Harmonic Reducer and Industrial Robot

Abstract

A harmonic reducer (100) and an industrial robot. The harmonic reducer (100) includes: a shaft (4) including a first through hole (403), the first through hole extending from a first end (401) of the shaft (4) to a second end (402) along an axial direction (X) of the shaft (4); a wave generator (13) arranged on the shaft (4), the wave generator being capable of rotating together with the shaft (4); a flexible wheel (11) arranged around the wave generator (13); a rigid wheel (12) arranged around the flexible wheel (11); a first flange (21), the first flange being coupled to the shaft (4) via a first bearing (31) and coupled to the flexible wheel (11); and a second flange (22), the second flange being coupled to the shaft (4) via a second bearing (32) and coupled to the rigid wheel (12), wherein one of the first flange (21) and the second flange (22) is arranged close to the first end (401) of the shaft (4), and wherein a cavity (5) is provided between one of the first flange (21) and the second flange (22) and the first end (401) of the shaft (4), the cavity being in fluid communication with the external environment via the first through hole (403). According to various embodiments of the present disclosure, leakage of lubricant via the oil seal of the harmonic reducer (100) can be effectively prevented.

Description

Technical Field

[0001] Embodiments of the present disclosure mainly relate to the field of speed reducers, and more particularly, to a harmonic speed reducer and an industrial robot. Background Art

[0002] Due to its small size, light weight, and high precision, the harmonic speed reducer is widely used in the drive of various devices or machines such as industrial robots, power tools, and automobiles. A traditional harmonic speed reducer includes three basic components: a flexible gear, a rigid gear, and a wave generator. During the operation of the harmonic speed reducer, the wave generator can rotate to cause the flexible gear to generate a controllable elastic deformation and mesh with the rigid gear. In this way, the harmonic speed reducer can achieve the transmission of motion and power.

[0003] Generally, a lubricant is provided inside the harmonic speed reducer to reduce the friction between the components of the harmonic speed reducer. During the operation of the harmonic speed reducer, due to various reasons (such as temperature rise and lubricant evaporation caused by temperature rise), high pressure may accumulate in the internal space of the harmonic speed reducer. The accumulation of internal pressure may cause the lubricant to pass through the oil seal of the harmonic speed reducer and leak from the harmonic speed reducer. For example, in the case of using a harmonic speed reducer to drive an industrial robot joint, the leakage of the lubricant may reduce the lubrication performance of the harmonic speed reducer and contaminate the robot and the workpiece processed by the robot.

[0004] Traditionally, in order to prevent such internal pressure accumulation, a vent hole blocked by a plug can be provided on the harmonic speed reducer. In this arrangement, when the internal pressure of the harmonic speed reducer increases, the operator can open the plug to release the gas inside the harmonic speed reducer. For example, the operator can open the plug to release the gas after the harmonic speed reducer is preheated. However, during the operation of a device (such as an industrial robot) including a harmonic speed reducer, the operator will not be able to open the plug on the harmonic speed reducer to release the high-pressure gas. In addition, the manual operation by the operator on the harmonic speed reducer may cause harm to the operator.

[0005] Therefore, a solution that can prevent the internal pressure accumulation and lubricant leakage of the harmonic speed reducer is needed. Summary of the Invention

[0006] In view of the above problems, various exemplary embodiments of the present disclosure provide a harmonic speed reducer that can prevent internal pressure accumulation and lubricant leakage.

[0007] In a first aspect of the present disclosure, example embodiments of the present disclosure provide a harmonic reducer. The harmonic reducer includes: a shaft having a first through hole, the first through hole extending from a first end of the shaft to a second end along an axial direction of the shaft; a wave generator disposed on the shaft, the wave generator being capable of rotating together with the shaft; a flexible wheel disposed around the wave generator; a rigid wheel disposed around the flexible wheel; a first flange, the first flange being coupled to the shaft via a first bearing and coupled to the flexible wheel; and a second flange, the second flange being coupled to the shaft via a second bearing and coupled to the rigid wheel, wherein one of the first flange and the second flange is disposed close to the first end of the shaft, and wherein a cavity is provided between one of the first flange and the second flange and the first end of the shaft, and the cavity is in fluid communication with the external environment via the first through hole.

[0008] In some embodiments, the harmonic reducer further includes a porous material disposed in the first through hole.

[0009] In some embodiments, the harmonic reducer further includes a sealing mechanism configured to selectively allow the cavity to be in fluid communication with the external environment via the first through hole according to the internal pressure of the cavity.

