Deflection engagement type speed reduction device

Abstract

To provide a deflection engagement type speed reduction device that can restrain a decrease in detection accuracy of a sensor.SOLUTION: A deflection engagement type speed reduction device 100 comprises a flexible external gear 11, and an internal gear 16 engaged with the flexible external gear 11, comprises a sensor 5 capable of detecting deflection of the flexible external gear 11, on the flexible external gear 11, and comprises a labyrinth structure 7 for limiting a flow of a lubricant J between a space provided with the sensor 5, and a space inside external teeth of the flexible external gear 11.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a flexure engagement type reduction gear.

Background Art

[0002] A flexure engagement type reduction gear having a flexible external gear and an internal gear is known. For example, Patent Document 1 describes a harmonic gear device including an input member, a wave generator that rotates at the same rotational speed as the input member, a flexible external gear that is flexed into a non-circular shape by the wave generator, and an internal gear that meshes with the external gear. This device has a strain gauge as a sensor for detecting the torque applied to the gear, and also has a rubber seal member for preventing the adhesion of grease to the strain gauge.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The inventor has obtained the following new recognition regarding the flexure engagement type reduction gear. The harmonic gear device described in Patent Document 1 has a configuration in which the space of the sensor and the lubricant encapsulation space of the reduction gear are separated by a seal member. However, in this device, since the rubber seal member is in contact with the external gear, the detection accuracy of the sensor may be reduced due to the contact force of the seal member.

[0005] The present invention has been made in view of such problems, and one of the objects is to provide a flexure engagement type reduction gear capable of suppressing a decrease in the detection accuracy of the sensor.

Means for Solving the Problems

[0006] In order to solve the above problems, a flexure engagement type reduction gear according to an aspect of the present invention includes a flexible external gear and an internal gear that meshes with the flexible external gear. The flexible external gear has a sensor capable of detecting the flexure of the flexible external gear. It has a labyrinth structure that restricts the flow of lubricant between the space where the sensor is provided and the space inside the external teeth of the flexible external gear.

[0007] In addition, any combination of the above components, or those obtained by mutually substituting the components and expressions of the present invention between methods, systems, etc., are also effective as aspects of the present invention.

Advantages of the Invention

[0008] According to the present invention, it is possible to provide a flexure engagement type reduction gear that can suppress a decrease in the detection accuracy of the sensor.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0010] Hereinafter, the present invention will be described with reference to each drawing based on preferred embodiments. In the embodiments and modification examples, the same or equivalent components and members are denoted by the same reference numerals, and repeated explanations are omitted as appropriate. Also, the dimensions of the members in each drawing are appropriately enlarged or reduced for easy understanding. In addition, some members that are not important for explaining the embodiments in each drawing are omitted from the display.

[0011] Also, terms including ordinal numbers such as first and second are used to describe various components, but this term is used only for the purpose of distinguishing one component from another, and the components are not limited by this term.

[0012] [Embodiment] Referring to FIGS. 1 and 2, the overall configuration of a flexure engagement type reduction gear 100 (hereinafter sometimes referred to as "reduction gear 100") according to an embodiment will be described. FIG. 1 is a cross-sectional side view showing an example of the reduction gear 100. FIG. 2 is a side cross-sectional view showing a first example of a labyrinth structure.

[0013] The reduction gear 100 mainly includes an oscillating body shaft 20, an oscillating body 21, a flexible external gear 11, an internal gear 16, an oscillating body bearing 42, a carrier 35, a main bearing 37, oscillating body shaft bearings 39 and 40, casings 61 and 62, an output member 64, a sensor 5, and a labyrinth structure 7. Hereinafter, the direction along the central axis La of the internal gear 16 is referred to as the "axial direction", and the circumferential direction and the radial direction of a circle centered on the central axis La are referred to as the "circumferential direction" and the "radial direction", respectively. Also, the side where the output member 64 is provided with respect to the carrier 35 in the axial direction (the right side in the figure) is referred to as the output side, and the opposite side (the left side in the figure) is referred to as the anti-output side.

