robot

Abstract

The present invention provides a robot capable of reducing the moment of inertia during the rotation of the second arm. [Solution] A robot comprising: a second arm; a shaft provided at the tip of the second arm, rotatable around a third axis and movable up and down along the third axis; a first motor that generates power to rotate the shaft; a second motor that generates power to move the shaft up and down; and a first transmission unit, wherein the first transmission unit has a first pulley, a second pulley, a first endless belt wrapped around the first and second pulleys, a third pulley, a fourth pulley, and a second endless belt wrapped around the third and fourth pulleys, and the second and third pulleys are located below the second motor in a first direction parallel to the third axis.

Description

Technical Field

[0001] The present invention relates to a robot.

Background Art

[0002] The robot described in Patent Document 1 includes a base, a first arm provided on the base and rotatable relative to the base, a second arm provided on the first arm and rotatable relative to the first arm, and a shaft provided on the second arm that is rotatable and capable of moving up and down. The second arm is provided with a motor that generates power for rotating the shaft, and a belt and a spline mechanism that transmit the power of this motor to the shaft. Further, the second arm is provided with a motor that generates power for moving the shaft up and down, and a belt and a lead screw mechanism that transmit the power of this motor to the shaft. An end effector is attached to the tip of the shaft. It is known that in order to rotate the shaft and the end effector, a certain amount of torque needs to be applied to the shaft, and a transmission unit that decelerates the rotation of the motor for shaft rotation and transmits it to the shaft is provided in the second arm.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of Invention

Problem to be Solved by the Invention

[0004] However, depending on the position and mass of the transmission unit, the moment of inertia when rotating the second arm may increase.

Means for Solving the Problem

[0005] A robot according to an application example of the present invention is a base, and A first arm is provided on the base and is rotatable about a first axis relative to the base, A second arm is provided on the first arm and is rotatable around a second axis parallel to the first axis relative to the first arm, A shaft provided at the tip of the second arm, which is rotatable around a third axis parallel to the second axis and can move up and down along the third axis, A first motor is provided on the second arm and generates power to rotate the shaft, A second motor is provided on the second arm and generates power to raise and lower the shaft, A first transmission unit is provided on the second arm and reduces the rotation of the first motor and transmits it to the shaft, A second transmission unit is provided on the second arm and transmits the rotation of the second motor to the shaft, Equipped with, When the direction parallel to the third axis is defined as the first direction, The first transmission unit is, A first pulley is located on the lower side of the first motor in the first direction and is fixed to the output shaft of the first motor, A second pulley is located between the first pulley and the shaft, A first endless belt is wrapped around the first pulley and the second pulley, A third pulley is fixed coaxially to the second pulley, A fourth pulley is provided coaxially with the aforementioned shaft, The second endless belt is wrapped around the third pulley and the fourth pulley, It has, The second pulley and the third pulley are located on the lower side of the second motor in the first direction. [Brief explanation of the drawing]

[0006] [Figure 1] This is a side view showing a robot system comprising a robot according to an embodiment of the present invention. [Figure 2]This is a partial cross-sectional view of the second arm of the robot shown in Figure 1. [Figure 3] This is an enlarged view of the area enclosed by the dashed line III in Figure 2. [Figure 4] Figure 2 is a perspective view showing the support member fixed to the arm base of the second arm. [Modes for carrying out the invention]

[0007] Embodiments of the present invention will be described below with reference to the drawings. The following description is not intended to limit the technical scope or meaning of terms as defined in the claims. Furthermore, the dimensional ratios in the drawings are exaggerated for illustrative purposes and may differ from actual ratios. In embodiments of the present invention, unless otherwise specified and limited, terms such as "connection" and "fixation" should be understood in a broad sense. For example, "fixation" includes fixed connections, removable connections, or integration, and may be mechanical or electrical connections, direct connections or indirect connections via another member, and may be internal connections or interactions between two elements unless explicitly limited. Those skilled in the art will be able to understand the specific meanings of the above terms in embodiments of the present invention depending on the specific context.

[0008] A robot 10 according to an embodiment of the present invention will be described. Figure 1 is a side view showing a robot system 1 equipped with a robot 10 according to this embodiment. Figure 2 is a partial cross-sectional view of the second arm 12b of the robot 10 shown in Figure 1. Figure 3 is an enlarged view of the area enclosed by the dashed line III in Figure 2. Figure 4 is a perspective view showing the support member 19 shown in Figure 2 fixed to the arm base 123 of the second arm 12b. Note that in Figures 2 and 3, some components of the robot 10 are shown in side views. Also, in Figure 4, the cover 124, the first endless belt 153, and the second endless belt 157, which will be described later, are omitted from the illustration.

[0009] As will be explained in more detail later, as shown in Figure 1, the base 11, first arm 12a, second arm 12b, shaft 13c, and end effector 13d of the robot 10 are connected in this order. Hereafter, in these connection paths, the side with the base 11 will be referred to as the "base end side" or "base end," and the opposite side will be referred to as the "tip side" or "tip."