[0010] In some embodiments, the sealing mechanism includes: a base element coupled to the first end of the shaft and including a second through hole in fluid communication with the first through hole; a first sealing element disposed on the base element and including one or more openings and a sealing surface around the one or more openings, the one or more openings being configured to communicate the cavity with the second through hole; and a second sealing element disposed between the first sealing element and the base element and including an elastic sealing lip configured to contact the sealing surface of the first sealing element to block the communication between the cavity and the second through hole when the internal pressure of the cavity is lower than a pressure threshold, and configured to be pushed away from the sealing surface of the first sealing element to enable the cavity to communicate with the second through hole when the internal pressure of the cavity is higher than the pressure threshold.

[0011] In some embodiments, the base element includes: a mounting portion inserted into the first through hole at the first end of the shaft, the second through hole being provided on the mounting portion; and a receiving portion including a first receiving space, a second receiving space, and a step between the first receiving space and the second receiving space, the second receiving space being closer to the mounting portion than the first receiving space.

[0012] In some embodiments, the first sealing element further includes: a sealing portion disposed in the first receiving space and supported by the step, the one or more openings and the sealing surface being provided on the sealing portion; and a mounting post coupled to the sealing portion and configured to mount the second sealing element.

[0013] In some embodiments, the second sealing element further includes: a support portion configured to support the elastic sealing lip and including a mounting hole into which the mounting post of the first sealing element is inserted.

[0014] In some embodiments, the base element further includes a groove at its outer surface.

[0015] In some embodiments, the sealing mechanism includes: a second sealing element disposed at the second end of the shaft and including an elastic sealing lip configured to contact the second end of the shaft to block communication between the first through hole and the external environment when the internal pressure of the cavity is lower than the pressure threshold, and configured to be pushed away from the second end of the shaft to enable communication between the first through hole and the external environment when the internal pressure of the cavity is higher than the pressure threshold.

[0016] In some embodiments, the second sealing element further includes: a support portion configured to support the elastic sealing lip and including a mounting hole.

[0017] In some embodiments, the harmonic reducer further includes a pulley disposed on the shaft near the second end of the shaft and capable of rotating with the shaft, wherein the sealing mechanism further includes a second base element configured to support the second sealing element and including: a pair of mounting portions coupled to the pulley; and a second mounting post inserted into the mounting hole of the second sealing element to fix the support portion of the second sealing element.

[0018] In some embodiments, the harmonic reducer further includes one or more channels disposed between one of the first flange and the second flange and the corresponding one of the first bearing and the second bearing.

[0019] In some embodiments, the harmonic reducer further includes a bearing sleeve disposed around the corresponding one of the first bearing and the second bearing.

[0020] In some embodiments, the harmonic reducer further includes a crossed roller bearing including an outer ring coupled to the flexspline and an inner ring coupled to the rigid spline.

[0021] In a second aspect of the present disclosure, example embodiments of the present disclosure provide an industrial robot including a harmonic reducer according to the first aspect of the present disclosure.

[0022] According to various embodiments of the present disclosure, the cavity inside the harmonic reducer can be in fluid communication with the external environment via a first through hole in the shaft. When the temperature of the harmonic reducer rises, the gas inside the harmonic reducer can be released to the external environment via the first through hole, so that the internal pressure of the harmonic reducer can be maintained at a low level. In this way, it is possible to effectively prevent the lubricant from leaking through the oil seal of the harmonic reducer.

[0023] In addition, during the operation of the harmonic reducer, the rotation of the shaft causes the lubricant (if any) adhering to the shaft to be subjected to centrifugal force. Under the action of the centrifugal force, the lubricant flies off the shaft during the high-speed rotation of the shaft. In this way, it is possible to largely prevent the lubricant from leaking from the harmonic reducer through the first through hole in the shaft.

[0024] In addition, according to some embodiments of the present disclosure, a sealing mechanism is provided in the harmonic reducer to selectively allow the cavity to be in fluid communication with the external environment through the first through hole. When the internal pressure of the cavity is lower than the pressure threshold, the sealing mechanism blocks the communication between the cavity and the external environment. When the internal pressure of the cavity is higher than the pressure threshold, the sealing mechanism allows the cavity to communicate with the external environment. In this way, the internal pressure of the harmonic reducer can be maintained at a low level. In addition, it is possible to further prevent the lubricant from leaking out of the harmonic reducer through the first through hole of the shaft. In addition, the sealing mechanism can prevent debris in the external environment from entering the harmonic reducer through the first through hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and other objects, features, and advantages of the exemplary embodiments disclosed herein will become more readily understood through the following detailed description in conjunction with the accompanying drawings. In the drawings, several exemplary embodiments disclosed herein will be shown by way of example and not limitation, wherein:

