Sealing structure

Abstract

The present invention provides a sealing structure for sealing between a housing and a shaft body of a robot drive unit having the housing and the shaft body that rotate relative to each other in accordance with output of a driving force, the shaft body being made of a non-ferrous material lighter than iron, and at least a portion of the shaft body being exposed to the outside of the housing. The sealing structure is provided with: a rotating body sealing member provided in a housing; a contact surface member which is fixed to the shaft main body so as not to move in the longitudinal direction of the shaft main body, rotates integrally with the shaft main body, is in contact with the rotating body sealing member, and has a higher surface hardness than the non-ferrous material; and a sealing member that seals between the shaft body and the contact surface member.

Description

[0001] This application is a divisional application of a Chinese invention patent with an application date of March 25, 2019, a priority date of March 30, 2018, an application number of "201910226743.3", and an invention name of "Drive unit for robot and robot". Technical Field

[0002] The present invention relates to a driving unit for a robot and a robot. Background Art

[0003] Conventionally, there is known a hollow actuator for handling cables inside a robot mechanism, in which the actuator provided between two relatively rotating members is formed hollow (see, for example, Patent Document 1).

[0004] The hollow actuator of Patent Document 1 makes the motor and the reducer coaxial and arranged side by side in the direction along the central axis, adopts a wave gear reducer that is easy to form a hollow structure as the reducer, and uses a hollow shaft that is driven to rotate around the central axis as the shaft that transmits the motor rotation force to the input shaft of the reducer. Through the hollow shaft, the radial inner space can be used as a space for wiring cables, etc., and it is easy to separate from the space of the reducer sealed with lubricating oil arranged on the radial outer side of the hollow shaft. Since the hollow shaft needs to maintain the strength for transmitting power, it is made of high-strength metal such as iron.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 5263162 Summary of the invention

[0008] Problem that the invention aims to solve

[0009] However, in the case of a drive unit having a reduction mechanism that does not require a rotational force input from a shaft driven to rotate around a central axis, such as a gear reduction mechanism, since the hollow shaft is specifically used as a component for radially separating the space for wiring cables, etc. and the space sealed with lubricating oil, when the hollow shaft is made of high-strength metal such as iron, the following undesirable conditions may occur: the weight of the robot increases, and the cost increases due to the shape.

[0010] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a robot drive unit and a robot that can realize a hollow structure to facilitate wiring of cables and the like, thereby achieving lightweight of the robot.

[0011] Solutions for solving problems

[0012] One embodiment of the present invention is a driving unit for a robot, the robot comprising a first component and a second component that rotate relative to each other around a predetermined axis, and the driving unit for the robot comprising: a housing fixed to the first component; an output shaft component supported on the housing in a manner that allows rotation around the axis and fixed to the second component; a cylindrical hollow shaft that is coaxially arranged with the axis and fixed to one of the housing or the output shaft component and supported on the other of the housing or the output shaft component in a manner that allows rotation around the axis; a rotating body sealing component that seals between the housing and the output shaft component and between the other of the housing or the output shaft component and the hollow shaft and allows relative rotation around the axis, respectively, the hollow shaft comprising a shaft body made of a non-ferrous material, and a contact surface component, the contact surface component being fixed to the shaft body and made of a material having a higher surface hardness than the shaft body and constituting a contact surface that contacts the rotating body sealing component.

[0013] According to this scheme, the first component and the second component can be relatively rotated around a predetermined axis by rotating the output shaft component fixed to the second component relative to the housing fixed to the first component. In this case, a cylindrical hollow shaft coaxially arranged with the axis of relative rotation is fixed to one of the first component or the second component, and supported on the other of the first component or the second component in a manner that allows rotation around the axis relative to the housing, thereby allowing the output shaft component to rotate around the axis relative to the housing, and a space is formed inside the hollow shaft that passes through the vicinity of the axis along the axial direction.

[0014] Therefore, by utilizing this space, a filament such as a cable can be laid from the inside of the first member to the inside of the second member that are rotated relative to each other.

[0015] Furthermore, the space surrounded by the housing, the output shaft component and the hollow shaft is sealed by the rotating body sealing components respectively arranged between the housing and the output shaft component and between the housing or the output shaft component and the hollow shaft. That is, a speed reduction mechanism lubricated by a lubricant can be arranged in the enclosed space.