[0010] Furthermore, in each figure, the X, Y, and Z axes are defined as three mutually orthogonal axes with respect to the robot 10's workspace. Each axis is represented by an arrow, with the tip of the arrow designated as the "+ side" and the base of the arrow as the "- side". In the following explanation, for example, "X-axis direction" includes both the positive and negative directions of the X axis. The same applies to the Y-axis and Z-axis directions.

[0011] Furthermore, in each figure, the direction parallel to the third axis A3, which is both the lifting and rotating axis of the shaft 13c described later, is defined as the Z-axis direction. Within the Z-axis direction, the direction in which the tip of the shaft 13c to which the end effector 13d is attached approaches the second arm 12b (Z-axis direction + side) is defined as "upward," "upward direction," or "upper side," and the opposite direction (Z-axis direction - side) is defined as "downward," "downward direction," or "lower side." In addition, the "upper end" of an object means the part that includes a certain range extending downward from the uppermost end of the object, and the "lower end" of an object means the part that includes a certain range extending upward from the lowest end of the object.

[0012] Furthermore, movement of shaft 13c toward the + side of the Z-axis is called "upward movement," movement toward the - side of the Z-axis is called "downward movement," and movement in the Z-axis direction is called "upward and downward movement." In this embodiment, the Z-axis direction is parallel to the vertical direction. However, the Z-axis direction does not necessarily have to be parallel to the vertical direction and may be inclined with respect to the vertical direction.

[0013] Further, in the present specification, "parallel" includes not only the case where two objects are strictly parallel, but also the case where, for example, one object is inclined within ±10° from the strictly parallel state of the two objects, that is, the case where the two objects are substantially parallel. Further, in the present specification, "perpendicular" includes not only the case where two objects are strictly perpendicular, but also the case where, for example, one object is inclined within ±10° from the strictly perpendicular state of the two objects, that is, the case where the two objects are substantially perpendicular.

[0014] A robot system 1 according to the present embodiment, as outlined with reference to FIG. 1, includes a robot 10 and a control device 30 that controls driving of each part of the robot 10.

[0015] The robot 10 is a horizontal articulated robot (SCARA robot). The robot 10 is used in various operations such as holding, transporting, assembling, processing, painting, and inspecting works such as electronic components, for example. However, the application and the type of operation of the robot 10 are not limited to the above.

[0016] The robot 10 includes a base 11, a robot arm 12 provided on the base 11, and a working head 13 provided at the distal end of the robot arm 12.

[0017] The base 11 is fixed to a support such as a floor, a ceiling, a side wall, a pillar, a beam, a mount, or a frame, and supports the robot arm 12. In the following, an example will be described in which the robot 10 is of a "ceiling-suspended type" in which the base 11 is attached to a support T1 located above the robot arm 12 in the vertical direction such as a ceiling. However, the robot 10 may be a wall-mounted type in which the base 11 is attached to a support located on the lateral side in the horizontal direction of the robot arm 12 such as a side wall, or may be a floor-standing type in which the base 11 is attached to a support located below the robot 10 in the vertical direction such as a floor.

[0018] The base 11 is provided with one or more connectors 11i for connecting equipment installed on the robot 10 to external devices such as the control device 30. The equipment installed on the robot 10 is not particularly limited, but examples include the first drive unit 14a, second drive unit 14b, third drive unit 14c, fourth drive unit 14d, and end effector 13d, which will be described later. Furthermore, the equipment installed on the robot 10 is not particularly limited, but may include, for example, sensors such as angle sensors and inertial sensors (not shown), cameras, solenoid valves, and electronic circuit boards such as power supply boards and control boards for these.

[0019] The equipment installed on the robot 10 and the connector 11i are connected by one or more linear members (not shown) that pass through the base 11 and the robot arm 12. The connector 11i and the external device are also connected by a linear member that passes outside the robot 10.

[0020] Examples of linear members include wiring and long, flexible hollow members. While not particularly limited, wiring can include electrical cables and optical cables. The external device transmits and receives signals to and from equipment installed on the robot 10 via the wiring and connector 11i. Furthermore, fluids such as air circulate inside the long, hollow member, allowing the external device to supply fluid to equipment installed on the robot 10, such as an end effector 13d, or to draw fluid from the surrounding equipment. Examples of long, hollow members include tubes, pipes, hoses, and ducts.

[0021] Connector 11i may be a connector capable of connecting electrical wiring, a connector capable of connecting optical wiring, or a connector capable of connecting a long hollow member. Multiple linear members may be bundled together. Also, a linear member may branch into multiple branches along the way. Furthermore, relay devices or relay connectors may be provided along the linear member.

[0022] The robot arm 12 is located below the base 11. The robot arm 12 has a first arm 12a provided on the base 11, a second arm 12b provided on the first arm 12a, a first joint 12c, and a second joint 12d.

