Robot joint structure

Abstract

The robot's joint structure includes: a hollow first component and a hollow second component; and an actuator, the actuator including: a motor, which is fixed in the first component in a housed state; a reducer, which reduces the rotation of the motor and transmits it to the second component; and a power transmission mechanism, which transmits the power of the motor to the reducer, the reducer including: a hollow hole extending along a first axis; and an input component, which is supported to rotate about the first axis and receives power transmitted by the power transmission mechanism, the power transmission mechanism including: a first power transmission part having an output component supported in a manner rotatable about a second axis, transmitting power to the input component; a second power transmission part, which transmits power between an axis supported in a manner rotatable about a third axis and the output component; and a housing housing the second power transmission part and supporting the motor, the housing being detachably mounted on the first component at a position offset radially outward relative to the hollow hole.

Description

Technical Field

[0001] This invention relates to the joint structure of robots. Background Technology

[0002] A known robot joint structure comprises two arms supported by a reducer in a manner capable of relative rotation about a rotation axis. A motor is housed within the arms by using bevel gears as gears to transmit motor driving force to the reducer (see, for example, Patent Document 1). This joint structure uses bevel gears to configure the motor axis in a direction orthogonal to the rotation axis of the arms.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2007-144559 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] When using bevel gears, the meshing of the bevel gears needs to be adjusted. However, it is difficult to adjust the meshing of the bevel gears mounted on the motor and the bevel gears mounted on the reducer while simultaneously installing the motor into the arm. Therefore, it is desirable to have easy adjustment and easy motor installation within the arm.

[0008] Solution for solving the problem

[0009] One aspect of the present invention is a joint structure for a robot, characterized by comprising: a hollow first component; a hollow second component; and an actuator that causes the first component and the second component to rotate relative to each other about a first axis. The actuator includes: a motor fixed within the first component in a receptacle state; a reducer that reduces the rotation of the motor's shaft and transmits it to the second component; and a power transmission mechanism that transmits power from the motor to the reducer, the reducer having: a hollow hole extending along the first axis; and an input component supported to rotate about the first axis and receiving power transmitted by the power transmission mechanism.

[0010] The power transmission mechanism comprises: a first power transmission unit having an output component supported in a manner rotatable about a second axis parallel to the first axis, and transmitting power to the input component; a second power transmission unit transmitting power between the output component and a shaft supported in a manner rotatable about a third axis, the third axis being disposed in a plane intersecting the second axis; and a housing housing the second power transmission unit and supporting the motor.

[0011] The housing is mounted on the first component in a detachable manner at a position offset radially outward relative to the hollow hole. Attached Figure Description

[0012] Figure 1 This is a schematic diagram illustrating an example of a robot having a joint structure according to an embodiment of the present invention.

[0013] Figure 2 It means Figure 1 An enlarged longitudinal sectional view of the joint structure.

[0014] Figure 3 It means Figure 1 The exploded longitudinal sectional view of the joint structure's constituent units.

[0015] Figure 4 yes Figure 1 An exploded longitudinal sectional view of the joint structure.

[0016] Figure 5 It means from Figure 1 A longitudinal sectional view of the joint structure in the state of disassembling the second cover component of the first arm.

[0017] Explanation of reference numerals in the attached figures:

[0018] 1: Joint structure

[0019] 20: Motor (Actuator)

[0020] 30: Reducer (Actuator)

[0021] 31: Input gear (input component)

[0022] 32: Hollow hole

[0023] 40: Power transmission mechanism (gearbox, actuator)

[0024] 41: Outer shell

[0025] 42: First gear (output component, first power transmission unit)

[0026] 43: Second gear (second power transmission unit)

[0027] 44: Third gear (second power transmission unit)

[0028] 45: First opening

[0029] 46; First cover component

[0030] 70: Bearing

[0031] 100: Robot

[0032] 130: First arm (first component)

[0033] 131: Second opening

[0034] 132: Second cover component

[0035] 140: Second arm (second component)

[0036] C: First axis

[0037] D: Second axis

[0038] E: Third axis Detailed Implementation

[0039] The joint structure 1 of a robot according to one embodiment of the present invention will now be described with reference to the accompanying drawings.

