carrying out the invention]

[0012] The present invention will be described below with reference to the drawings, based on preferred embodiments. In embodiments and modifications, the same or equivalent components and members will be denoted by the same reference numerals, and redundant explanations will be omitted as appropriate. In addition, the dimensions of the members in each drawing will be enlarged or reduced as appropriate for ease of understanding. Furthermore, some members that are not important for explaining the embodiments will be omitted from the drawings.

[0013] Furthermore, while terms including ordinal numbers such as "first" and "second" are used to describe various components, these terms are used solely to distinguish one component from others, and do not limit the components themselves.

[0014] [Embodiment] A gear assembly 10 according to an embodiment will be described with reference to the drawings. First, the overall configuration of the gear assembly 10 will be described with reference to Figure 1, and the lubrication shielding structure, which is a characteristic configuration of this embodiment, will be described later. The gear assembly 10 mainly comprises an input shaft 20, a gear mechanism 9, carriers 35, 36, a casing 6, main bearings 26, 27, input shaft bearings 37, 38, sealing members S1, S2, and outer sealing members S3, S4. The gear mechanism 9 has external gears 14, 15 and internal gears 16 that mesh with each other. The input shaft bearings 37, 38 include a first input shaft bearing 37 located on the non-input side of the external gears 14, 15, and a second input shaft bearing 38 located on the input side of the external gears 14, 15. The input shaft bearings 37, 38 in this example are deep groove ball bearings, but are not limited to these.

[0015] The input shaft 20 and input shaft bearings 37 and 38 illustrate the shaft 1 and bearing 4 of the claims. The carriers 35 and 36 also illustrate the first member 2 of the claims.

[0016] The gear unit 10 comprises external gears 14, 15 and internal gears 16 that constitute the gear mechanism 9, and functions as an eccentric oscillating type reducer that reduces the rotation input to the input shaft 20 from a drive source (not shown), such as a servo motor, and outputs it from the output member 40. The casing 6 houses the gear mechanism 9 and carriers 35, 36.

[0017] The input shaft 20 comprises a shaft body 21 and two eccentric portions 24 and 25 that are eccentric with respect to the rotation center of the shaft body 21. The number of eccentric portions may be one or three or more. The external gears 14 and 15 are provided corresponding to the two eccentric portions 24 via eccentric rollers 47 and each has three internal pin holes 41 and 42 that are equally spaced in the circumferential direction. An internal pin 48 is inserted through each internal pin hole 41 and 42. The external gears 14 and 15 are configured to swing as the external teeth formed on the outer circumference of the external gears 14 and 15 move in contact with the internal gear 16.

[0018] The internal gear 16 has an internal gear body 18 integrated with the inner circumference of the casing 6, and an external pin 17 positioned in a pin groove 19 formed in the internal gear body 18. The external pin 17 is rotatably supported in the pin groove 19 which extends in the axial direction. The external pin 17 is a cylindrical pin member that extends in the axial direction, constitutes the internal teeth of the internal gear 16, and meshes with the external teeth of the external gears 14 and 15. The number of external pins 17 is slightly greater than the number of external teeth of the external gears 14 and 15 (only one in this example).

[0019] The carriers 35 and 36 include a first carrier 35 positioned on the non-input side of the external gears 14 and 15, and a second carrier 36 positioned on the input side of the external gears 14 and 15. The carriers 35 and 36 are synchronized with the rotational component of the external gears 14 when the external gears 14 oscillate, by an internal pin 48 that passes through the external gears 14 and 15.

[0020] The main bearings 26 and 27 include a first main bearing 26 disposed on the side of the outer gear wheels 14 and 15 opposite to the input side, and a second main bearing 27 disposed on the side of the outer gear wheels 14 and 15 on the input side. The main bearings 26 and 27 support the casing 6. The main bearings 26 and 27 in this example are angular ball bearings, but are not limited thereto. The carriers 35 and 36 are rotatably supported by the casing 6 via the main bearings 26 and 27. The outer seal members S3 and S4 are interposed between the carriers 35 and 36 and the casing 6, and function as oil seals that seal the space between the main bearings 26 and 27 and the external space of the gear device 10.