[0023] The first arm 12a is located below the base 11. The base end of the first arm 12a is connected to the base 11 by a first joint 12c so as to be rotatable around a first axis A1. The first axis A1 is parallel to the Z-axis direction. The first arm 12a has an arm base 121a extending along a direction parallel to the XY plane, and a housing portion 121b protruding downward from the arm base 121a and housing the motor of the second drive unit 14b, which will be described later. However, the specific shape of the first arm 12a is not limited to the shape described above and shown in the figures.

[0024] The second arm 12b is located below the first arm 12a. The base end of the second arm 12b is rotatably connected to the tip of the first arm 12a by a second joint 12d, around a second axis A2. The second axis A2 is parallel to the first axis A1. Details of the structure of the second arm 12b will be described later.

[0025] The working head 13 is located at the tip of the second arm 12b. The working head 13 includes a spline nut 13a and a ball screw nut 13b, which are coaxially arranged on the third axis A3, and a shaft 13c through which the spline nut 13a and the ball screw nut 13b are inserted. The third axis A3 is parallel to the first axis A1 and the second axis A2.

[0026] The shaft 13c is also called the spline shaft or working shaft. The shaft 13c extends along the third axis A3. The shaft 13c is rotatable around the third axis A3 and can move up and down along the third axis A3. Specifically, the rotation of the spline nut 13a causes the shaft 13c to rotate around the third axis A3. In addition, the rotation of the ball screw nut 13b causes the shaft 13c to move up and down along the third axis A3.

[0027] An end effector 13d is attached to the lower end (tip) of the shaft 13c. The end effector 13d is detachable from the shaft 13c. The type of end effector 13d is not particularly limited, but examples include a hand, drill, and suction head.

[0028] An upper stopper 131 is provided at the upper end of the shaft 13c to prevent the shaft 13c from coming out of the second arm 12b downward when the shaft 13c is lowered. Similarly, a lower stopper 132 is provided at the lower end of the shaft 13c to prevent the shaft 13c from coming out of the second arm 12b upward when the shaft 13c is raised. The control program of the robot 10 limits the range in which the shaft 13c can descend so that the shaft 13c does not descend below a predetermined clearance above the upper stopper 131 from the sixth pulley 162 (described later). In addition, the control program of the robot 10 limits the range in which the shaft 13c can rise so that the shaft 13c does not rise above a predetermined clearance below the lower stopper 132 from the spline nut 13a. Hereinafter, the distance the shaft 13c moves in a direction parallel to the third axis A3 from the highest position to the lowest position of the shaft 13c will also simply be referred to as the "maximum vertical stroke length of the shaft 13c." In other words, the maximum vertical stroke length of the shaft 13c corresponds to the difference in the Z-axis direction between the highest position and the lowest position of the shaft 13c.

[0029] Furthermore, the lowest position of the shaft 13c may be when the upper stopper 131 is in contact with the upper surface of the sixth pulley 162. Also, the highest position of the shaft 13c may be when the lower stopper 132 is in contact with the lower surface of the spline nut 13a. In addition, the user of the robot 10 may further restrict the length to which the shaft 13c moves up and down, depending on the position of objects such as workpieces placed in the workspace, so that the length to which the shaft 13c moves up and down is shorter than the maximum possible stroke length of the shaft 13c. However, even in this case, the maximum possible stroke length of the shaft 13c means the original possible length of the shaft 13c before the user imposed any restrictions.

[0030] The robot 10 further comprises a first drive unit 14a, a second drive unit 14b, a third drive unit 14c, and a fourth drive unit 14d.

[0031] The first drive unit 14a rotates the first arm 12a around the first axis A1 relative to the base 11. The first drive unit 14a is housed within the base 11. The first drive unit 14a includes a motor that generates power to rotate the first arm 12a relative to the base 11, and a transmission unit (not shown) that transmits the rotation of the motor to the first arm 12a. The transmission unit is not particularly limited, but examples include a belt drive or other winding transmission device.

[0032] The second drive unit 14b rotates the second arm 12b relative to the first arm 12a around the second axis A2. The second drive unit 14b is housed within the first arm 12a. The second drive unit 14b includes a motor that generates power to rotate the second arm 12b relative to the first arm 12a, and a transmission unit (not shown) that transmits the rotation of the motor to the second arm 12b. As mentioned above, the motor is housed in the housing portion 121b of the first arm 12a. The transmission unit is similar to the one exemplified in the first drive unit 14a.

[0033] The third drive unit 14c rotates the shaft 13c around the third axis A3. The third drive unit 14c is housed within the second arm 12b. The third drive unit 14c includes a first motor 141a that generates power to rotate the shaft 13c, and a first transmission unit 150 that reduces the rotation of the first motor 141a and transmits it to the shaft 13c. A first brake 141b is provided on the output shaft of the first motor 141a. The first brake 141b is not particularly limited, but can be configured as, for example, a magnetic brake. Note that the robot 10 does not necessarily have to be provided with a first brake 141b. Details of the first transmission unit 150 will be described later.