[0040] The robot 100 equipped with the joint structure 1 of this embodiment, for example Figure 1 As shown, it is a vertical six-axis articulated robot, and has a base 110 mounted on the ground F, and a rotating body 120 supported in a manner that allows it to rotate relative to the base 110 about a vertical axis A.

[0041] Furthermore, the robot 100 includes: a first arm (first component) 130, which is supported in a manner rotatable relative to the rotating body 120 about a horizontal axis B; and a second arm (second component) 140, which is supported in a manner rotatable relative to the first arm 130 about a horizontal first axis C. The robot 100 also includes a three-axis wrist unit 150 in the second arm 140.

[0042] like Figure 2 As shown, the joint structure 1 in this embodiment is, for example, a structure between a first arm 130 and a second arm 140, and includes a first arm 130, a second arm 140, and an actuator that drives the second arm 140 to rotate relative to the first arm 130 about a first axis C.

[0043] The first arm 130 and the second arm 140 are each configured as a hollow cylinder with a long axis.

[0044] The actuator includes a motor 20, a reducer 30, and a gearbox (power transmission mechanism) 40 that transmits power from the motor 20 to the reducer 30.

[0045] The motor 20 is detachably fixed to the housing 41 that constitutes the gearbox 40, as described later. The gearbox 40 is detachably fixed to the first arm 130. Thus, the motor 20 is indirectly fixed to the first arm 130 via the gearbox 40.

[0046] The reducer 30 includes: a housing fixed to a first arm 130; and an output shaft supported in a manner rotatable relative to the housing about a first axis C and fixed to a second arm 140. The reducer 30 has a hollow hole 32 extending through the first axis C in its center, in a region including the first axis C.

[0047] In the hollow hole 32, a line body (not shown) is arranged in a through-hole manner.

[0048] Furthermore, the reducer 30 has an input gear (input component) 31 on the side of the first arm 130. The input gear 31 is supported in a rotatable manner about the first axis C and is composed of a spur gear or a helical gear. The rotation of the shaft of the motor 20 is input to the input gear 31, which rotates about the first axis C, thereby reducing the speed of the rotation within the reducer 30 and outputting it as the rotation of the output shaft, driving the second arm 140 to rotate.

[0049] The gearbox 40 includes: a first gear (output component, first power transmission part) 42 that meshes with the input gear 31; a second gear (second power transmission part) 43 fixed to the first gear 42; a third gear (second power transmission part) 44 fixed to the shaft of the motor 20 and meshing with the second gear 43; and a housing 41.

[0050] Additionally, the housing 41 houses a second gear 43 and a third gear 44. The first gear 42 is composed of a spur gear or a helical gear that meshes with the input gear 31. Thus, the second axis D of the first gear 42 is arranged parallel to the first axis C of the input gear 31.

[0051] The first gear 42 and the second gear 43 are supported within the housing 41 by bearings 70 in a manner that allows them to rotate about a predetermined axis. The bearings 70 are mounted in the housing 41 with appropriate preload to support both radial and axial forces acting on the first gear 42 and the second gear 43.

[0052] The second gear 43 and the third gear 44 are both bevel gears. The third gear 44 is mounted on the shaft of the motor 20. By meshing the third gear 44 with the second gear 43 within the housing 41, the third axis E of the shaft of the motor 20 and the second axis D of the first gear 42 and the second gear 43 are arranged in an orthogonal position.

