WO2022109790A1

WO2022109790A1 - Speed reducer and robot

Info

Publication number: WO2022109790A1
Application number: PCT/CN2020/131176
Authority: WO
Inventors: Xinguo FU
Original assignee: Abb Schweiz Ag
Priority date: 2020-11-24
Filing date: 2020-11-24
Publication date: 2022-06-02
Also published as: CN116324223A

Abstract

According to implementations of the subject matter described herein, there is provided a speed reducer and a robot. The speed reducer comprises: a cavity; an input member rotated by a motor; and a disc operating as an output member of the speed reducer and configured to seal the cavity, the disc comprising: a boss arranged on an inner surface of the disc facing the cavity and extending towards the cavity; and a first hole extending along the length of the boss and through the disc so as to release an air pressure inside the cavity to an ambient environment. The speed reducer can reduce the air pressure in the cavity and thus prevent the leakage of the grease of the cavity. According to implementations of the subject matter described herein, a robot equipped with the speed reducer is provided as well.

Description

[Title established by the ISA under Rule 37.2] SPEED REDUCER AND ROBOT

FIELD

Embodiments of the present disclosure generally relate to a speed reducer and a robot equipped with the speed reducer.

BACKGROUND

A speed reducer is used in a joint of an industrial robot. Typically, the lubricant is retained in a cavity of the speed reducer for lubricating the rotation members of the speed reducer. For an industrial robot, especially for an articulated robot, it is important to prevent a lubricant retained in the speed reducer from leaking out.

An oil seal, as one type of contact seal element, is provided in an output-end member of the speed reducer for preventing leakage of the lubricant. However, when rotation members are running, an air pressure inside the cavity will become higher and higher, which will increase the risk of leakage of the lubricant. Therefore, there is a need for an improved speed reducer and a robot that can be operated reliably.

SUMMARY

According to embodiments of the present disclosure, there is provided an improved speed reducer and a robot that can reduce or eliminate the leakage of the lubricant.

In a first aspect, a speed reducer is provided. The speed reducer comprises: a cavity; an input member rotated by a motor; and a disc operating as an output member of the speed reducer and configured to seal the cavity, the disc comprising: a boss arranged on an inner surface of the disc facing the cavity and extending towards the cavity; and a first hole extending along the length of the boss and through the disc so as to release an air pressure inside the cavity to an ambient environment.

With the first hole, the air pressure inside the cavity may release to an ambient environment. The reduced air pressure inside the cavity is beneficial for reducing or eliminating the leakage of the lubricant caused by high air pressure. With the boss protruding from the disc, it is difficult for the lubricant to adhere on a tip end of the boss. In this way, the lubricant will not leak from the first hole.

In some embodiments, the disc further comprises a second hole in fluid communication with the first hole. This is beneficial because it makes the manufacture of the first hole and the second hole easier.

In some embodiments, the second hole is formed as a screw hole for receiving a set screw. The set screw may prevent dust or other contaminants from invading into the speed reducer though the first hole.

In some embodiments, the second hole extends from an outer surface of the disc towards the cavity, and has a base surface at a certain distance from the inner surface of the disc; wherein the outer surface is opposite to the inner surface. With this arrangement, the second hole may be manufactured easily.

In some embodiments, the speed reducer further comprises a transmission assembly coupled between the input member and the disc; and wherein the transmission assembly is configured to reduce a speed of rotation from the motor and to transmit the speed-reduced rotation to the disc.

In some embodiments, the transmission assembly comprises: a circular rigid gear having inner teeth formed on an inner peripheral surface; and an annular flexible gear positioned at the inside of the rigid gear, and having outer teeth formed on a portion of an outer peripheral surface which are engageable with the inner teeth; and a wave generator attached to the input member and configured to deflect the flexible gear in radial directions; wherein the disc is attached to the flexible gear to output a rotation movement. The improved speed reducer formed as a harmonic reducer may reduce or eliminate the leakage of the lubricant caused by high air pressure in the cavity.

In some embodiments, the transmission assembly comprises: a first stage reduction gear mechanism comprising: a first input gear attached to the input member; and three second spur gears individually meshing with the first input gear; a second stage reduction gear mechanism comprising: an internal gear member; two external gear members meshing with the internal gear member; three crankshafts engaging with the two external gear members for eccentrically rocking the two external gear members with respect to the internal gear member; and a support member for rotatably supporting the crankshaft, so that an output is extracted from the internal gear member or the support member; in the case that the output is extracted from the internal gear member, the disc is coupled to the internal gear member, and wherein in the case that the output is extracted from the support member, the disc is coupled to the support member. The improved speed reducer formed as a rotary vector (RV) reducer may reduce or eliminate the leakage of the lubricant caused by high air pressure in the cavity.