[0034] The fourth drive unit 14d raises and lowers the shaft 13c along the third axis A3. The fourth drive unit 14d is housed within the second arm 12b. The fourth drive unit 14d includes a second motor 142a that generates power to raise and lower the shaft 13c, and a second transmission unit 160 that reduces the rotation of the second motor 142a and transmits it to the shaft 13c. A second brake 142b is provided on the output shaft of the second motor 142a. The second brake 142b is not particularly limited, but for example, it is the same as the one exemplified in the third drive unit 14c. Note that the robot 10 does not necessarily have to be provided with a second brake 142b. Details of the second transmission unit 160 will be described later.

[0035] The control device 30 is located outside the robot 10. However, the control device 30 may be housed in the base 11. The control device 30 comprises a storage unit, a control unit, and a communication unit. These are interconnected by a bus.

[0036] The memory unit consists of RAM (Random Access Memory) and ROM (Read Only Memory). The memory unit stores various programs and data, such as control programs that control the operation of the robot 10.

[0037] The control unit consists of at least one processor, such as a CPU (Central Processing Unit). The control unit reads and executes various programs stored in the memory unit.

[0038] The communication unit consists of various interfaces that enable communication with external devices such as the robot 10 and a teaching device (not shown). The communication unit transmits and receives information and signals to and from external devices. Communication by the communication unit may be conducted via a network such as a LAN (Local Area Network) or the Internet. Furthermore, the communication method may be wired or wireless.

[0039] Next, the structure of the second arm 12b will be described in detail. The second arm 12b includes a connecting portion 122a that is rotatably connected to the tip of the arm base 121a of the first arm 12a via a second joint 12d, and a housing 122b that houses the third drive unit 14c and the fourth drive unit 14d and is provided with a working head 13. The housing 122b includes an arm base 123 connected to the lower end of the connecting portion 122a, and a cover 124 that is positioned above the arm base 123 and to the side of the connecting portion 122a, and is detachably attached to the arm base 123.

[0040] In the following, the direction parallel to the first axis A1, the second axis A2, and the third axis A3 will also be referred to as "first direction D1," the direction perpendicular to the first direction D1 and moving from the second axis A2 toward the third axis A3 will also be referred to as "second direction D2," and the direction perpendicular to both the first direction D1 and the second direction D2 will also be referred to as "third direction D3." The first direction D1 is also the direction parallel to the Z axis. The second direction D2 and the third direction D3 are parallel to the XY plane and rotate with the rotation of the second arm 12b. Furthermore, each direction D1, D2, and D3 will be represented by an arrow, with the tip of the arrow being the "+ side" and the base of the arrow being the "- side." In the following, the length of the second arm 12b and the member installed on the second arm 12b in the first direction D1 will also be referred to as "height." In the following, the length of the second arm 12b and the member installed on the second arm 12b in the third direction D3 will also be referred to as the "width".

[0041] As shown in Figure 2, the connecting portion 122a is hollow and extends along the second axis A2. The connecting portion 122a is, for example, cylindrical in shape. The height of the connecting portion 122a is set such that when the second arm 12b is rotated with the shaft 13c in its highest position, the shaft 13c does not come into contact with the first arm 12a. Therefore, in this embodiment, the second arm 12b can rotate 360 ​​degrees relative to the first arm 12a.

[0042] However, the configuration of the connecting portion 122a is not limited to the configuration described above and shown in the illustration. For example, the upper end of the connecting portion 122a may be fixed to the arm base 121a of the first arm 12a, and the lower end of the connecting portion 122a may be rotatably connected around the second axis A2 to the base end of the arm base 123 of the second arm 12b via a second joint 12d. Alternatively, the connecting portion 122a may have a first portion fixed to the arm base 121a and extending along the first axis A1, and a second portion rotatably connected around the second axis A2 to the lower end of the first portion, fixed to the arm base 123, and extending along the first axis A1.

[0043] The arm base 123 is hollow. The shape of the arm base 123 is elongated and extends along the second direction D2, for example, a rectangular parallelepiped. The arm base 123 has an upper wall 123a, a lower wall 123b, and a side wall 123c. The upper wall 123a is parallel to the XY plane. The lower wall 123b is located below the upper wall 123a and is parallel to the XY plane. The side wall 123c is located between the upper wall 123a and the lower wall 123b and extends in the first direction D1 (Z-axis direction).

[0044] The connecting portion 122a is made of a material having sufficient strength to support the housing 122b. The arm base 123 is made of a material having sufficient strength to support the internal components of the second arm 12b and the shaft 13c. The materials used for the connecting portion 122a and the arm base 123 are not particularly limited, but include, for example, various metal materials, various resin materials, various ceramic materials, and materials that combine two or more of these. Among these, the metal materials are not particularly limited, but include, for example, iron, stainless steel, aluminum, copper, titanium, and alloys containing two or more of these.