[0026] Figure 1 A cross-sectional view of a harmonic reducer according to a first embodiment of the present disclosure is shown;

[0027] Figure 2 A cross-sectional view of a harmonic reducer according to a second embodiment of the present disclosure is shown;

[0028] Figure 3 A cross-sectional view of a harmonic reducer according to a third embodiment of the present disclosure is shown;

[0029] Figure 4 is Figure 3 A partial enlarged view of the harmonic reducer shown;

[0030] Figure 5 is Figure 3 An exploded view of the sealing mechanism of the harmonic reducer shown;

[0031] Figure 6 When viewed in another direction, Figure 5 An exploded view of the sealing mechanism shown;

[0032] Figure 7 A cross-sectional view of a harmonic reducer according to a fourth embodiment of the present disclosure is shown;

[0033] Figure 8 is Figure 7 A partial enlarged view of the harmonic reducer shown;

[0034] Figure 9 is Figure 7 an exploded view of the sealing mechanism of the harmonic reducer shown;

[0035] Figure 10 showing a cross-sectional view of a harmonic reducer according to a fifth embodiment of the present disclosure;

[0036] Figure 11 showing a cross-sectional view of a harmonic reducer according to a sixth embodiment of the present disclosure;

[0037] Figure 12 is Figure 11 a perspective view of the first flange of the harmonic reducer shown;

[0038] Figure 13 showing Figure 11 the relative arrangement of the first flange and the first bearing of the harmonic reducer shown;

[0039] Figure 14 showing a cross-sectional view of a harmonic reducer according to a seventh embodiment of the present disclosure;

[0040] Figure 15 is Figure 14 a partially enlarged view of the harmonic reducer shown; and

[0041] Figure 16 is Figure 14 a perspective view of the second base element of the harmonic reducer shown.

[0042] Throughout the drawings, the same or similar reference numerals are used to denote the same or similar elements. Detailed Description of the Invention

[0043] Now, the principles of the present disclosure will be described with reference to several exemplary embodiments shown in the drawings. Although exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the purpose of describing these embodiments is only to enable those skilled in the art to better understand and thereby implement the present disclosure, and is not intended to limit the scope of the present disclosure in any way.

[0044] The term "comprising" or "including" and its variants shall be understood as open terms, meaning "including but not limited to". The term "or" shall be construed as "and / or", unless explicitly stated otherwise in the context. The term "based on" shall be understood as "at least partially based on". The term "operable to" represents a function, action, movement, or state that can be achieved by an operation caused by a user or an external agency. The terms "an embodiment" and "embodiment" shall be understood as "at least one embodiment". The term "another embodiment" shall be understood as "at least one other embodiment". The terms "first", "second", etc. may refer to different or the same objects. Other definitions (explicit and implicit) may be included hereinafter. Unless explicitly stated otherwise in the context, the definitions of the terms are consistent throughout the specification.

[0045] Unless otherwise stated or limited, the terms "mounted", "connected", "supported", and "coupled" and their variants are used broadly and include direct and indirect mounting, connection, support, and coupling. Further, "connected" and "coupled" are not limited to physical or mechanical connection or coupling. In the following description, the same reference numerals and labels are used to describe the same, similar, or corresponding parts in the drawings. Other definitions (explicit and implicit) may be included hereinafter.

[0046] As described above, the internal pressure accumulation in the harmonic reducer may cause the lubricant to leak from the harmonic reducer through the oil seal. According to an embodiment of the present disclosure, in order to prevent the internal pressure accumulation and lubricant leakage in the harmonic reducer, a through hole is provided in the shaft of the harmonic reducer so that the cavity in the harmonic reducer can be in fluid communication with the external environment. As will be described in detail in the following paragraphs, the above concept can be implemented in various ways.

[0047] The principles of the present disclosure will be described in detail below in conjunction with Figures 1 to 16 First, refer to Figure 1 , Figure 1 which shows a cross-sectional view of a harmonic reducer according to a first embodiment of the present disclosure. As Figure 1 shown, the harmonic reducer 100 generally includes a shaft 4, a wave generator 13, a flexible gear 11, a rigid gear 12, a first flange 21, and a second flange 22.