[0014] The reduction gear 100 has a reduction mechanism that decelerates the rotation input to the oscillating body shaft 20 from a power source such as a motor (not shown) and outputs it from the output member 64. The reduction gear 100 of the embodiment is a flexure engagement type reduction gear that causes the internal gear 16 to rotate by flexing the flexible external gear 11 that meshes with the internal gear 16 into a true circle and a non-true circle, and outputs the generated rotation component from the output member 64 to the driven member. The reduction gear 100 of the embodiment has a silk hat type flexible external gear 11.

[0015] The oscillation body shaft 20 is a shaft body that extends from the output side to the counter-output side in the axial direction and is rotated around the rotation center line La by the input rotation. The oscillation body shaft 20 in this example is a hollow shaft, but it may also be a solid shaft. On the outer periphery of the oscillation body shaft 20, a first shaft portion 22, an oscillation body 21, and a second shaft portion 26 are provided in order from the counter-output side to the output side. The first shaft portion 22 and the second shaft portion 26 support the inner rings of the oscillation body shaft bearings 39 and 40. The oscillation body 21 is a substantially elliptical portion having a larger diameter than the first shaft portion 22.

[0016] The first shaft portion 22 on the counter-output side of the oscillation body shaft 20 is supported by the first casing 61 via the oscillation body shaft bearing 39. The second shaft portion 26 on the output side of the oscillation body shaft 20 is supported by the output member 64 via the second oscillation body shaft bearing 40. That is, the oscillation body shaft 20 is rotatably supported with respect to the first casing 61 and the output member 64. The output member 64 is disposed on the side portion on the output side of the flexible external gear 11. The output member 64 is connected to the output sides of the carrier 35 and the internal gear 16 described later using bolts B2.

[0017] The first oscillation body shaft bearing 39 is disposed between the first casing 61 and the first shaft portion 22 of the oscillation body shaft 20. The second oscillation body shaft bearing 40 is disposed between the output member 64 and the second shaft portion 26 of the oscillation body shaft 20. As the oscillation body shaft bearings 39 and 40, various known bearing mechanisms can be adopted. In this example, the oscillation body shaft bearings 39 and 40 are ball bearings having spherical rolling elements.

[0018] The flexible external gear 11 is a thin substantially annular gear that can be elastically deformed. The flexible external gear 11 is rotatably supported around the central axis La. The flexible external gear 11 of the embodiment has external teeth 13, a diaphragm portion 14, and a fixing portion 15.

[0019] The external teeth 13 are formed on a body portion that extends in a cylindrical shape in the axial direction around the central axis La. The output-side end of the external teeth 13 is located radially outward of the vibration body 21 and radially inward of the internal gear 16. The diaphragm portion 14 is an annular portion that extends radially outward from the end of the external teeth 13 on the side opposite to the output side. The fixing portion 15 is an annular portion that extends further radially outward from the end of the diaphragm portion 14 on the radially outer side. The axial thickness of the fixing portion 15 is larger than the axial thickness of the diaphragm portion 14.

[0020] Since the external teeth 13 are flexible, they can be deformed in the radial direction. In particular, the output-side end of the external teeth 13 surrounded by the internal gear 16 is a free end, so it can be displaced more in the radial direction than other parts. On the other hand, the end of the external teeth 13 on the side opposite to the output side is a fixed end connected to the diaphragm portion 14 and the fixing portion 15, so it is more difficult to deform in the radial direction than the free end side. Also, as the external teeth 13 deform, the diaphragm portion 14 is slightly deflected and deformed in the axial direction, but the fixing portion 15 hardly deforms.

[0021] The external teeth 13 are pressed radially outward by the outer ring 422 of the oscillator bearing 42 of the oscillator 21 at two circumferential positions corresponding to the position of the major axis of the elliptical oscillator 21. As a result, one end of the external teeth 13 on one side in the axial direction is elastically deformed into an ellipse. As a result, at two circumferential positions corresponding to the major axis of the ellipse in the circumferential direction, the external teeth 13 mesh with the internal teeth 17 of the internal gear 16. Hereinafter, the circumferential position where the external teeth 13 and the internal teeth 17 mesh is referred to as the "meshing position".