[0053] like Figure 3As shown, the housing 41 has a first opening 45, which exposes the meshing position of the second gear 43 and the third gear 44 to the outside. The first opening 45 is closed by a first cover member 46. When assembling the gearbox 40, the third gear 44, which is rotatably supported by the first gear 42 and the second gear 43 by the bearing 70, is inserted into the housing 41, which is mounted on the shaft of the motor 20, so that the second gear 43 and the third gear 44 mesh.

[0054] At this time, the thickness of the shim sandwiched between the motor 20 and the housing 41 is changed, and the meshing of the second gear 43 and the third gear 44 is adjusted. With the second gear 43 and the third gear 44 properly meshed and the motor 20 installed, an appropriate amount of lubricating material is supplied into the housing 41, and the first opening 45 is closed using the first cover member 46. Thus, a unit 50 for fixing the motor 20 to the gearbox 40 is formed.

[0055] The first arm 130 is provided with a second opening 131 through which the unit 50 can pass, and a second cover member 132 is provided to close the second opening 131 in an openable and closable manner. The unit 50 is installed as follows: at a position radially offset relative to the hollow hole inside the first arm 130, parallel to the second axis D of the first gear 42, and with the long axis of the motor 20 parallel to the long axis of the first arm 130.

[0056] like Figure 4 As shown, the first arm 130 has a recess parallel to the first axis C, and the outer casing 41 has a recess that fits into the recess. By fitting the recess into the recess, the unit 50 is mounted on the first arm 130, so that the first gear 42 of the gearbox 40 meshes appropriately with the input gear 31 of the reducer 30.

[0057] In the figure, reference numeral 60 indicates an actuator that drives the wrist unit 150 to rotate relative to the second arm 140.

[0058] The function of the joint structure 1 of the robot in this embodiment, configured as described below, will be explained.

[0059] When the joint structure 1 of the robot 100 of this embodiment is assembled... Figure 3 As shown, firstly, the first cover component 46 is removed from the housing 41 to open the first opening 45. Then, outside the first arm 130, inside the housing 41, the first gear 42 and the second gear 43 are rotatably supported by bearings 70. Afterward, the motor 20, with the third gear 44 mounted on its shaft, is installed in the housing 41.

[0060] When the motor 20 is mounted on the housing 41, the third gear 44, which is composed of bevel gears, mounted on the shaft of the motor 20, meshes with the second gear 43, which is composed of bevel gears, housed inside the housing 41. At this time, the meshing position of the third gear 44 and the second gear 43 is exposed to the outside through the first opening 45, so the meshing can be adjusted appropriately and easily.

[0061] In this way, the unit 50, which is equipped with the gearbox 40 and motor 20 after meshing adjustment, can be easily assembled outside the first arm 130.

[0062] Then, as Figure 5 As shown, the assembled unit 50 is inserted into the first arm 130 via the second opening 131, which is opened by disassembling the second cover member 132 of the first arm 130, and is installed in the first arm 130 at a position offset from the hollow hole 32 of the reducer 30. At this time, the recess of the housing 41 of the gearbox 40 constituting the unit 50 fits into the recess of the first arm 130.

[0063] Then, when the recesses engage with each other, the first gear 42 and the input gear 31 of the reducer 30 are meshed.

[0064] Since the first gear 42 and the input gear 31 are both spur gears, the first gear 42 and the input gear 31 can be properly meshed by moving the gearbox 40 in a direction parallel to the first axis C while the recesses are engaged. Then, the second opening 131 of the first arm 130 is closed with the second cover 132 to complete the assembly.

[0065] Thus, according to the joint structure 1 of the robot in this embodiment, by utilizing bevel gears to bend the power transmission path from the motor 20 to the reducer 30 at a right angle, the motor 20 can be positioned along the long axis of the first arm 130. As a result, it has the advantage that the amount of protrusion of the motor 20 from the reducer 30 in the direction of the first axis C is minimized, thereby minimizing the size of the first arm 130 that houses the motor 20.

[0066] Furthermore, by arranging the motor 20 along the first arm 130, the proportion of the motor 20 in the cross-section inside the first arm 130 can be reduced. This provides the advantage of ensuring sufficient space for arranging the linear elements and other components.