[0048] The shaft 4 is an input shaft of the harmonic reducer 100 and is adapted to receive a driving force (torque) input from a driver such as a motor. As Figure 1 shown, the shaft 4 includes a first end 401 and a second end 402 opposite to the first end 401. The first end 401 is disposed inside the harmonic reducer 100, and the second end 402 is disposed outside the harmonic reducer 100. The shaft 4 is provided with a first through hole 403 that extends along the axial direction X of the shaft 4 from the first end 401 to the second end 402.

[0049] The wave generator 13 is arranged on the shaft 4 and can rotate together with the shaft 4. That is to say, the wave generator 13 can rotate synchronously with the shaft 4. The flexible gear 11 is arranged around the wave generator 13. The rigid gear 12 is arranged around the flexible gear 11. During the operation of the harmonic speed reducer 100, the wave generator 13 can rotate to cause the flexible gear 11 to generate a controllable elastic deformation and mesh with the rigid gear 12. The number of teeth of the rigid gear 12 is two more than that of the flexible gear 11. With this arrangement, the harmonic speed reducer 100 can achieve the transmission of motion and power. It should be noted that the structures and operating principles of the wave generator 13, the flexible gear 11, and the rigid gear 12 are known in the art and will not be described in detail herein.

[0050] The first flange 21 is coupled to the shaft 4 via the first bearing 31. The second flange 22 is coupled to the shaft 4 via the second bearing 32. With this arrangement, the shaft 4 can be supported by the first flange 21 and the second flange 22. In addition, the first flange 21 is also coupled to the flexible gear 11, and the second flange 22 is also coupled to the rigid gear 12. During the operation of the harmonic speed reducer 100, the flexible gear 11 can rotate synchronously at a low speed together with the first flange 21, while the rigid gear 12 and the second flange 22 do not rotate.

[0051] In the first embodiment, as Figure 1 shown, the first end 401 of the shaft 4 is arranged inside the harmonic speed reducer 100 and is close to the first flange 21. A cavity 5 is provided between the first flange 21 and the first end 401 of the shaft 4. The cavity 5 is in fluid communication with the internal space 9 of the harmonic speed reducer 100 via a gap, for example, on the first bearing 31. Therefore, the cavity 5 and the internal space 9 of the harmonic speed reducer 100 can have substantially the same pressure. In addition, the cavity 5 is in fluid communication with the external environment via the first through hole 403. When the pressure inside the harmonic speed reducer 100 rises due to, for example, a temperature increase, the gas inside the harmonic speed reducer 100 can be released to the external environment via the first through hole 403.

[0052] To reduce the friction between the components of the harmonic speed reducer 100, a lubricant is usually provided in the internal space 9 of the harmonic speed reducer 100. During the operation of the harmonic speed reducer 100, if the temperature of the harmonic speed reducer 100 rises, the gas in the internal space 9 can be released into the cavity 5 and then released to the external environment via the first through hole 403, so that the pressure of the internal space 9 can be maintained at a low level. In this way, it is possible to effectively prevent the lubricant from leaking through the oil seal 81 of the harmonic speed reducer 100.

[0053] In addition, during the operation of the harmonic reducer 100, the rotation of the shaft 4 causes the lubricant (if any) adhering to the shaft 4 to be subjected to centrifugal force. Under the action of the centrifugal force, the lubricant flies off the shaft 4 during the high-speed rotation of the shaft 4. In this way, it is possible to largely prevent the lubricant from leaking from the harmonic reducer 100 via the first through hole 403.

[0054] In the first embodiment, as Figure 1 shown, the harmonic reducer 100 further includes a crossed roller bearing 14. The crossed roller bearing 14 includes an outer ring 141 coupled to the flexible gear 11 and an inner ring 142 coupled to the rigid gear 12. In other embodiments, the crossed roller bearing 14 may be replaced by other types of bearings. The scope of the present disclosure is not intended to be limited in this regard.

[0055] Figure 2 A cross-sectional view of a harmonic reducer according to a second embodiment of the present disclosure is shown. Figure 2 The structure of the harmonic reducer 100 shown is similar to that of the harmonic reducer 100 shown Figure 1 but Figure 2 the harmonic reducer 100 shown further includes a porous material 404 disposed in the first through hole 403. The porous material 404 is breathable but impermeable to lubricant. Therefore, on the one hand, the porous material 404 can adsorb the lubricant mixed in the gas from the cavity 5, and on the other hand, it can prevent debris in the external environment from entering the cavity 5 via the first through hole 403.