[0022] The internal gear 16 is annular with the central axis La as the center. The internal gear 16 is fixed to the output member 64 for extracting the decelerated rotation and the carrier 35 by bolts B2. The internal gear 16 has internal teeth 17 that project on the inner circumferential side and mesh with the external teeth 13. A plurality of internal teeth 17 are arranged at a predetermined pitch in the circumferential direction. The number of internal teeth 17 is slightly (by 2 in this example) more than the number of external teeth 13. The rigidity of the internal teeth 17 of the internal gear 16 is much higher than the rigidity of the external teeth 13 of the flexible external gear 11. Therefore, the internal gear 16 can be regarded as a substantially rigid body.

[0023] The carrier 35 is a hollow annular member extending in a direction along the central axis La. The carrier 35 surrounds the external teeth 13 and is disposed on the output side of the diaphragm portion 14 and on the side portion of the non-output side of the internal gear 16. The carrier 35 is fixed to the internal gear 16 together with the output member 64. The carrier 35 is rotatably supported with respect to the second casing 62 via the main bearing 37.

[0024] The output member 64 is a hollow disk-shaped member surrounding the central axis La, and is fixed to the side portion of the output side of the internal gear 16 by bolts B2 and rotates integrally therewith. The output member 64 rotatably supports the output side of the vibrator shaft 20 via the second vibrator shaft bearing 40.

[0025] The main bearing 37 is disposed between the second casing 62 and the carrier 35. The main bearing 37 rotatably supports the carrier 35, the internal gear 16, and the output member 64 with respect to the second casing 62. The main bearing 37 can employ various known bearing mechanisms, and the main bearing 37 in this example is a cross roller bearing. The outer ring of the main bearing 37 is formed in the second casing 62 and does not have a dedicated outer ring. The inner ring of the main bearing 37 is formed in the carrier 35 and does not have a dedicated inner ring.

[0026] The casings 61, 62 function as the outer shell of the speed reducer 100. The casings 61, 62 include a disk-shaped first casing 61 that axially covers the non-output side of the carrier 35, and a cylindrical second casing 62 that is connected to the output side of the first casing 61. The first casing 61 surrounds the oil seal S1 and the vibrator shaft bearing 39. The first casing 61 is fixed, for example, by screwing to the frame of the device on which the speed reducer 100 is mounted.

[0027] A fixing portion 15 of the flexible external gear 11 is interposed between the output side of the first casing 61 and the non-output side of the second casing 62. These are provided with axially penetrating holes at the same position, and are connected by bolts B1 using these holes. A main bearing 37 and an oil seal S3 are arranged on the inner peripheral surface of the second casing 62. The second casing 62 surrounds the carrier 35 via the main bearing 37. The second casing 62 is rotatable with respect to the carrier 35.

[0028] The first oscillator shaft bearing 39 rotatably supports the non-output side of the oscillator shaft 20, and the second oscillator shaft bearing 40 rotatably supports the output side of the oscillator shaft 20. An oscillator shaft bearing 42 is arranged on the non-output side of the oscillator shaft bearing 40. Thereby, the oscillator shaft 20 rotates relative to the first casing 61, the second casing 62, and the flexible external gear 11.

[0029] The oscillator shaft bearing 42 is arranged between the oscillator 21 and the flexible external gear 11. The oscillator shaft bearing 42 in this example is a ball bearing having spherical rolling elements. The oscillator shaft bearing 42 rotatably supports the flexible external gear 11 and the oscillator 21. The oscillator shaft bearing 42 has an elliptical shape when viewed from the axial direction, similar to the oscillator 21. The oscillator shaft bearing 42 is displaceable in the radial direction according to the rotation of the oscillator 21. The oscillator shaft bearing 42 has an inner ring 421, an outer ring 422, and spherical rolling elements 423. The rolling elements may have, for example, a cylindrical shape different from a spherical shape.