In some embodiments, the motor is attached to the disc. This arrangement may simplify the structure of the speed reducer.

In some embodiments, the cavity is provided with grease for lubricating. The grease is difficult to adhere on the tip end of the boss, and thereby the leakage through the first hole may be reduced.

In a second aspect, a robot is provided. The robot comprises: a first arm; a second arm, and the speed reducer according to the first aspect of the present disclosure coupled between the first arm and the second arm.

The Summary introduces a selection of concepts in a simplified form that are further described below in the Detailed Description. The Summary is not intended to identify key features or essential features of the subject matter described herein, nor is it intended to be used to limit the scope of the subject matter described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Through the more detailed description of some embodiments of the present disclosure in the accompanying drawings, the above and other objects, features and advantages of the present disclosure will become more apparent, wherein:

Fig. 1 illustrates an example robot according to embodiments of the present disclosure;

Fig. 2 illustrates a perspective view of an example speed reducer according to embodiments of the present disclosure;

Fig. 3 illustrates a cross-sectionanl view of the example speed reducer of Fig. 2 in which an enlarged view of a portion of the example speed reducer is shown as well; and

Fig. 4 illustrates another example speed reducer according to embodiments of the present disclosure.

Throughout the drawings, the same or similar reference symbols refer to the same or similar elements.

DETAILED DESCRIPTION OF IMPLEMENTATIONS

Principles of the subject matter described herein will now be described with reference to some example implementations. It should be understood that these implementations are described only for the purpose of illustration and to help those skilled in the art to better understand and thus implement the subject matter described herein, without suggesting any limitations to the scope of the subject matter disclosed herein.

As used herein, the term “based on” is to be read as “based at least in part on. ” The terms “an implementation” and “one implementation” are to be read as “at least one implementation. ” The term “another implementation” is to be read as “at least one other implementation. ” The term “first, ” “second, ” and the like may refer to different or the same objects. Other definitions, either explicit or implicit, may be included below.

It should be further understood that the terms “comprises” , “comprising” , “has” , “having” , “includes” and/or “including” , when used herein, specify the presence of stated features, elements, and/or components, etc., but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof.

Speed reducers are common components in joints of a robot and lubricant is often filled in the speed reducers for lubricating the rotatory members. In order to reduce or eliminate the leakage of the lubricant, an improved speed reducer and a robot are provided.

Fig. 1 illustrates an example robot according to embodiments of the present disclosure, i.e., an articulated robot. The robot comprises articulated

portions

1, 2, 3, 4, 5, to which speed reducers are individually attached. A first arm 31, a second arm 32, a third arm 33, a fourth arm 34 and a fifth arm 35 may rotate around the articulated

portions

1, 2, 3, 4, 5, respectively.

With reference to Fig. 1, for example, the speed reducer 10 according to embodiments of the present disclosure may be coupled between the first arm 31 and the second arm 32, and/or between the second arm 32 and the third arm 33, and/or between the third arm 33 and the fourth arm 34, and/or between the fourth arm 34 and the fifth arm 35. With the speed reducer 10, the relative movement of two jointed arms of the robot can be achieved in a desirable manner.

It should be understand that the speed reducer 10 according to embodiments of the present disclosure may be applied to a different robot, such as, a parallel robot or a robot having more or fewer arms than the robot of Fig. 1.

Speed reducers are used to reduce a speed of rotation from a motor and transmit the speed-reduced rotation to an arm. Figs. 2-3 illustrate an example speed reducer according to embodiments of the present disclosure, and Fig. 4 illustrates another example speed reducer according to embodiments of the present disclosure. In general, the speed reducer 10 comprises a cavity 11, an input member 13 and a disc 15. The input member 13 is configured to be rotated by a motor 19 and the disc 15 is operated as an output member of the speed reducer 10.

The disc 15 is configured to seal the cavity 11. In some embodiments, the disc 15 may be formed as a flange. In some embodiments, the cavity 11 is provided with grease for lubricating the rotation members of the speed reducer 10. For example, the grease is used for lubricating bearings 16 inside the speed reducer 10. With the disc 15 sealing the cavity 11, the grease may be retained in the cavity 11 without leaking to the ambient environment.

As shown in Figs. 2-4, the disc 15 comprises a boss 151 and a first hole 153. The boss 151 is arranged on an inner surface 152 of the disc 15 facing the cavity 11 and the boss 151 extends towards the cavity 11. With the boss 151 extending towards the cavity 11, the tip end 1511 of the boss 151 is disposed away from the inner surface 152. As such, due to the boss 151 protruding from the inner surface 152, it is difficult for the lubricant to adhere on the tip end 1511 of the boss 151. In some embodiments, the boss 151 may be a cylindrical protrusion.