[0045] The cover 124 is made of, for example, a plate material molded into a desired three-dimensional shape. The cover 124 covers the upper part of the arm base 123 and has an open shape at the bottom and on the side of the connecting part 122a. When the cover 124 is attached to the arm base 123, it forms an internal space between the cover 124 and the arm base 123.

[0046] Furthermore, the cover 124 is provided with one or more connectors 124i for connecting equipment installed on the outer surface of the second arm 12b or the shaft 13c to a linear member extending from the connector 11i of the base 11. The equipment installed on the outer surface of the second arm 12b or the shaft 13c is not particularly limited, but examples include an end effector 13d, a sensor (not shown), a camera, and a solenoid valve.

[0047] The cover 124 may be made of a material having strength comparable to that of the connecting portion 122a and the arm base 123, or it may be made of a material that is flexible or elastic enough to deform slightly when force is applied, or it may be made of a combination of these materials. The material used to make up the cover 124 is not particularly limited, but examples include materials similar to those exemplified for the connecting portion 122a and the arm base 123.

[0048] The end (tip) of the arm base 123 on the second direction D2+ side is provided with a through hole that penetrates the upper wall 123a and the lower wall 123b along the third axis A3. Similarly, the end of the cover 124 on the second direction D2+ side is provided with a through hole that penetrates the cover 124 in the thickness direction along the third axis A3. The shaft 13c is inserted through these through holes. When the shaft 13c is in its highest position, the upper end of the shaft 13c is exposed from the cover 124. When the shaft 13c is in its lowest position, the upper end of the shaft 13c is housed within the cover 124. However, the cover 124 may always have a shape that covers the upper end of the shaft 13c.

[0049] The spline nut 13a is located below the arm base 123. The ball screw nut 13b is located from above the arm base 123 through to the interior of the arm base 123. However, the specific positions of the spline nut 13a and the ball screw nut 13b are not limited to those described above.

[0050] The first motor 141a and the second motor 142a are located on the arm base 123 and inside the cover 124. Here, "the first motor 141a and the second motor 142a are located on the arm base 123" means that the majority of the first motor 141a and the second motor 142a are located on the arm base 123, and for example, a part of the first motor 141a or the second motor 142a may protrude into the interior of the arm base 123.

[0051] The first motor 141a is positioned between the connector 122a and the shaft 13c. The first motor 141a is fixed to the upper wall 123a of the arm base 123 via a support 141c, with its output shaft protruding downward from the housing of the first motor 141a. The first brake 141b is positioned on the lower side of the first motor 141a in the first direction D1, around the output shaft.

[0052] Furthermore, the second motor 142a is positioned between the first motor 141a and the shaft 13c. Therefore, the connection part 122a, the first motor 141a, the second motor 142a, and the shaft 13c are arranged in this order toward the second direction D2+. The second motor 142a is fixed to the upper wall 123a of the arm base 123 via a support 142c such that the output shaft protrudes downward from the housing of the second motor 142a, and the upper surface of the second motor 142a is positioned above the upper surface of the first motor 141a. The second brake 142b is positioned on the lower side of the second motor 142a in the first direction D1, around the output shaft.

[0053] The distance between the output shaft of the first motor 141a and the connector 122a in the second direction D2 is shorter than the distance between the output shaft of the first motor 141a and the shaft 13c in the second direction D2. Similarly, the distance between the output shaft of the second motor 142a and the connector 122a in the second direction D2 is shorter than the distance between the output shaft of the second motor 142a and the shaft 13c in the second direction D2. This allows the first motor 141a and the second motor 142a to be brought closer to the second axis A2. This allows the center of gravity of the second arm 12b, including the third drive unit 14c and the fourth drive unit 14d, to be brought closer to the second axis A2. This reduces the moment of inertia when the second arm 12b rotates. As a result, the second arm 12b can be rotated quickly, allowing the robot 10 to perform the desired operation quickly.

[0054] Furthermore, the first motor 141a and the second motor 142a are arranged side by side in the second direction D2. Therefore, the width of the second arm 12b can be reduced compared to the case where the first motor 141a and the second motor 142a are arranged side by side in the third direction D3. This makes it possible to suppress interference between the second arm 12b and objects placed in the robot 10's workspace when the second arm 12b rotates.