[0030] A lubricant J is enclosed in the space where the first oscillator shaft bearing 39, the second oscillator shaft bearing 40, the oscillator shaft bearing 42, and the main bearing 37 are arranged. The lubricant J is sealed by oil seals S1, S2, and S3. The oil seal S1 is arranged on the non-output side of the first oscillator shaft bearing 39, the oil seal S2 is arranged on the output side of the second oscillator shaft bearing 40, and the oil seal S3 is arranged on the output side of the main bearing 37.

[0031] The deceleration operation of the deceleration device 100 will be described. When rotational power is transmitted to the oscillator shaft 20, the oscillator 21 rotates around the rotation center line passing through the oscillator shaft 20. When the oscillator 21 rotates, the major axis of the ellipse of the flexible external gear 11 rotates integrally. As a result, the meshing position between the external teeth 13 and the internal teeth 17 changes in the circumferential direction. Due to the difference between the number of external teeth 13 of the flexible external gear 11 and the number of internal teeth 17 of the internal gear 16, each time the oscillator 21 makes one rotation, the meshing position between the external teeth 13 and the internal teeth 17 changes slightly in the circumferential direction. As a result, the internal gear 16 rotates about the central axis La at a rotational speed lower than the rotational speed of the oscillator shaft 20. Therefore, a decelerated rotational motion can be extracted from the output member 64 that rotates integrally with the internal gear 16.

[0032] The sensor 5 will be described. The sensor 5 is a sensor that detects the deflection of the flexible external gear 11 in order to obtain the circumferential torque applied to the flexible external gear 11. The sensor 5 only needs to be able to detect the deflection of the flexible external gear 11, and various sensors based on known principles can be adopted. The sensor 5 in the embodiment is a sheet-like strain cage attached to the surface on the output side opposite to the diaphragm portion 14 of the flexible external gear 11. Since the strain cage is well-known, a detailed description thereof will be omitted. The sensor 5 may be arranged at a location other than the diaphragm portion 14 of the flexible external gear 11.

[0033] The strain cage of the embodiment has, for example, a metal thin film resistor formed on a flexible substrate. The resistor is configured such that its resistance value changes according to the circumferential deflection of the diaphragm portion 14. The strain cage can convert the change in the resistance value of the resistor into a voltage using a Wheatstone bridge circuit and extract it. The resistor of the strain cage may be provided over the entire circumference in the circumferential direction of the diaphragm portion 14, or may be provided in a part of the circumferential direction. As the sensor 5, the torque detection sensor described in Patent Document 1 can be adopted.

[0034] The detection signal of the sensor 5 is provided to a signal processing circuit (not shown). The signal processing circuit can calculate the direction and magnitude of the torque applied to the flexible external gear 11 based on the detection signal of the sensor 5.

[0035] When a lubricant adheres to the resistor of the strain gauge, the detection accuracy decreases due to its influence. For this reason, in the device described in Patent Document 1, in order to reduce the intrusion of the lubricant into the strain gauge, an annular seal member made of rubber or the like is arranged so as to contact the strain gauge. However, in this configuration, an external stress is applied to the strain gauge from the seal member, and there is a possibility that the detection accuracy of the strain gauge decreases due to the influence of the external stress. Therefore, the speed reduction device 100 of the embodiment has a labyrinth structure 7 that restricts the flow of the lubricant J between the space Q1 provided with the sensor 5 and the first space Q2 inside the external teeth 13 of the flexible external gear 11. With this configuration, the adhesion of the lubricant to the sensor 5 can be almost eliminated, and the decrease in the detection accuracy of the sensor 5 due to the influence of the external stress can be suppressed. The configuration of the labyrinth structure 7 is not particularly limited as long as it can restrict the flow of the lubricant J. Hereinafter, some configuration examples of the labyrinth structure 7 will be described with reference to FIGS. 2 to 5.