[0016] In this case, the robot can be made lighter by making the shaft body constituting the hollow shaft from a non-ferrous material, that is, a light metal such as resin or aluminum. Furthermore, even if the surface hardness decreases due to the use of non-ferrous materials, the contact surface with the rotating body sealing component can be formed by a contact surface component made of a material having a higher surface hardness than the non-ferrous material, thereby achieving high sealing performance.

[0017] Furthermore, by making the hollow shaft from resin, it is possible to reduce friction with the linear body passing through the hollow hole, thereby maintaining the soundness of the linear body.

[0018] In the above aspect, the robot drive unit may include a bearing that supports the hollow shaft so as to be rotatable relative to the other of the housing and the output shaft member.

[0019] With this structure, the bearing can compensate for the reduction in rigidity of the hollow shaft due to the shaft body being made of a non-ferrous material, thereby preventing a reduction in sealing performance due to a core deviation of the hollow shaft.

[0020] In the above aspect, the bearing may be arranged at a position in contact with at least a portion of the contact surface member along the axial direction.

[0021] With this structure, the bearing that supports the rotation of the hollow shaft directly supports the contact surface member, which can more reliably prevent the contact surface with the sealing member from being tilted, thereby ensuring stable sealing performance.

[0022] In the above aspect, the contact surface member is formed in a cylindrical shape that covers a portion of the outer peripheral surface of the shaft body along the axial direction over the entire circumference.

[0023] With this structure, the contact surface member can be configured to be thinner, thereby achieving weight reduction.

[0024] In the above aspect, the robot drive unit includes a sealing member that seals between the inner peripheral surface of the contact surface member and the outer peripheral surface of the shaft body.

[0025] This structure can prevent the internal lubricant and the like from leaking through between the inner peripheral surface of the contact surface member and the outer peripheral surface of the shaft body.

[0026] In the above aspect, a plurality of the sealing members may be arranged in the axial direction.

[0027] In the above aspect, the contact surface member is formed in a cylindrical shape and is arranged at a position extending from the front end of the shaft body in the axial direction.

[0028] This structure can reduce the weight compared to a case where the entire hollow shaft is made of iron.

[0029] In the above aspect, the inner peripheral surface of the contact surface member is covered with a covering member, and the covering member is made of a polymer compound.

[0030] With this structure, the covering member covering the inner peripheral surface of the contact surface member can reduce friction with the filament body passing through the hollow hole of the hollow shaft, thereby maintaining the soundness of the filament body.

[0031] Another aspect of the present invention is a robot comprising: a first member and a second member that rotate relative to each other around a predetermined axis; and any one of the above-described robot drive units that drives the second member to rotate relative to the first member.

[0032] Effects of the Invention

[0033] According to the present invention, there is an effect that a hollow structure can be realized, the wiring of cables and the like can be facilitated, and the weight of the robot can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a partial longitudinal cross-sectional view showing a robot drive unit and a robot according to an embodiment of the present invention.

[0035] Figure 2 Yes means Figure 1 A partially enlarged longitudinal sectional view of a front end portion of a hollow shaft of a robot drive unit.

[0036] Figure 3 Yes means Figure 1 A perspective view of a front end portion of a hollow shaft of a modified example of a robot drive unit.

[0037] Figure 4 Yes means Figure 1 A cross-sectional view of a hollow shaft of another modified example of a robot drive unit.

[0038] Figure 5 Yes means Figure 1 A partially enlarged longitudinal sectional view of a front end portion of a hollow shaft of a modified example of a robot drive unit.

[0039] Figure 6 Yes means Figure 1 A partial longitudinal sectional view of yet another modified example of a drive unit for a robot.

[0040] Description of Reference Numerals

[0041] 10: Driving unit for robots

[0042] 11: Shell

[0043] 12: Output shaft components

[0044] 13: Hollow shaft

[0045] 14: First sealing member (rotating body sealing member)

[0046] 15: Second sealing member (rotating body sealing member)

[0047] 20, 26: Bearings

[0048] 21: Axis body

[0049] 22: Shaft collar (contact surface component)

[0050] 23: Sealing parts

[0051] 32: Contact surface parts

[0052] 37: Bushing (covering part)

[0053] 110: First Part

[0054] 120: Second part

[0055] A: Axis DETAILED DESCRIPTION

[0056] Hereinafter, a robot driving unit 10 and a robot 100 according to an embodiment of the present invention will be described with reference to the drawings.