[0021] Referring also to FIGS. 2 and 3, a shielding structure, which is a characteristic configuration of the gear device 10 of the embodiment, will be described. FIG. 2 is a cross-sectional view showing the periphery of the seal members S1 and S2 and the bearings 4 of the gear device 10. FIG. 3 is an enlarged cross-sectional view showing the shielding structure 8 of the lubricants G1 and G2. As shown in FIG. 2, the shielding structures 7 and 8 include a first shielding structure 7 disposed on the side of the gear mechanism portion 9 opposite to the input side, and a second shielding structure 8 disposed on the input side of the gear mechanism portion 9. Since the shielding structures 7 and 8 have the same configuration, hereinafter, mainly the shielding structure 8 will be described, but this description is also applicable to the shielding structure 7.

[0022] As shown in FIG. 2, seal members S1 and S2 are provided to seal the space between the internal space A of the gear device 10 and the external space E of the gear device 10. The internal space A of the gear device 10 is separated into a first space A1 where the lubricant G1 is used and a second space A2 where a lubricant G2 different from the lubricant G1 is used, and are shielded from each other by the shielding structure 7. The lubricants G1 and G2 may be applied to the members in the spaces A1 and A2, may be injected into the spaces, or may be filled.

[0023] The first space A1 is a space formed by the communication between the space A11 where the seal member S1 is located and the space A12 of the bearing 4. The space A11 where the seal member S1 is located includes the internal space on the non-input side of the seal member S1 and the space between the non-input side of the seal member S1 and the input side of the bearing 4. The space A12 of the bearing 4 is the space on the outer side of the shield in the annular space between the outer ring and the inner ring. The second space A2 is the space on the inner circumference side of the casing 6 in which the gear mechanism 9 is enclosed.

[0024] The sealing member S1 is interposed between the shaft 1 and the first member 2, sealing the space between the internal space A and the external space E. In the example shown in Figure 3, the sealing member S1 is an oil seal interposed between the outer circumferential surface of the input shaft 20 and the inner circumferential surface of the second carrier 36, and the sealing member S2 is an oil seal interposed between the outer circumferential surface of the input shaft 20 and the inner circumferential surface of the first carrier 35.

[0025] As the lubricant G2 used in the second space A2 in which the gear mechanism 9 is enclosed, a lubricant that can reduce seizure of the sliding parts is preferred, since excessive load is applied to the sliding parts such as gears due to torque transmission. To reduce seizure of the sliding parts, it is desirable to add extreme pressure additives to the lubricant G2. As these extreme pressure additives, one or more of the components Mo (molybdenum), S (sulfur), Cl (chlorine), and P (phosphorus) can be used in combination. In addition, in order to maintain various properties, it contains one of the components Li (lithium), Na (sodium), Ba (barium), Ni (nickel), and pb (lead). In addition, it is not necessary to contain some or all of these components.

[0026] On the other hand, when a specific component of lubricant G1 reaches the sealing members S1 and S2, the temperature rise caused by the sliding of the sealing members S1 and S2 against the shaft 1 can lead to a chemical reaction in the specific component, generating precipitates that can become lodged in the lips of the sealing members S1 and S2, impairing their function. Therefore, in this embodiment, lubricant G2 differs from lubricant G1 in that it does not contain a specific component that is prone to generating precipitates, and is a lubricant that is less likely to generate precipitates. One example of this specific component is Mo (molybdenum). On the other hand, in order to maintain various properties, it contains one of the following components: Li (lithium), Na (sodium), Ba (barium), Ni (nickel), and pb (lead). It should be noted that it is not necessary to contain some or all of these components.

[0027] In the example shown in Figure 2, the bearing 4 is positioned on the shaft 1 in the axial direction between the gear mechanism 9 and the seal member S1. The second input shaft bearing 38 is positioned on the input shaft 20 in the axial direction between the gear mechanism 9 and the seal member S1. The input shaft 20, the second input shaft bearing 38, the seal member S1, and the second carrier 36 constitute the second shielding structure 8, which is positioned on the input side of the gear mechanism 9.

[0028] The first input shaft bearing 37 is positioned on the input shaft 20 in the axial direction between the gear mechanism 9 and the seal member S2. The input shaft 20, the first input shaft bearing 37, the seal member S2, and the first carrier 35 constitute the first shielding structure 7, which is positioned on the side of the gear mechanism 9 opposite to the input. In this way, the gear device 10 is equipped with two shielding structures 7 and 8 flanking the gear mechanism 9. In this case, compared to the case where a shielding structure is provided on only one side, the possibility of lubricant G2 leaking to the seal members S1 and S2 and its precipitates getting caught in the lip portions of the seal members S1 and S2 can be reduced.