[0055] In a floor-standing robot, the first arm 12a and the second arm 12b are provided above the base 11, a shaft 13c that moves up and down along the third axis A3 is provided at the tip of the second arm 12b, and an end effector 13d is positioned below the shaft 13c. Therefore, in a floor-standing robot, the end effector 13d and the base 11 are located below the second arm 12b, so the second arm 12b may be restricted to rotating within an angular range where the end effector 13d of the shaft 13c and the base 11 do not interfere with each other. In contrast, in a ceiling-mounted robot 10, the first arm 12a, the second arm 12b, and the shaft 13c are positioned below the base 11. Therefore, in a ceiling-mounted robot 10, only the end effector 13d is located below the second arm 12b, so the rotatable angular range of the second arm 12b tends to be wider compared to a floor-standing robot, and in this embodiment it is 360 degrees.

[0056] In a ceiling-mounted robot 10, it is necessary to minimize the width of the second arm 12b so as to make full use of its rotatable angular range, and to minimize interference with objects placed in the robot's workspace. Therefore, minimizing the width of the second arm 12b is particularly beneficial in a ceiling-mounted robot 10.

[0057] Furthermore, the first transmission unit 150 is housed within the arm base 123. Here, "the first transmission unit 150 is housed within the arm base 123" means that the majority of the first transmission unit 150 is located within the arm base 123, and a part of the first transmission unit 150 may protrude outside the arm base 123. The first transmission unit 150 is composed of a two-stage reduction belt transmission device. The first transmission unit 150 includes a first pulley 151, a second pulley 152, a first endless belt 153, a shaft member 154, a third pulley 155, a fourth pulley 156, and a second endless belt 157.

[0058] In this specification, "pulley" refers to a driving or driven link in a belt drive system, and is also called a belt pulley. An "endless belt" is flexible, annular, and in a belt drive system, is wrapped around at least two pulleys, transmitting power from one pulley to the other. The pulleys 151, 152, 155, and 156 are not particularly limited, but examples include toothed pulleys, V-pulleys, and flat pulleys. The endless belts 153 and 157 are not particularly limited, but examples include toothed belts used in combination with toothed pulleys, V-belts used in combination with V-pulleys, and flat belts used in combination with flat pulleys.

[0059] The constituent materials for each pulley 151, 152, 155, 156 and the shaft member 154 are not particularly limited, but include, for example, various resin materials, various metal materials, various ceramic materials, and materials combining two or more of these. The constituent materials for the endless belts 153 and 157 are not particularly limited, but include, for example, various resin materials and various rubber materials. In this embodiment, the material of each pulley 151, 152, 155, and 156 is an alloy containing aluminum, so it can be made lighter compared to materials such as iron.

[0060] In the following, the "outer diameter" of pulleys 151, 152, 155, and 156 refers to the diameter of the portion of pulleys 151, 152, 155, and 156 around which the endless belts 153 and 157 are routed. Therefore, for example, if pulleys 151, 152, 155, and 156 are toothed pulleys, the "outer diameter" of pulleys 151, 152, 155, and 156 refers to the diameter of the portion where multiple teeth are provided. In this case, the "outer diameter" of pulleys 151, 152, 155, and 156 is not particularly limited, but examples include the diameter of the circle passing through the tips of multiple teeth, i.e., the "tip circle diameter" in JIS B 1859:2020, and the diameter of the circle passing through the pitch point, i.e., the "pitch circle diameter" in JIS B 1859:2020.

[0061] Furthermore, in the following, the "length in the first direction D1" of pulleys 151, 152, 155, and 156 refers to the length in the first direction D1 of the portion of pulleys 151, 152, 155, and 156 around which the endless belts 153 and 157 are wrapped. Therefore, for example, if pulleys 151, 152, 155, and 156 are toothed pulleys, the "length in the first direction D1" of pulleys 151, 152, 155, and 156 refers to the length in the first direction D1 of the portion where the teeth are provided. In this case, the "length in the first direction D1" of pulleys 151, 152, 155, and 156 is not particularly limited, but could be, for example, the "minimum tooth width" in JIS B 1859:2020. Furthermore, if pulleys 151, 152, 155, and 156 are flanged pulleys, the "length in the first direction D1" of pulleys 151, 152, 155, and 156 does not include the length of the flange in the first direction D1.

[0062] Furthermore, in the following, the "width" of endless belts 153 and 157 refers to the maximum length of endless belts 153 and 157 in the direction in which the rotation axes of pulleys 151, 152, 155, and 156 extend. Therefore, for example, if endless belts 153 and 157 are toothed belts, the width of endless belts 153 and 157 refers to the maximum length of the portion where teeth are provided. In this case, the "width" of endless belts 153 and 157 is not particularly limited, but refers to, for example, the "belt width" in JIS B 1859:2020.

[0063] In the upper wall 123a of the arm base 123, a through hole 123h is provided in the portion located below the first motor 141a and the second motor 142a in the first direction D1, and the upper wall 123a penetrates through the upper wall 123a in the thickness direction. The first pulley 151 corresponds to the first stage input pulley. The first pulley 151 is located inside the arm base 123 and below the first motor 141a in the first direction D1. The first pulley 151 is fixed to the output shaft of the first motor 141a on the arm base 123 via a connecting member 151a located in the through hole 123h. The first pulley 151 rotates in conjunction with the rotation of the output shaft of the first motor 141a.