[0036] (First example) FIG. 2 is a side cross-sectional view showing a first example of the labyrinth structure 7. The labyrinth structure 7 of the embodiment includes a first labyrinth member 71 that restricts the outflow of the lubricant J from the oscillator bearing 42, and a second labyrinth member 72 that restricts the outflow of the lubricant from the first labyrinth member 71. In the embodiment, the first labyrinth member 71 is fixed to the outer ring 422 of the oscillator bearing 42, and the second labyrinth member 72 is fixed to, for example, the outer periphery of the first oscillator shaft bearing 39. The first labyrinth member 71 and the second labyrinth member 72 are formed from a thin plate material such as stainless steel and have a hollow cylindrical shape with a constant shape in the circumferential direction as a whole. The first labyrinth member 71 has a large-diameter cylindrical portion 714, an inner overhanging portion 715, a first tapered portion 711, a disk portion 712, and a small-diameter cylindrical portion 713.

[0037] The large-diameter cylindrical portion 714 is a cylindrical portion that surrounds the outer ring 422 of the oscillation body bearing 42. The large-diameter cylindrical portion 714 has an inner diameter slightly larger than the outer diameter of the outer ring 422 and surrounds from the end on the reaction force output side of the outer ring 422 to the vicinity of the end on the output side. The inner protruding portion 715 is a portion that protrudes radially inward from the output-side end of the large-diameter cylindrical portion 714 and fits into the outer peripheral groove 424 provided on the outer periphery of the outer ring 422. The inner protruding portion 715 regulates the axial position of the first labyrinth member 71. In this case, since the inner protruding portion 715 fits into the outer peripheral groove 424, axial displacement of the first labyrinth member 71 is less likely to occur.

[0038] The first tapered portion 711 extends toward the reaction force output side from the reaction force output-side end of the large-diameter cylindrical portion 714. The first tapered portion 711 has a reduced diameter as it moves away from the oscillation body bearing 42 and has a frustum shape in side view. The disk portion 712 is a portion that extends radially inward from the reaction force output-side end of the first tapered portion 711. The small-diameter cylindrical portion 713 is a cylindrical portion that extends toward the reaction force output side from the reaction force output-side end of the disk portion 712. The small-diameter cylindrical portion 713 forms a narrow cylindrical gap G1 on the outer peripheral surface of the oscillation body shaft 20.

[0039] In the first labyrinth member 71, when the lubricant J scattered from the oscillation body bearing 42 reaches the disk portion 712 and the first tapered portion 711, as indicated by the arrow, it moves to the output side of the first tapered portion 711 along the tapered surface of the first tapered portion 711 due to the centrifugal force accompanying the rotation of the oscillation body shaft 20. Further, the lubricant J leaking from the first space Q2 is almost captured by the narrow gap G1 of the small-diameter cylindrical portion 713 when moving through the small-diameter cylindrical portion 713.

[0040] The second labyrinth member 72 has a cylindrical portion 721, a circular plate portion 722, and a second tapered portion 723. The cylindrical portion 721 is a cylindrical part that surrounds the outer periphery of the first oscillation body shaft bearing 39. The cylindrical portion 721 extends from the end on the anti-output side of the first oscillation body shaft bearing 39 to the vicinity of the output side end. The circular plate portion 722 is a disk-shaped part that extends radially inward from the output side end of the cylindrical portion 721. The second tapered portion 723 extends toward the output side from the outer peripheral end of the circular plate portion 722. The second tapered portion 723 has a reduced diameter as it moves away from the first oscillation body shaft bearing 39 and has a frustum shape in side view. The second tapered portion 723 surrounds the small-diameter cylindrical portion 713 with a gap therebetween. That is, the second tapered portion 723 and the small-diameter cylindrical portion 713 overlap in the radial direction, and the second tapered portion 723 is located radially outside the small-diameter cylindrical portion 713.