[0029] To construct a shielding structure, it is conceivable to provide a shielding means in addition to the bearing 4 and sealing members S1 and S2, but in this case, the axial size would increase by the amount of the shielding means. Therefore, in this embodiment, as shown in Figure 3, the shielding means that shields the space between the first space A1 and the second space A2 is the shield 383 of the bearing 4. Since the shielding means is housed within the bearing 4, it is advantageous for miniaturization in the axial direction and the assembly man-hours can also be reduced.

[0030] In the example shown in Figure 3, the bearing 4 includes an outer ring 381, an inner ring 382, ​​a shield 383, rolling elements 384, and a retainer 385. The bearing 4 is a so-called single-shielded type, where the end closer to the sealing member S1 is open between the outer ring 381 and the inner ring 382, ​​and the end further away from the sealing member S1 is closed by the shield 383. Because the end closer to the sealing member S1 is open, the space A12 of the bearing 4 communicates with and integrates with the space A11 where the sealing member S1 is located, forming a first space A1. The volume of the first space A1 can be increased compared to when using a double-shielded type.

[0031] In bearing 4, the seal is a contact-type sealed bearing in which the seal contacts the inner ring. The outer circumference of the shield 383 is housed in the circumferential groove of the outer ring 381, and the inner circumference of the shield 383 is housed in the circumferential groove of the inner ring 382. For example, the shield 383 is formed from a steel plate whose surface is covered with a resin such as rubber. Because bearing 4 is a contact-type sealed bearing, the shielding performance of the shield 383 is higher than that of a non-contact type, and leakage of the lubricant G2 into the first space A1 can be reduced. However, a non-contact type sealed bearing in which the shield 383 does not contact the inner ring is also acceptable.

[0032] In this embodiment, the sealing member S1 is positioned on shaft 1, which is an input shaft 20 that is an eccentric shaft having eccentric portions 24 and 25 that cause the external gears 14 and 15 to oscillate. The eccentric shaft oscillates and moves in response to the change in the magnitude of the force received by the eccentric portion from the external gears 14 and 15 due to the rotational phase of the eccentric portion. As a result, pressure changes in the first space A1 due to the movement of shaft 1, which is an eccentric shaft, are more likely to occur, and the effect of the shielding structure becomes more pronounced.

[0033] Alternatively, the sealing member S1 may be positioned on a vibrator shaft having a vibrator that causes a flexible external gear to flex and oscillate. Similar to the eccentric shaft described above, the magnitude of the force received by the external gear on the vibrator shaft changes significantly depending on the rotational phase. As a result, even when shaft 1 is a vibrator shaft, the effect of the shielding structure becomes more pronounced, similar to the case of the eccentric shaft described above.

[0034] The operation of the reduction gear described above will now be explained. When the input shaft 20 rotates due to the rotation transmitted from the drive source, the external gears 14 and 15 oscillate due to the eccentric portion 24 of the input shaft 20. As the external gears 14 and 15 oscillate, the meshing position of the external gears 14 and 15 and the internal gear 16 changes sequentially in the circumferential direction. As a result, with each rotation of the input shaft 20, either the external gears 14 and 15 or the internal gear 16 (in this case, the external gears 14 and 15) rotates by the difference in the number of teeth between them. This rotational component is transmitted to the first carrier 35, which is the output member 40, via the internal pin 48, and output from the output member 40 to the driven member (not shown) as output rotation.

[0035] The features of the gear device 10 configured as described above will now be explained. The gear device 10 includes a shaft 1, a first member 2, a seal member S1 interposed between the shaft 1 and the first member 2 to seal the space between the internal space A and the external space E, a gear mechanism 9 enclosed in the second space A2 of the internal space A, and a bearing 4 positioned on the shaft 1 in the axial direction between the gear mechanism 9 and the seal member S1. The space A11 where the seal member S1 is positioned and the space A12 of the bearing 4 are in communication to form the first space A1, the space A1 and the space A2 are shielded from each other, and different lubricants G1 and G2 are used in the first space A1 and the second space A2.