[0057] like Figure 1 As shown, the robot 100 of this embodiment comprises: a hollow first component 110; a hollow second component 120, which is supported to be rotatable around a predetermined axis A relative to the first component 110; and a driving unit 10 for the robot of this embodiment, which drives the second component 120 to rotate relative to the first component 110.

[0058] The robot drive unit 10 includes: a housing 11 fixed to a first component 110; an output shaft component 12, which is supported inside the housing 11 in a manner that allows it to rotate around an axis A and is fixed to a second component 120; a hollow shaft 13, which is fixed to the output shaft component 12 and supported on the housing 11 in a manner that allows it to rotate; a first sealing component (rotating body sealing component) 14 that seals between the housing 11 and the output shaft component 12; and a second sealing component (rotating body sealing component) 15 that seals between the housing 11 and the hollow shaft 13.

[0059] The housing 11 includes a cylindrical outer peripheral portion 16 and an end plate 18 having a through hole 17 extending radially inward from one end of the outer peripheral portion 16 in the direction of the axis A and penetrating the center in the direction along the axis A. The output shaft member 12 is formed in a circular annular plate shape, has a through hole 19 penetrating the center in the plate thickness direction, and is rotatably supported by a bearing 20 on the inner peripheral surface of the other end of the outer peripheral portion 16 of the housing 11.

[0060] The hollow shaft 13 includes: a cylindrical shaft body 21 formed of a non-ferrous material such as a resin or a light metal such as aluminum; and a cylindrical collar (contact surface member) 22, which is fitted at a position covering a portion of the outer peripheral surface of one end of the shaft body 21. The collar 22 is made of a material having a higher surface hardness than the shaft body 21, such as iron. The surface hardness of the collar 22 is preferably HRC30 or more.

[0061] The shaft body 21 and the collar 22 are integrated by friction, and a sealing member 23 such as an O-ring is disposed between the shaft body 21 and the collar 22 to seal the fitting surface between the two.

[0062] The shaft body 21 and the collar 22 are precisely managed to achieve a small coaxiality tolerance between the outer surfaces of the shaft body 21 and the collar 22 .

[0063] like Figure 2 As shown, a large diameter portion 38 and a tapered surface 39 are provided at the front end of the shaft body 21. The large diameter portion 38 is slightly larger than the inner diameter of the collar 22, and the tapered surface 39 gradually tapers from the large diameter portion 38 toward the front end of the shaft body 21. Thus, when the collar 22 is fitted with the shaft body 21 from the front end of the shaft body 21, the large diameter portion 38 is reduced in diameter by elastic deformation, and when the fitting is completed, the large diameter portion 38 is expanded in diameter by the elastic restoring force of the shaft body 21, that is, it can be easily assembled in a snap-fit ​​manner.

[0064] The other end of the shaft body 21 has a flange portion 24 extending radially outward. The hollow shaft 13 is fixed in the following manner: when the shaft body 21 is fitted in the through hole 19 of the output shaft member 12, the flange portion 24 is brought into contact with the axial end face of the output shaft member 12 and fixed to the output shaft member 12 by bolts (not shown). The fitting surface between the hollow shaft 13 and the output shaft member 12 is sealed by a sealing member 25 such as an O-ring.

[0065] like Figure 1 and Figure 2 As shown, the second sealing member 15 is arranged between the inner surface of the through hole 17 of the end plate 18 of the housing 11 and one end of the hollow shaft 13. A bearing 26 is arranged at a position adjacent to the second sealing member 15 on the base end side of the hollow shaft 13 along the axis A direction, and the bearing 26 supports the hollow shaft 13 so that it can rotate around the axis A relative to the housing 11. The bearing 26 is arranged at a position where a part of the collar 22 contacts the inner circumferential surface of the inner ring of the bearing 26. That is, the bearing 26 and the collar 22 are arranged in a positional relationship of overlapping in the direction along the axis A.

[0066] Thus, the annular space surrounded by the housing 11, the output shaft member 12 and the hollow shaft 13 is sealed by the first sealing member 14 and the second sealing member 15, and the output shaft member 12 and the hollow shaft 13 are allowed to rotate relative to the housing 11. A reduction mechanism (not shown) is arranged in the sealed space, and the reduction mechanism reduces the speed of the driving force from the motor (not shown) and transmits it to the output shaft member 12. The reduction mechanism is lubricated by a lubricant. The motor is mounted on the outside of the end plate 18, for example, and the motor shaft penetrates the end plate 18 in the plate thickness direction and is inserted into the sealed space.