[0064] As shown in Figures 1 and 2, the second pulley 152 corresponds to the first stage output pulley. The outer diameter of the second pulley 152 is larger than the outer diameter of the first pulley 151. The second pulley 152 is located within the arm base 123, between the first pulley 151 and the shaft 13c.

[0065] The third pulley 155 corresponds to the second stage input pulley. The outer diameter of the third pulley 155 is larger than that of the first pulley 151 and smaller than that of the second pulley 152. The third pulley 155 is located within the arm base 123 and is fixed coaxially to the second pulley 152.

[0066] The shaft member 154 corresponds to the axis of rotation of the second pulley 152 and the third pulley 155. The shaft member 154 extends along the first direction D1. The second pulley 152 and the third pulley 155 are provided on the shaft member 154. The shaft member 154 extends from above the arm base 123 and into the arm base 123.

[0067] In this embodiment, the shaft member 154, the second pulley 152, and the third pulley 155 are integrally formed. Hereinafter, the member that integrally constitutes the shaft member 154, the second pulley 152, and the third pulley 155 will also be referred to as the "intermediate member 150a". Note that two of the shaft member 154, the second pulley 152, and the third pulley 155 may be separate components, or three of them may be separate components.

[0068] The intermediate member 150a is rotatably supported on the arm base 123 of the second arm 12b via the first bearing 17a, the second bearing 17b, the bearing holder 18, and the support member 19. The first bearing 17a and the second bearing 17b each rotatably support the shaft member 154. The bearing holder 18 holds the first bearing 17a and the second bearing 17b. The support member 19 is fixed to the upper wall 123a of the arm base 123 and supports the bearing holder 18. The specific configuration and shape of the intermediate member 150a, the first bearing 17a, the second bearing 17b, the bearing holder 18, and the support member 19 will be described later.

[0069] The intermediate member 150a is located below the second motor 142a in the first direction D1. That is, the second pulley 152, the third pulley 155, and the shaft member 154 are located below the second motor 142a in the first direction D1. In this specification, "one of two objects is located below the other in the first direction D1" means that one is located below the other, and at least a portion of one overlaps with at least a portion of the other when viewed from the first direction D1.

[0070] As described above, since the intermediate member 150a is located below the second motor 142a in the first direction D1, the intermediate member 150a can be brought closer to the second axis A2 compared to cases where the intermediate member 150a is located between the second motor 142a and the shaft 13c when viewed from the first direction D1. This reduces the moment of inertia of the second arm 12b during rotation. Also, since the intermediate member 150a is located below the second motor 142a in the first direction D1, the width of the second arm 12b can be suppressed to increase compared to cases where the intermediate member 150a is located away from the second motor 142a in the third direction D3 when viewed from the first direction D1. In other words, the arrangement of the intermediate member 150a as described above suppresses an increase in the width of the second arm 12b while reducing the moment of inertia of the second arm 12b during rotation. And, as described above, in a ceiling-mounted robot 10, it is required to make the width of the second arm 12b as small as possible. Therefore, in the ceiling-mounted robot 10, it is particularly beneficial to position the intermediate member 150a below the second motor 142a in the first direction D1. In this embodiment, the intermediate member 150a is positioned coaxially with the second motor 142a. However, the intermediate member 150a does not necessarily have to be positioned coaxially with the second motor 142a.

[0071] The fourth pulley 156 corresponds to the second output pulley. The fourth pulley 156 is located within the arm base 123 and is coaxial with the shaft 13c and the spline nut 13a. The fourth pulley 156 is located above the spline nut 13a and is fixed to the spline nut 13a.

[0072] The first endless belt 153 corresponds to the first stage endless belt. The first endless belt 153 is routed around the first pulley 151 and the second pulley 152. The second endless belt 157 corresponds to the second stage endless belt. The second endless belt 157 is routed around the third pulley 155 and the fourth pulley 156. The first endless belt 153 and the second endless belt 157 are housed in the arm base 123 of the second arm 12b.

[0073] As described above, when the output shaft of the first motor 141a rotates, the first pulley 151 rotates. This causes the first endless belt 153 to rotate in a circular motion. This causes the intermediate member 150a, i.e., the shaft member 154, the second pulley 152, and the third pulley 155 to rotate. This causes the second endless belt 157 to rotate in a circular motion. This causes the fourth pulley 156 and the spline nut 13a to rotate. As a result, the shaft 13c rotates around the third axis A3.