[0067] In addition, the third gear 44, which is made of bevel gears and is installed in the motor 20, and the second gear 43, which is made of bevel gears and is installed in the housing 41, mesh outside the first arm 130, rather than inside the narrow first arm 130, so that the assembly operation is easy to perform.

[0068] Furthermore, inside the first arm 130, the first gear 42 and the input gear 31 can be properly meshed simply by engaging the recess of the housing 41 with the recess of the first arm 130. Therefore, no meshing adjustment of the first gear 42 and the input gear 31 is required, and assembly can be performed easily.

[0069] In this embodiment, the second gear 43 and the third gear 44, which are composed of bevel gears, bear the axial load by rotating, and the axial load generated by the second gear 43 is supported by the bearing 70. The axial load generated by the third gear 44 is supported by a bearing located inside the motor 20.

[0070] Alternatively, the third gear 44 can also be supported inside the housing 41 by bearings, thereby supporting loads in both the radial and axial directions. In this case, the connection between the third gear 44 and the shaft of the motor 20 can be achieved using a spline connection or a key connection, etc.

[0071] In addition, in this embodiment, the joint structure 1 between the first arm 130 and the second arm 140 is illustrated as an example, but alternatively, it can also be applied to the joint structure between the rotating body 120 and the first arm 130 or the joint structure in the wrist unit 150.

[0072] Furthermore, an example is given of a case where a spur gear or helical gear serves as an input component, and an output component composed of a spur gear or helical gear serves as the first power transmission unit. Alternatively, the output component and the input component can be composed of pulleys, with these pulleys and a belt mounted on the pulleys serving as the first power transmission unit.

[0073] In addition, the second gear 43 and the third gear 44 are made of bevel gears, but as an alternative, gears capable of transmitting power between intersecting axes, such as hypoid gears, can also be used.

Claims

1. A joint structure for a robot, characterized in that, have: The first hollow component; The hollow second component; and An actuator that causes the first component and the second component to rotate relative to each other about a first axis. The actuator includes: a motor, which is fixed in a housed state within the first component; a reducer, which reduces the rotation of the motor shaft and transmits it to the second component; and a power transmission mechanism, which transmits the power of the motor to the reducer. The reducer includes: a hollow hole extending along the first axis; and an input component supported for rotation about the first axis and receiving power transmitted by the power transmission mechanism. The input component is composed of spur gears or helical gears. The power transmission mechanism comprises: a first power transmission unit having an output component supported in a manner rotatable about a second axis parallel to the first axis, and transmitting power to the input component; a second power transmission unit transmitting power between the output component and a shaft supported in a manner rotatable about a third axis, the third axis being disposed in a plane intersecting the second axis; and a housing housing the second power transmission unit and supporting the motor. The first component has a recess that is parallel to the first axis. The housing has a recessed portion configured to fit into the recessed portion, and is mounted on the first component in a detachable manner at a position offset radially outward relative to the hollow hole by fitting into the recessed portion.

2. The joint structure of the robot according to claim 1, characterized in that, The first power transmission unit is a first gear that meshes with the input component. The second power transmission unit includes: a second gear fixed to the first gear and composed of a bevel gear; and a third gear meshing with the second gear and connected to the motor, and also composed of a bevel gear.

3. The joint structure of the robot according to claim 2, characterized in that, The housing includes: a first opening that exposes the meshing position of the second gear and the third gear; and a first cover member that can be opened and closed to close the first opening.

4. The joint structure of the robot according to claim 2, characterized in that, The housing includes bearings that rotatably support the first gear and the second gear, and support forces in the radial and axial directions.

5. The joint structure of the robot according to any one of claims 1 to 4, characterized in that, The first component includes: a second opening through which the housing in which the motor is mounted passes; and a second cover component that can be opened and closed to close the second opening.

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