As the disc 15 is operated as an output member of the speed reducer 10, the disc 15 is a rotatory member for outputting a rotation movement. In this case, even if the lubricant was to adhere on the tip end 1511 of the boss 151, the lubricant would certainly fall from the tip end 1511 of the boss 151 under centrifugal force.

The first hole 153 extends along the length of the boss 151 and through the disc 15 such that the cavity 11 is in fluid communication with the ambient environment. In this way, the first hole 153 may release an air pressure inside the cavity 11 to the ambient environment. Thus, the high pressure caused by the running of the rotation members may be released through the first hole 153. The reduced air pressure inside the cavity 11 is beneficial to reduce or eliminate the leakage of the lubricant in the cavity 11.

In some embodiments, a diameter of the first hole 153 is required to be as small as possible. In this case, the disc 15 may further comprise a second hole 155 which is in fluid communication with the first hole 153. Since the requirement for a diameter of the second hole 155 is not as rigorous as that of the first hole 153, both the first hole 153 and the second hole 155 can be manufactured easily.

In some embodiments, the second hole 155 may be formed as a screw hole for receiving a set screw 156. The set screw 156 may prevent dust or other contaminants from entering into the speed reducer 10 though the first hole 153. In the meantime, when the air pressure in the cavity 11 increases, the air in the cavity 11 may escape to the ambient environment through the first hole 153 and the gap between the screw hole and the set screw 156. As such, the set screw 156 does not block the release of the air in the cavity 11.

In some embodiments, the second hole 155 may extend from an outer surface 154 of the disc 15, which is opposite to the inner surface 152, towards the cavity 11. The second hole 155 may have a base surface 1551 at a certain distance from the inner surface 152 of the disc 15. As shown in Figs. 2-4, the first hole 153 extends along the length of the boss 151 and through the disc 15, and then is in fluid communication with the second hole 155.

In some embodiments, the speed reducer 10 may further comprise a transmission assembly 14. The transmission assembly 14 is coupled between the input member 13 and the disc 15 for reducing a speed of rotation from the motor 19 and then transmitting the speed-reduced rotation to the disc 15.

In some embodiments, the speed reducer 10 is formed as a harmonic reducer. As shown in Figs. 2-3, the transmission assembly 14 may comprise a circular rigid gear 140, an annular flexible gear 141 and a wave generator 142. The rigid gear 140 has inner teeth formed on an inner peripheral surface, and the flexible gear 141 has outer teeth formed on a portion of its outer peripheral surface 1411. The outer teeth of the flexible gear 141 can be engaged with the inner teeth of the rigid gear 140.

The flexible gear 141 is positioned within the rigid gear 140 while surrounding the wave generator 142. The wave generator 142 has an outer peripheral surface that is formed to an elliptical shape. The flexible gear 141 is capable of deflecting in radial directions. The number of teeth of the flexible gear 141 is set to be slightly less than the number of teeth of the rigid gear 140.

At its major axis portions, the wave generator 142 deflects the flexible gear 141 in radial directions and causes the outer teeth of the flexible gear 141 to engage with the inner teeth of the rigid gear 140.

The wave generator 142 is attached to the input member 13. In this manner, when the wave generator 142 is rotated by the input member 13, the engagement points, at which the outer teeth of the flexible gear 141 and the inner teeth of rigid gear 140 engage, move in a circumferential direction in accordance with the variation of the positions of the major axis portions of the wave generator 142. That is, the wave generator 142 and the flexible gear 141 are respectively used as an input and an output.

As shown in Figs. 2-3, the disc 15 is attached to the flexible gear 141 to output a rotation movement. In this way, the disc 15 is operated as an output member of the speed reducer 10. Also, the cavity 11 of the speed reducer 10 may comprise a space formed by the wave generator 142, the flexible gear 141, the disc 15 and the bearing 16.

In some embodiments, the speed reducer 10 may be formed as a rotary vector (RV) reducer, as shown in Fig. 4. The transmission assembly 14 is constituted to comprise a first stage reduction gear mechanism 145 and a second stage reduction gear mechanism 146 for reducing the speed of rotation from the motor 19.

The first-stage reduction gear mechanism 145 comprises a first input gear and three second spur gears. In some embodiments, the first input gear may be attached to the input member 13 or may be formed integrally with the input member 13. The three second spur gears are individually meshed with the first input gear and equally arranged around the first input gear.