[0036] With this configuration, the space between the first space A1 and the second space A2 is shielded, which reduces the leakage of the lubricant G1 from the first space A1 into the second space A2. Furthermore, since the space A12 of the bearing 4 and the seal space A11 where the seal member S1 is located are connected and shared, the volume of the first space A1 increases. As a result, the pressure rise in the first space A1 caused by the movement of the shaft 1 or the temperature rise is mitigated, making it less likely for problems such as lubricant leakage or the oil seal means to come loose to occur. In addition, problems caused by the pressure drop in the first space A1 due to the movement of the shaft 1 also become less likely to occur.

[0037] As an example, the shielding means that shields the space between the first space A1 and the second space A2 is the shield 383 of the bearing 4. In this case, since the shielding means is housed within the bearing 4, it is advantageous for miniaturization in the axial direction.

[0038] For example, the lubricant G1 used in the first space A1 does not contain Mo (molybdenum). In this case, the generation of precipitates from the lubricant G1 can be reduced.

[0039] As an example, the sealing member S1 is positioned on a shaft 1 which is an eccentric shaft having eccentric portions 24 and 25 that cause the external gears 14 and 15 to oscillate. Alternatively, the sealing member S1 may be positioned on a vibrator shaft having a vibrator that causes a flexible external gear to flex and oscillate. In these cases, the effect of the shielding structure becomes more pronounced because the eccentric shaft or vibrator shaft is easily movable.

[0040] The above is a description of the embodiment.

[0041] The present invention has been described above based on the embodiments. These embodiments are illustrative, and it will be understood by those skilled in the art that various modifications and changes are possible within the scope of the claims of the present invention, and that such modifications and changes are also within the scope of the claims of the present invention. Accordingly, the descriptions and drawings herein should be treated as illustrative rather than limiting.

[0042] (modified version) The following describes modified examples. In the drawings and descriptions of the modified examples, components and parts that are the same as or equivalent to those in the embodiments are denoted by the same reference numerals. Descriptions that overlap with those in the embodiments will be omitted as appropriate, and the descriptions will focus on the configurations that differ from those in the embodiments.

[0043] In the above description, the gear device 10 was shown as an example in which the gear mechanism 9 is a so-called center-crank type eccentric oscillating reducer in which the crankshaft is positioned at the axis of the internal gear, but the present invention is not limited to this. Various gear mechanisms based on known principles can be employed for the gear mechanism. For example, the gear mechanism may be a so-called distribution type reducer in which multiple crankshafts are positioned at offset positions from the axis of the internal gear, or it may simply be a gear mechanism with only one gear.

[0044] The above description shows an example in which the gear unit 10 has two external gears 14, but the present invention is not limited to this. The eccentric oscillating type reducer may have one or three or more external gears.

[0045] Each of these modifications produces the same functions and effects as the embodiments.

[0046] Any combination of the embodiments and modifications described above is also useful as an embodiment of the present invention. The new embodiments resulting from these combinations possess the combined effects of both the respective embodiments and modifications. [Explanation of symbols]

[0047] 1 Shaft, A1 First space, G1 Lubricant, 2 First member, A2 Second space, G2 Lubricant, S1, S2 Seal members, 4 Bearing, 7, 8 Shielding structure, 9 Gear mechanism, 10 Gear device, A11, A12 Space, 14 External gear, 24 Eccentric part, 383 Shield.

Claims

1. The axis and First member and A sealing member interposed between the shaft and the first member, sealing the space between the internal space and the external space, The gear mechanism is enclosed in the second space of the aforementioned internal space, A bearing is positioned on the shaft between the gear mechanism and the seal member in the axial direction, It has, The space in which the sealing member is arranged and the space of the bearing are in communication to form a first space. The space between the first space and the second space is shielded. The lubricants used in the first space and the second space are different. Gear mechanism.

2. The shielding means that shields the space between the first space and the second space is a seal placed on the bearing. The gear apparatus according to claim 1.

3. The lubricant used in the first space does not contain Mo (molybdenum). The gear apparatus according to claim 1.

4. The sealing member is positioned on an eccentric shaft having an eccentric portion that causes the external gear to oscillate, or on a vibrating shaft having a vibrating body that causes the flexible external gear to flex and oscillate. The gear apparatus according to claim 1.

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