[0067] The hollow shaft 13 is arranged across the end plate 18 at one end of the housing 11 and the output shaft component 12 at the other end of the housing 11 . The internal space of the hollow shaft 13 penetrates the robot drive unit 10 in the direction along the axis A and is open at both ends of the hollow shaft 13 .

[0068] Thus, the inner space of the hollow shaft 13 is connected to the inner space of the first component 110 and the inner space of the second component 120. Figure 1 As shown, by utilizing the internal space, the filament 130 such as the cable guided into the first component 110 can be routed in the second component 120 through the vicinity of the axis A.

[0069] In the drawings, reference numeral 27 denotes a fixing member for fixing the umbilical body 130 in the first component 110 and the second component 120 respectively.

[0070] Next, the operation of the robot drive unit 10 and the robot 100 according to the present embodiment having such a configuration will be described.

[0071] According to the robot drive unit 10 of the present embodiment, the hollow shaft 13 can form a space for allowing the umbilical body 130 to pass through the vicinity of the axis A which is the rotation center of the output shaft member 12 relative to the housing 11 .

[0072] The linear body 130 passing through the space is mainly twisted due to rotation, and thus will not be subjected to large repeated bending, so it can maintain a healthy state for a long time.

[0073] In this case, according to the present embodiment, compared with the case where the hollow shaft 13 is made of iron, by making the hollow shaft 13 of a non-ferrous material, it is possible to achieve significant weight reduction.

[0074] In particular, in the present embodiment, the hollow shaft 13 is mainly used to separate the reduction mechanism and the annular space enclosed with the lubricant, and does not need to transmit torque, so it does not require a large mechanical strength. Therefore, even if it is made of a low-strength non-ferrous material, there will be no strength problems.

[0075] Since the shaft body 21 is supported by the bearing 26 so as to be rotatable relative to the end plate 18 of the housing 11, even if the shaft body 21 is made of a non-ferrous material having low mechanical strength, it is possible to suppress the core deflection caused by the rotation of the hollow shaft 13. Therefore, the fluctuation of the sealing surface of the second sealing member 15 provided adjacent to the bearing 26 is suppressed, and a stable sealing state can be maintained.

[0076] Moreover, according to the present embodiment, the shaft collar 22 made of a material having a higher surface hardness than the shaft body 21 is arranged on the outer peripheral surface of the front end of the shaft body 21, and the second sealing component 15 is arranged between the outer surface of the shaft collar 22 and the through hole 17. Therefore, compared with the case where the second sealing component 15 is directly brought into contact with the surface of the shaft body 21, it has the following advantages: wear can be prevented and the sealing state between the shaft collar 22 and the second sealing component 15 can be maintained for a long time.

[0077] According to the robot 100 of this embodiment, only by fixing the housing 11 to the first component 110 and fixing the second component 120 to the output shaft component 12, the filament body 130 routed through the inside of the first component 110 can be guided to the inside of the second component 120 through the internal space of the hollow shaft 13. Thus, the filament body 130 can be laid in a manner that is not exposed to the outside.

[0078] Furthermore, even if the second component 120 rotates relative to the first component 110 around the axis A by the robot driving unit 10, a large repeated bending stress will not be applied to the line body 130 laid inside, so that the robot 100 can operate continuously. By forming the shaft body 21 with a soft material such as resin, it is also possible to reduce wear caused by friction between the line body 130 and the shaft body 21, thereby maintaining the integrity of the line body 130.

[0079] There is also an advantage that by reducing the weight of the robot drive unit 10 , it is possible to reduce the weight of the robot 100 itself.

[0080] In this embodiment, the shaft body 21 and the shaft collar 22 are moved integrally by friction, but instead, as Figure 3 As shown, the shaft body 21 may be provided with a recessed portion 28, and the collar 22 may be provided with a convex portion 29 that engages with the recessed portion 28 in the circumferential direction. The engagement of the recessed portion 28 and the convex portion 29 allows the shaft body 21 and the collar 22 to rotate integrally around the axis A.

[0081] In order to achieve the engagement between the recessed portion 28 and the convex portion 29 without a gap, the convex portion 29 of the collar 22 may be engaged with the recessed portion 28 provided on the shaft body 21 while elastically deforming in a direction in which the recessed portion 28 is expanded in the circumferential direction.

[0082] The convex portion 29 may be provided on the shaft body 21, and the concave portion 28 may be provided on the collar 22. In this case, the convex portion 29 provided on the shaft body 21 side may be engaged with the concave portion 28 of the collar 22 while being elastically deformed in the direction of compression in the circumferential direction.