[0041] In the second labyrinth member 72, when the lubricant scattered from the first oscillation body shaft bearing 39 reaches the second tapered portion 723, as shown by the arrow, it moves to the anti-output side of the second tapered portion 723 along the tapered surface of the second tapered portion 723 due to centrifugal force. Also, when the lubricant J scattered from the oscillation body bearing 42 leaks from the gap G1 to the second space Q3, due to centrifugal force, the lubricant J reaches the second tapered portion 723 and is captured in the second space Q3. Further, since the gap G2 between the second tapered portion 723 and the disk portion 712 is formed to be narrow, the flow of the lubricant J is restricted by this gap G2. Also, a narrow gap G3 is formed between the second tapered portion 723 and the external teeth 13, and the lubricant J that has leaked from the gap G2 is captured in this gap G3. Thus, the labyrinth structure 7 restricts the flow of the lubricant J by the action of each part.

[0042] (Second example) Referring to FIG. 3, a second example of the labyrinth structure 7 will be described. FIG. 3 is a side cross-sectional view showing the second example of the labyrinth structure 7. The second example is different from the first example in that it does not have the inner overhang portion 715 but has the stepped portion 716. Since the other configurations are the same, the differences will be mainly described and the overlapping descriptions will be omitted. The stepped portion 716 is a disc-shaped portion that projects radially inward from the anti-output side end of the large-diameter cylindrical portion 714 and abuts against the anti-output side end of the outer ring 422 of the vibration body bearing 42. With this configuration, the stepped portion 716 regulates the axial position of the first labyrinth member 71. The first tapered portion 711 extends from the inner end of the stepped portion 716 toward the anti-output side. In the second example of the labyrinth structure 7, the second labyrinth member 72 is the same as that in the first example. The second example of the labyrinth structure 7 has the same operations and effects as those in the first example. In addition, according to the second example, since the stepped portion 716 is position-regulated by the outer ring 422 of the bearing 42, it becomes difficult for the first labyrinth member 71 to move axially outward. Also, since no groove is provided on the outer periphery of the outer ring 422, the processing cost can be suppressed.

[0043] (Third example) Referring to FIG. 4, a third example of the labyrinth structure 7 will be described. FIG. 4 is a side cross-sectional view showing the third example of the labyrinth structure 7. The third example is different from the first example in that it does not have the large-diameter cylindrical portion 714 and the inner overhanging portion 715, but has the outer overhanging portion 717. Since the other configurations are the same, the differences will be mainly described and the overlapping descriptions will be omitted. The outer overhanging portion 717 is a portion that protrudes radially outward from the output-side end of the first tapered portion 711 and fits into the inner circumferential groove 425 provided on the inner circumference of the outer ring 422. The outer overhanging portion 717 regulates the axial position of the first labyrinth member 71. In the third example of the labyrinth structure 7, the second labyrinth member 72 is the same as that in the first example. The third example of the labyrinth structure 7 has the same operations and effects as the first example. In addition, according to the third example, since the outer overhanging portion 717 is positionally regulated by the inner circumferential groove 425, it becomes difficult for the first labyrinth member 71 to move on both axial sides. Also, since no extra member is interposed between the outer teeth 13 and the outer ring 422, the contact surface is reduced. Also, since no extra member is interposed, an increase in diameter in this portion can be avoided. Also, since the inner circumferential groove 425 is provided in a portion that has no relation to the rolling surface or the mating member, groove machining becomes easy.

[0044] (Fourth example) Referring to FIG. 5, a fourth example of the labyrinth structure 7 will be described. FIG. 5 is a side cross-sectional view showing the fourth example of the labyrinth structure 7. The fourth example is different from the third example in that it does not have the first tapered portion 711 and the small-diameter cylindrical portion 713, but has the intermediate cylindrical portion 718 and the diameter-expanded tapered portion 719. Since the other configurations are the same, the differences will be mainly described and the overlapping descriptions will be omitted. The intermediate cylindrical portion 718 is a cylindrical portion that extends from the inner circumferential end of the outer overhanging portion 717 toward the non-output side.