[0056] Figure 3 A cross-sectional view of a harmonic reducer according to a third embodiment of the present disclosure is shown. Figure 3 The structure of the harmonic reducer 100 shown is similar to that of the harmonic reducer 100 shown Figure 1 but Figure 3 the harmonic reducer 100 shown further includes a sealing mechanism 6. The sealing mechanism 6 is configured to selectively allow the cavity 5 to be in fluid communication with the external environment according to the internal pressure of the cavity 5. When the internal pressure of the cavity 5 increases due to the temperature rise of the harmonic reducer 100, the sealing mechanism 6 can allow the cavity 5 to communicate with the external environment. Conversely, when the internal pressure of the cavity 5 is substantially the same as the ambient pressure, the sealing mechanism 6 can block the communication between the cavity 5 and the external environment.

[0057] The sealing mechanism 6 can have various structures. Figures 4 to 6 An exemplary structure and arrangement of the sealing mechanism 6 are shown. As Figures 4 to 6 shown, the sealing mechanism 6 includes a base element 60, a first sealing element 61, and a second sealing element 62.

[0058] As Figures 4 to 6As shown, the base element 60 is arranged at the first end 401 of the shaft 4 and is adapted to support the first sealing element 61 and the second sealing element 62. In some cases, the base element 60 can be detachably mounted to the shaft 4, for example, by screws or otherwise. In other cases, the base element 60 can be welded to the first end 401 of the shaft 4 or even formed as part of the shaft 4.

[0059] In some embodiments, as Figure 5 and Figure 6 shown, the base element 60 includes a mounting portion 601 adapted to be mounted to the shaft 4 and a receiving portion 602 adapted to receive the first sealing element 61 and the second sealing element 62. A second through hole 603 in fluid communication with the first through hole 403 is provided on the mounting portion 601. The mounting portion 601 can be inserted into the first through hole 403 of the shaft 4 and coupled to the shaft 4 by screws or interference fit or in various other ways. The receiving portion 602 includes a first receiving space 604, a second receiving space 605, and a step 606 between the first receiving space 604 and the second receiving space 605. The second receiving space 605 is in fluid communication with the second through hole 603 and thus in fluid communication with the first through hole 403. The second receiving space 605 is closer to the mounting portion 601 than the first receiving space 604. That is, the second receiving space 605 is provided at the lower part of the receiving portion 602, and the first receiving space 604 is provided at the upper part of the receiving portion 602. The first sealing element 61 and the second sealing element 62 are arranged in the first receiving space 604 and the second receiving space 605, as will be described in detail below.

[0060] As Figures 4 to 6 shown, the first sealing element 61 is arranged on the base element 60 and includes one or more openings 613 and a sealing surface 614 surrounding the one or more openings 613. The one or more openings 613 are configured to put the cavity 5 in communication with the second through hole 603. The sealing surface 614 is configured to cooperate with the second sealing element 62. When the sealing surface 614 contacts the second sealing element 62, the one or more openings 613 will be closed, and when the sealing surface 614 does not contact the second sealing element 62, the one or more openings 613 will be opened.

[0061] In some embodiments, as Figures 4 to 6 shown, the first sealing element 61 includes a sealing portion 611 and a mounting post 612. The sealing portion 611 is arranged in the first receiving space 604 and is supported by the step 606. The sealing portion 611 can be adhered to the receiving portion 602 or fixed in the first receiving space 604 by interference fit. The one or more openings 613 and the sealing surface 614 are provided on the sealing portion 611. The sealing surface 614 is part of the bottom surface of the sealing portion 611. The mounting post 612 is adapted to mount the second sealing element 62.

[0062] As Figures 4 to 6 shown, a second sealing element 62 is disposed between the first sealing element 61 and the base element 60 to selectively permit or block fluid communication between the cavity 5 and the first through hole 403 of the shaft 4. The second sealing element 62 is generally located within the second receiving space 605. To cooperate with the sealing surface 614 of the first sealing element 61, the second sealing element 62 includes an elastic sealing lip 622. The elastic sealing lip 622 is configured to contact the sealing surface 614 of the first sealing element 61 when the internal pressure of the cavity 5 is lower than a pressure threshold to block the communication between the cavity 5 and the second through hole 603, and is configured to be pushed away from the sealing surface 614 of the first sealing element 61 when the internal pressure of the cavity 5 is higher than the pressure threshold to enable the cavity 5 to communicate with the second through hole 603.

[0063] In some embodiments, as Figures 4 to 6 shown, the elastic sealing lip 622 is formed on a support portion 621. The support portion 621 is configured to support the elastic sealing lip 622 and includes a mounting hole 623 into which the mounting post 612 of the first sealing element 61 is inserted. Through the cooperation between the mounting post 612 and the mounting hole 623, the second sealing element 62 can be easily and reliably coupled to the first sealing element 61.