[0083] Two or more convex portions 29 and concave portions 28 may be provided.

[0084] Instead of the engagement between the concave portion 28 and the convex portion 29, as Figure 4 As shown, the key 31 may be inserted into the key groove 30 provided on the mating surface of the shaft body 21 and the collar 22. The key 31 may be a single key or a plurality of keys may be provided at intervals along the circumferential direction. A spline coupling or a sawtooth coupling may be used between the shaft body 21 and the collar 22.

[0085] Although the collar 22 is assembled to the shaft body 21 by snap-fitting, it may be integrally molded by insert molding instead.

[0086] The case where a single O-ring or other sealing member 23 is disposed between the shaft body 21 and the shaft collar 22 is illustrated, but instead, Figure 5 As shown, a plurality of sealing members 23 such as O-rings may be arranged in the longitudinal direction (direction of the axis A) of the shaft body 21. This increases the friction between the shaft body 21 and the collar 22, and improves the anti-rotation effect.

[0087] In this embodiment, as the contact surface member, the collar 22 covering a portion of the outer peripheral surface of the shaft body 21 is exemplified, but instead, Figure 6 As shown in FIG. 1 , the shaft body 21 may be formed of a cylindrical contact surface member 32 connected to the front end of the shaft body 21 and extending from the shaft body 21 in the direction of the axis A. Flanges 34 and 35 are provided at the front end of the shaft body 21 and the base end of the contact surface member 32, respectively, and the flanges 34 and 35 abut in the direction along the axis A and are fitted by bolts 33. The shaft body 21 and the contact surface member 32 are positioned by positioning pins 36. A sealing member needs to be inserted between the joint surfaces of the shaft body 21 and the contact surface member 32 to provide a sealing function.

[0088] In this case, the contact surface member 32 is preferably made of a material having a higher surface hardness than the shaft body 21, such as iron, and the inner peripheral surface of the contact surface member 32 is covered with a bushing (covering member) 37 made of a polymer compound such as tetrafluoroethylene.

[0089] Thus, the shaft body 21 and the contact surface member 32 are integrated, and displacement can be prevented more reliably. The bushing 37 can reduce wear caused by friction with the internal umbilical body 130, and maintain the soundness of the umbilical body 130.

[0090] In this embodiment, the hollow shaft 13 is fixed to the output shaft component 12 and is rotatably sealed between it and the housing 11 by the second sealing component 15. However, alternatively, the hollow shaft 13 may be fixed to the end plate 18 of the housing 11 and is rotatably sealed between it and the output shaft component 12 by the second sealing component 15.

[0091] As the first component 110 and the second component 120, structural components constituting any joint of any type of robot 100 can be adopted. For example, in the case of a vertical multi-joint robot, it can be applied to the joint between the rotating body and the first arm, the joint between the first arm and the second arm, and the like.

Claims

1. A sealing structure, characterized in that: The sealing structure seals between a housing and a shaft body of a robot drive unit having a housing and a shaft body that rotate relative to each other as a driving force is output, wherein the shaft body is made of a non-ferrous material that is lighter than iron, and at least a portion of the shaft body is exposed to the outside of the housing. The sealing structure comprises: A rotating body sealing component, which is arranged on the housing; a contact surface member fixed to the shaft body in a manner that cannot move in the longitudinal direction of the shaft body, rotates integrally with the shaft body, contacts the rotating body seal member, and has a surface hardness higher than that of the non-ferrous material; and A sealing member seals between the shaft body and the contact surface member.

2. The sealing structure according to claim 1, characterized in that: The contact surface member is formed in a cylindrical shape that covers a portion of the outer peripheral surface of the shaft body in the longitudinal direction of the shaft body over the entire circumference.

3. The sealing structure according to claim 2, characterized in that: The sealing member seals between the inner peripheral surface of the contact surface member and the outer peripheral surface of the shaft body.

4. The sealing structure according to claim 3, characterized in that: A plurality of the sealing members are arranged in the longitudinal direction.

5. The sealing structure according to claim 1, characterized in that: The contact surface member is formed in a cylindrical shape and is arranged at a position extending from the front end of the shaft body in the longitudinal direction.

6. The sealing structure according to claim 5, characterized in that: The inner peripheral surface of the contact surface member is covered with a covering member, and the covering member is composed of a polymer compound.

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