The second-stage reduction gear mechanism 146 is formed as an eccentrically rocking type speed reducer and comprises: an internal gear member having internal teeth of a plurality of pins as internal teeth; two external gear members having external teeth meshing with the internal teeth of the internal gear member; three crankshafts engaging with the two external gear members for rocking the two external gear members with respect to the internal gear member; a support member for supporting the three crankshafts rotatably, so that an output is extracted from the internal gear member or the support member. Each of the three crankshafts is coupled to one of the three second spur gears.

As discussed above, the disc 15 is operated as an output member of the speed reducer 10. Thus, in the case that the output is extracted from the internal gear member, the disc 15 is coupled to the internal gear member. Alternatively, in the case that the output is extracted from the support member, the disc 15 is coupled to the support member. In some embodiments, as shown in Fig. 4, the motor 19 may be attached to the disc 15. This arrangement may simplify the overall structure of the speed reducer 10 and the motor 19.

The cavity 11 of the speed reducer 10 may comprise a space between the disc 15 and the supporting member. Alternatively, the cavity 11 of the speed reducer 10 may comprise a space between the disc 15 and the first stage reduction gear mechanism 145, as shown in Fig. 4. Due to the boss 151 protruding from the inner surface 152, it is difficult for the lubricant (such as grease) within the cavity 11 to adhere on the tip end 1511 of the boss 151. With the first hole 153, the high pressure of the cavity 11 may be released, whereby the leakage of the grease can be reduced or eliminated.

It should be appreciated that the above detailed embodiments of the present disclosure are only to exemplify or explain principles of the present disclosure and not to limit the present disclosure. Therefore, any modifications, equivalent alternatives and improvements, etc. without departing from the spirit and scope of the present disclosure shall be comprised in the scope of protection of the present disclosure. Meanwhile, appended claims of the present disclosure aim to cover all the variations and modifications falling under the scope and boundary of the claims or equivalents of the scope and boundary.

Claims

A speed reducer (10) , comprising:

a cavity (11) ;

an input member (13) rotated by a motor (19) ; and

a disc (15) operating as an output member of the speed reducer (10) and configured to seal the cavity (11) , the disc (15) comprising:

a boss (151) arranged on an inner surface (152) of the disc (15) facing the cavity (11) and extending towards the cavity (11) ; and

a first hole (153) extending along the length of the boss (151) and through the disc (15) so as to release an air pressure inside the cavity (11) to an ambient environment.
The speed reducer (10) according to claim 1, wherein the disc (15) further comprises a second hole (155) in fluid communication with the first hole (153) .
The speed reducer (10) according to claim 2, wherein the second hole (155) is formed as a screw hole for receiving a set screw (156) .
The speed reducer (10) according to claim 3, wherein the second hole (155) extends from an outer surface (154) of the disc (15) towards the cavity (11) , and has a base surface (1551) at a certain distance from the inner surface (152) of the disc (15) ; wherein the outer surface (154) is opposite to the inner surface (152) .
The speed reducer (10) according to claim 1, further comprises a transmission assembly (14) coupled between the input member (13) and the disc (15) ; and

wherein the transmission assembly (14) is configured to reduce a speed of rotation from the motor (19) and to transmit the speed-reduced rotation to the disc (15) .
The speed reducer (10) according to claim 5, wherein the transmission assembly (14) comprises:

a circular rigid gear (140) having inner teeth formed on an inner peripheral surface;

an annular flexible gear (141) positioned at the inside of the rigid gear (140) , and having outer teeth formed on a portion of an outer peripheral surface (1411) which are engageable with the inner teeth; and

a wave generator (142) attached to the input member (13) and configured to deflect the flexible gear (141) in radial directions;

wherein the disc (15) is attached to the flexible gear (141) to output a rotation movement.
The speed reducer (10) according to claim 5, wherein the transmission assembly (14) comprises:

a first stage reduction gear mechanism (145) comprising:

a first input gear attached to the input member (13) ; and

three second spur gears individually meshing with the first input gear;

a second stage reduction gear mechanism (146) comprising:

an internal gear member;

two external gear members meshing with the internal gear member;

three crankshafts engaging with the two external gear members for eccentrically rocking the two external gear members with respect to the internal gear member; and

a support member for rotatably supporting the crankshaft, so that an output is extracted from the internal gear member or the support member;

in the case that the output is extracted from the internal gear member, the disc (15) is coupled to the internal gear member; and

wherein in the case that the output is extracted from the support member, the disc (15) is coupled to the support member.
The speed reducer (10) according to claim 7, wherein the motor (19) is attached to the disc (15) .
The speed reducer (10) according to any one of claims 1-8, wherein the cavity (11) is provided with grease for lubricating.
A robot, comprising:

a first arm;

a second arm;

the speed reducer (10) according to any one of claims 1-9 coupled between the first arm and the second arm.