[0064] In some embodiments, the second sealing element 62 may be integrally made of a rubber material or other elastic material. In some other embodiments, only the elastic sealing lip 622 is made of a rubber material or other elastic material, and the elastic sealing lip 622 is coupled to the support portion 621 made of a different material.

[0065] According to an embodiment of the present disclosure, the sealing mechanism 6 can provide additional advantages. On the one hand, the internal pressure of the harmonic reducer 100 can be maintained at a low level. On the other hand, through the cooperation between the sealing surface 614 of the first sealing element 61 and the elastic sealing lip 622 of the second sealing element 62, the opening 613 on the first sealing element 61 can be blocked most of the time. Therefore, it is possible to further prevent the lubricant from leaking out of the harmonic reducer 100 through the first through hole 403 of the shaft 4, and the sealing mechanism 6 can prevent debris in the external environment from entering the harmonic reducer 100 through the first through hole 403.

[0066] Figure 7 A cross-sectional view of a harmonic reducer according to a fourth embodiment of the present disclosure is shown. Figure 7 The structure of the harmonic reducer 100 shown is similar to that of the harmonic reducer 100 shown in Figure 3 but the base element 60 further includes a groove 607 at its outer surface. Figure 8 and Figure 9Details of the groove 607 are shown. As shown, the groove 607 is arranged at the outer surface of the receiving portion 602 of the base element 60. The groove 607 includes a bottom surface and two inclined side walls. The inclined side walls of the groove 607 will make it easier for the lubricant adhering to the base element 60 to fly off the base element 60.

[0067] Figure 10 A cross-sectional view of a harmonic reducer according to a fifth embodiment of the present disclosure is shown. Figure 10 The structure of the harmonic reducer 100 shown is similar to Figure 7 the structure of the harmonic reducer 100 shown, but Figure 10 the harmonic reducer 100 shown further includes a pulley 70 arranged on the shaft 4. The pulley 70 is arranged close to the second end 402 of the shaft 4 and can rotate together with the shaft 4. By providing the pulley 70, the shaft 4 of the harmonic reducer 100 can be driven by a driver via a belt.

[0068] In some cases, a large amount of lubricant may accumulate in the cavity 5. To remove the lubricant in the cavity 5, one or more channels can be provided between the cavity 5 and the internal space 9. Figures 11 to 13 An example method for removing the lubricant in the cavity 5 is shown.

[0069] Figure 11 A cross-sectional view of a harmonic reducer according to a sixth embodiment of the present disclosure is shown, Figure 12 is Figure 11 a perspective view of the first flange of the harmonic reducer shown, and Figure 13 shows Figure 11 the relative arrangement of the first flange and the first bearing of the harmonic reducer shown. Figure 11 The structure of the harmonic reducer 100 shown is similar to Figure 10 the structure of the harmonic reducer 100 shown, but the harmonic reducer 100 further includes one or more channels 210 arranged between the first flange 21 and the first bearing 31. Through the channels 210, the lubricant in the cavity 5 can flow back into the internal space 9.

[0070] In some embodiments, as Figures 11 to 13 shown, the harmonic reducer 100 further includes a bearing sleeve 71 arranged around the first bearing 31. The bearing sleeve 71 can protect the first bearing 31 from being worn by the first flange 21.

[0071] Figure 14 A cross-sectional view of a harmonic reducer according to a seventh embodiment of the present disclosure is shown, Figure 15 is Figure 14 a partially enlarged view of the harmonic reducer shown, and Figure 16 is Figure 14 a perspective view of the second base element of the harmonic reducer shown.Figure 14 The structure of the harmonic reducer 100 shown Figure 10 is similar to that of the harmonic reducer 100 shown, but Figure 14 the sealing mechanism 6 shown has a different structure and is arranged at a different position.

[0072] As Figure 14 and Figure 15 shown, the sealing mechanism 6 includes a second sealing element 62. Figure 14 and Figure 15 The structure of the second sealing element 62 shown Figures 4 to 6 is similar to that of the second sealing element 62 shown. For example, the second sealing element 62 includes an elastic sealing lip 622 and a support portion 621, and the support portion 621 is adapted to support the elastic sealing lip 622. The elastic sealing lip 622 is configured to contact the second end 402 of the shaft 4 when the internal pressure of the cavity 5 is lower than the pressure threshold to block the communication between the first through hole 403 and the external environment, and is configured to be pushed away from the second end 402 of the shaft 4 when the internal pressure of the cavity 5 is higher than the pressure threshold to enable the communication between the first through hole 403 and the external environment.