[0045] The diameter-expanded tapered portion 719 extends toward the anti-output side from the anti-output side end portion of the intermediate cylindrical portion 718. The diameter-expanded tapered portion 719 expands in a trumpet shape as it moves away from the vibration generating body bearing 42, and has a truncated cone shape in a side view. The diameter-expanded tapered portion 719 surrounds the second tapered portion 723 with a gap therebetween. That is, the diameter-expanded tapered portion 719 and the second tapered portion 723 overlap in the radial direction, and the second tapered portion 723 is located radially outside the diameter-expanded tapered portion 719. The diameter-expanded tapered portion 719 and the second tapered portion 723 may be substantially parallel. Since the gap G4 between the diameter-expanded tapered portion 719 and the second tapered portion 723 is configured to be narrow, the flow of the lubricant J is restricted by this gap G4. The fourth example of the labyrinth structure 7 exhibits the same actions and effects as the first example.

[0046] The features of the flexure engagement type reduction gear 100 of the embodiment will be described. The flexure engagement type reduction gear 100 has a flexible external gear 11 and an internal gear 16 that meshes with the flexible external gear 11. The flexible external gear 11 has a sensor 5 capable of detecting the flexure of the flexible external gear 11, and has a labyrinth structure 7 that restricts the flow of the lubricant J between the space Q1 provided with the sensor 5 and the first space Q2 inside the external teeth of the flexible external gear 11.

[0047] According to this configuration, since it has the labyrinth structure 7, the intrusion of the lubricant J into the space Q1 is restricted, and a decrease in the detection accuracy of the sensor 5 due to the adhesion of the lubricant J can be suppressed. Further, since the labyrinth structure 7 does not generate external stress, a decrease in the detection accuracy of the sensor 5 due to external stress can be suppressed.

[0048] As an example, the flexible external gear 11 has external teeth 13 that mesh with the internal gear 16 and a diaphragm portion 14 that extends radially on the axial side portion side of the external teeth 13, and the sensor 5 is provided on the diaphragm portion 14. In this case, since the diaphragm portion 14 is flat, it is easy to attach the sensor 5.

[0049] As an example, the flexure engagement type reduction gear 100 has an oscillator 21 and an oscillator bearing 42 provided between the oscillator 21 and the flexible external gear 11, and has a first labyrinth member 71 that restricts the outflow of the lubricant from the oscillator bearing 42 and a second labyrinth member 72 that restricts the outflow of the lubricant from the first labyrinth member 71. In this case, since two labyrinth members are used, the outflow path of the lubricant can be configured as a complex maze, and the outflow amount can be further reduced.

[0050] As an example, the first labyrinth member 71 includes a first tapered portion 711 whose diameter decreases as it moves away from the oscillator bearing 42. In this case, since the lubricant scattered from the oscillator bearing 42 is collected by the first tapered portion 711, the diffusion of the lubricant can be suppressed.

[0051] As an example, the first labyrinth member 71 is fixed to the outer ring 422 of the oscillator bearing 42. In this case, since the first labyrinth member 71 can cover the entire reaction output side of the oscillator bearing 42, the lubricant scattered from the oscillator bearing 42 can be efficiently captured.

[0052] As an example, the second labyrinth member 72 includes a second tapered portion 723 whose diameter decreases as it moves away from the oscillator shaft bearing 39 that supports the oscillator shaft 20 on which the oscillator 21 is provided. In this case, since the lubricant scattered from the oscillator shaft bearing 39 is collected by the second tapered portion 723, the diffusion of the lubricant can be suppressed.

[0053] As an example, the first labyrinth member 71 and the second labyrinth member 72 overlap in the radial direction, and the second labyrinth member 72 is located radially outside the first labyrinth member 71 side. In this case, by narrowing the overlapping portion of the first labyrinth member 71 and the second labyrinth member 72 in the radial direction, the movement of the lubricant can be restricted at that portion.

[0054] The present invention has been described based on the embodiments. These embodiments are illustrative, and it is 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 such modifications and changes are also within the scope of the claims of the present invention. Therefore, the descriptions and drawings in this specification should be treated as illustrative rather than restrictive.