[0073] In some embodiments, in order to fix the second sealing element 62 at the second end 402 of the shaft 4, the sealing mechanism 6 further includes a second base element 63, and the second base element 63 is configured to support the second sealing element 62. As Figure 15 and Figure 16 shown, the second base element 63 includes a second mounting post 632 and a pair of mounting portions 631. The mounting portion 631 is coupled to the pulley 70. The second mounting post 632 is inserted into the mounting hole 623 of the second sealing element 62 to fix the support portion 621 of the second sealing element 62, so that the second sealing element 62 is disposed at the second end 402 of the shaft 4.

[0074] In one embodiment, as Figure 14 shown, the harmonic reducer 100 further includes a third base element 72 disposed at the first end 401 of the shaft 4. The structure of the third base element 72 Figure 7 is similar to that of the base element 60 shown. It should be understood that in other embodiments, the third base element 72 can also be removed, as Figure 1 and Figure 2 shown.

[0075] In the above reference Figures 1 to 16In the described embodiment, the first end 401 of the shaft 4 is disposed near the first flange 21, and the cavity 5 is provided between the first flange 21 and the first end 401 of the shaft 4. However, it should be understood that in other embodiments, the first end 401 of the shaft 4 may be disposed within the harmonic reducer 100, near the second flange 22, and the cavity 5 is provided between the second flange 22 and the first end 401 of the shaft 4. In these cases, the sealing mechanism 6 and other arrangements as described above are also applicable. For example, the sealing mechanism 6 referred to above with reference to Figures 3 to 13 The described sealing mechanism 6 may be disposed in the cavity 5, near the second flange 22, and the sealing mechanism 6 referred to above with reference to Figures 14 to 16 The described sealing mechanism 6 may be disposed at the second end 402 of the shaft 4, near the first flange 21. In addition, the pulley 70 may be disposed at the second end 402 of the shaft 4, near the first flange 21.

[0076] According to an embodiment of the present disclosure, the harmonic reducer 100 can be used in various devices or machines, such as industrial robots, power tools, and automobiles. For example, the harmonic reducer 100 can be used to drive the joints of an industrial robot.

[0077] Although multiple inventive embodiments are described and illustrated herein, those of ordinary skill in the art can readily envision various other devices and / or structures for performing the functions described herein and / or obtaining the results and / or one or more advantages described herein, and each such variation and / or modification is considered to fall within the scope of the inventive embodiments described herein. More generally, those skilled in the art will readily understand that all parameters, dimensions, materials, and configurations described herein are exemplary, and the actual parameters, dimensions, materials, and / or configurations depend on one or more specific applications to which the teachings of the present invention are applied. Those skilled in the art will recognize, or be able to ascertain using only routine experimentation, many equivalents of the specific inventive embodiments described herein. Accordingly, it should be understood that the above embodiments are presented by way of example only, and that within the scope of the appended claims and their equivalents, the inventive embodiments may be practiced in other ways than as specifically described and claimed herein. The inventive embodiments of the present disclosure are directed to each separate feature, system, article, material, kit, and / or method described herein. Moreover, any combination of two or more such features, systems, articles, materials, kits, and / or methods (if such features, systems, articles, materials, kits, and / or methods are not mutually inconsistent) is included within the scope of the invention of the present disclosure.

Claims

1. A harmonic speed reducer (100), comprising: a shaft (4) including a first through hole (403), the first through hole (403) extending along the axial direction (X) of the shaft (4) from a first end (401) of the shaft (4) to a second end (402); a wave generator (13), the wave generator (13) being arranged on the shaft (4) and capable of rotating together with the shaft (4); a flexible gear (11) arranged around the wave generator (13); a rigid gear (12) arranged around the flexible gear (11); a first flange (21), the first flange (21) being coupled to the shaft (4) via a first bearing (31) and coupled to the flexible gear (11); and a second flange (22), the second flange (22) being coupled to the shaft (4) via a second bearing (32) and coupled to the rigid gear (12), wherein one of the first flange (21) and the second flange (22) is arranged close to the first end (401) of the shaft (4), and wherein a cavity (5) is provided between one of the first flange (21) and the second flange (22) and the first end (401) of the shaft (4), the cavity (5) being in fluid communication with the external environment via the first through hole (403), and the cavity (5) is also in communication with the internal space of the harmonic speed reducer (100) where the wave generator (13) is located.