[0055] (Modification example) Hereinafter, modification examples will be described. In the drawings and descriptions of the modification examples, the same reference numerals are given to the components and members that are the same as or equivalent to those in the embodiments. Descriptions that overlap with the embodiments will be omitted as appropriate, and the configurations different from the embodiments will be mainly described.

[0056] In the description of the embodiment, an example where the reduction gear 100 is a top hat type reduction gear is shown, but the present invention is not limited to this. For example, the reduction gear may be a non-top hat type flexure engagement type reduction gear such as a cylindrical type or a cup type.

[0057] In the description of the embodiment, an example where the labyrinth structure 7 has a first labyrinth member 71 and a second labyrinth member 72 is shown, but the present invention is not limited to this. For example, either one of the first labyrinth member and the second labyrinth member may not be provided.

[0058] In the description of the embodiment, an example where the number of the oscillating bodies 21 is 1 is shown, but the present invention is not limited to this. The number of the oscillating bodies may be 2 or more.

[0059] In the description of the embodiment, an example where the oscillating body bearing 42 is a ball bearing is shown, but the present invention is not limited to this. The oscillating body bearing may be a roller bearing or the like.

[0060] In the description of the embodiment, an example where the main bearing 37 is a cross roller bearing is shown, but the present invention is not limited to this. The main bearing may be a bearing of a type different from the cross roller bearing, such as an angular ball bearing or an angular roller bearing.

[0061] In the description of the embodiment, an example in which the oscillation body shaft bearings 39 and 40 are ball bearings has been shown, but the present invention is not limited to this. The oscillation body shaft bearings may be bearings of a type different from ball bearings, such as roller bearings.

[0062] Each of these modifications has the same operations and effects as the embodiment.

[0063] Any combination of the above-described embodiments and modifications is also useful as an embodiment of the present invention. The new embodiment resulting from the combination has the effects of the embodiments and modifications combined.

Description of Reference Numerals

[0064] Q1, Q2, Q3 spaces, 7 labyrinth structure, 11 flexible external gear, 13 external teeth, 14 diaphragm portion, 15 fixing portion, 16 internal gear, 17 internal teeth, 21 oscillation body, 35 carrier, 39 first oscillation body shaft bearing, 40 second oscillation body shaft bearing, 42 oscillation body bearing, 71 first labyrinth member, 72 second labyrinth member, 422 outer ring, 711 first taper portion, 723 second taper portion, 100 flexural engagement type reduction gear.

Claims

1. A flexible external gear and an internal gear meshing with the flexible external gear, wherein the flexible external gear has a sensor capable of detecting the deflection of the flexible external gear, and a deflection meshing type reduction gear having a labyrinth structure for restricting the flow of lubricant between the space where the sensor is provided and the space inside the external teeth of the flexible external gear.

2. The flexible external gear has external teeth meshing with the internal gear and a diaphragm portion extending radially on the axial side portion of the external teeth, and the sensor is provided on the diaphragm portion. The deflection meshing type reduction gear according to Claim 1.

3. It has an oscillating body and an oscillating body bearing provided between the oscillating body and the flexible external gear, wherein the labyrinth structure has a first labyrinth member for restricting the outflow of lubricant from the space including the oscillating body bearing to the first space side, and a second labyrinth member for restricting the outflow of lubricant from the first space to the space where the sensor is provided. The deflection meshing type reduction gear according to Claim 1.

4. The first labyrinth member includes a first tapered portion whose diameter decreases as it moves away from the oscillating body bearing. The deflection meshing type reduction gear according to Claim 3.

5. The first labyrinth member is fixed to the outer ring of the oscillating body bearing. The deflection meshing type reduction gear according to Claim 3.

6. The second labyrinth member includes a second tapered portion whose diameter decreases as it moves away from the oscillating body shaft bearing that supports the oscillating body shaft where the oscillating body is provided. The deflection meshing type reduction gear according to Claim 3.

7. The first labyrinth member and the second labyrinth member overlap in the radial direction, and the second labyrinth member is located radially outside the first labyrinth member side. The deflection meshing type reduction gear according to Claim 3.

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