2. The harmonic speed reducer (100) according to claim 1, further comprising a porous material (404) arranged in the first through hole (403).

3. The harmonic speed reducer (100) according to claim 1, further comprising a sealing mechanism (6), the sealing mechanism (6) being configured to selectively allow the cavity (5) to be in fluid communication with the external environment via the first through hole (403) according to the internal pressure of the cavity (5).

4. The harmonic speed reducer (100) according to claim 3, wherein, the sealing mechanism (6) includes: a base element (60), the base element (60) being coupled to the first end (401) of the shaft (4) and including a second through hole (603) in fluid communication with the first through hole (403); a first sealing element (61), the first sealing element (61) being arranged on the base element (60) and including one or more openings (613) and a sealing surface (614) around the one or more openings (613), the one or more openings (613) being configured to communicate the cavity (5) with the second through hole (603); and A second sealing element (62) is disposed between the first sealing element (61) and the base element (60), and includes an elastic sealing lip (622) configured to contact the sealing surface (614) of the first sealing element (61) when the internal pressure of the cavity (5) is lower than a pressure threshold to block communication between the cavity (5) and the second through hole (603), and is configured to be pushed away from the sealing surface (614) of the first sealing element (61) when the internal pressure of the cavity (5) is higher than the pressure threshold to enable communication between the cavity (5) and the second through hole (603).

5. The harmonic speed reducer (100) according to claim 4, wherein, the base element (60) includes: a mounting portion (601) inserted into the first through hole (403) at the first end (401) of the shaft (4), and the second through hole (603) is provided on the mounting portion (601); and a receiving portion (602) including a first receiving space (604), a second receiving space (605), and a step (606) between the first receiving space (604) and the second receiving space (605), and the second receiving space (605) is closer to the mounting portion (601) than the first receiving space (604).

6. The harmonic speed reducer (100) according to claim 5, wherein, the first sealing element (61) further includes: a sealing portion (611) disposed in the first receiving space (604) and supported by the step (606), and the one or more openings (613) and the sealing surface (614) are provided on the sealing portion (611); and a mounting post (612) coupled to the sealing portion (611) and configured to mount the second sealing element (62).

7. The harmonic speed reducer (100) according to claim 6, wherein, the second sealing element (62) further includes: a support portion (621) configured to support the elastic sealing lip (622) and including a mounting hole (623) into which the mounting post (612) of the first sealing element (61) is inserted.

8. The harmonic speed reducer (100) according to claim 4, wherein, the base element (60) further includes a groove (607) at its outer surface.

9. The harmonic speed reducer (100) according to claim 3, wherein, the sealing mechanism (6) includes: A second sealing element (62) is arranged at the second end (402) of the shaft (4) and includes an elastic sealing lip (622) configured to contact the second end (402) of the shaft (4) to block communication between the first through hole (403) and the external environment when the internal pressure of the cavity (5) is lower than a pressure threshold, and configured to be pushed away from the second end (402) of the shaft (4) to enable communication between the first through hole (403) and the external environment when the internal pressure of the cavity (5) is higher than the pressure threshold.

10. The harmonic speed reducer (100) according to claim 9, wherein, the second sealing element (62) further includes: a support portion (621) configured to support the elastic sealing lip (622) and including a mounting hole (623).

11. The harmonic speed reducer (100) according to claim 10, further comprising a pulley (70) arranged on the shaft (4) near the second end (402) of the shaft (4) and capable of rotating with the shaft (4), wherein, the sealing mechanism (6) further includes a second base element (63) configured to support the second sealing element (62) and including: a pair of mounting portions (631) coupled to the pulley (70); and a second mounting post (632) inserted into the mounting hole (623) of the second sealing element (62) to fix the support portion (621) of the second sealing element (62).

12. The harmonic speed reducer (100) according to claim 1, further comprising one or more channels (210) arranged between one of the first flange (21) and the second flange (22) and the corresponding one of the first bearing (31) and the second bearing (32).

13. The harmonic speed reducer (100) according to claim 12, further comprising a bearing sleeve (71) arranged around the corresponding one of the first bearing (31) and the second bearing (32).

14. The harmonic speed reducer (100) according to claim 1, further comprising: a crossed roller bearing (14) including an outer ring (141) coupled to the flexible wheel (11) and an inner ring (142) coupled to the rigid wheel (12).

15. An industrial robot comprising the harmonic speed reducer (100) according to any one of claims 1 to 14.

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