[0074] Since the outer diameter of the second pulley 152 is larger than the outer diameter of the first pulley 151, and the outer diameter of the fourth pulley 156 is larger than the outer diameter of the third pulley 155, the rotation of the first motor 141a can be reduced in two stages and transmitted to the shaft 13c. This allows sufficient torque to be applied to the shaft 13c. In particular, when machining a workpiece while the end effector 13d is in contact with the workpiece and the end effector 13d is rotated, or when rotating an end effector 13d with a relatively large mass, the required torque is greater than when raising or lowering the shaft 13c. In this embodiment, since the first transmission unit 150 is configured as a two-stage reduction type belt transmission device, the rotation of the first motor 141a can be reduced, and sufficient torque can be applied to the shaft 13c and the end effector 13d. In addition, in gear devices such as reduction gears that include gears, the gears come into contact with each other and wear, so strong and heavy materials such as iron are used to improve wear resistance. In contrast, belt drive systems do not require wear resistance compared to gears, so it is possible to use lightweight materials, and if configured in this way, they are lighter than gear systems. Therefore, by configuring the first transmission section 150 with a belt drive system, sufficient torque can be applied to the shaft 13c and end effector 13d, and the moment of inertia of the second arm 12b during rotation can be reduced.

[0075] The reduction ratio of the first stage of the belt transmission device constituting the first transmission unit 150 is not particularly limited, but is preferably 1.2 or more and 5 or less, and more preferably 2.0 or more and 3 or less. The reduction ratio of the second stage of the belt transmission device constituting the first transmission unit 150 is not particularly limited, but is preferably 1.5 or more and 5 or less, and more preferably 2.0 or more and 3 or less.

[0076] The torque applied to the second endless belt 157 is greater than the torque applied to the first endless belt 153. In this embodiment, as shown in Figure 3, the length (height) of the third pulley 155 in the first direction D1 is greater than the length (height) of the second pulley 152 in the first direction D1. The width W2 of the second endless belt 157 is greater than the width W1 of the first endless belt 153. As a result, the contact area between the second endless belt 157 and the third pulley 155, and the contact area between the second endless belt 157 and the fourth pulley 156 can be increased compared to the case where the width W2 is less than or equal to the width W1. This prevents the second endless belt 157 from shifting position or slipping relative to the third pulley 155 and the fourth pulley 156. In particular, if the third pulley 155 and the fourth pulley 156 are toothed pulleys and the second endless belt 157 is a toothed belt, this can suppress tooth skipping of the second endless belt 157.

[0077] Here, the units of width W1 and width W2 are the same. In this case, W2 / W1 is not particularly limited, but is preferably 1.2 or more and 3 or less, and more preferably 1.4 or more and 2.7 or less. By setting W2 / W1 to be above the lower limit value above, the contact area between the second endless belt 157 and the third pulley 155 and the contact area between the second endless belt 157 and the fourth pulley 156 can be sufficiently secured. This prevents the second endless belt 157 from shifting position or slipping relative to the third pulley 155 and the fourth pulley 156. Furthermore, by setting W2 / W1 to be below the upper limit value above, the height of the first transmission section 150 can be suppressed while ensuring sufficient contact area between the first endless belt 153 and the first pulley 151 and the contact area between the first endless belt 153 and the second pulley 152. This prevents the height of the second arm 12b from increasing. By suppressing an increase in the height of the second arm 12b, it is possible to suppress a reduction in the maximum vertical stroke length of the shaft 13c. As a result, the types and range of tasks that the robot 10 can perform can be expanded. In addition, the range of choices for the end effector 13d attached to the shaft 13c and the workpiece to be worked on can be expanded.

[0078] As shown in Figure 2, the second transmission unit 160 is located above the arm base 123 and inside the cover 124. The second transmission unit 160 is composed of a single-stage reduction belt drive system and includes a fifth pulley 161, a sixth pulley 162, and a third endless belt 163.

[0079] The fifth pulley 161 corresponds to the input pulley. The fifth pulley 161 is fixed to the output shaft of the second motor 142a and rotates in conjunction with the output shaft of the second motor 142a. The sixth pulley 162 corresponds to the output pulley. The sixth pulley 162 is mounted coaxially with the shaft 13c and the ball screw nut 13b. The sixth pulley 162 is located above the ball screw nut 13b and is fixed to the ball screw nut 13b. The third endless belt 163 is wrapped around the fifth pulley 161 and the sixth pulley 162.

[0080] As described above, when the output shaft of the second motor 142a rotates, the fifth pulley 161 rotates. This causes the third endless belt 163 to rotate in a circular motion. This causes the sixth pulley 162 and the ball screw nut 13b to rotate. As a result, the shaft 13c rises or falls along the third axis A3 depending on the direction of rotation of the ball screw nut 13b. Since the outer diameter of the sixth pulley 162 is larger than the outer diameter of the fifth pulley 161, the rotation of the second motor 142a can be reduced and transmitted to the shaft 13c. This allows sufficient lifting speed and torque to be applied to the shaft 13c. Note that the outer diameters of the sixth pulley 162 and the fifth pulley 161 may be the same.

[0081] Next, the shapes and configurations of the intermediate member 150a, the first bearing 17a, the second bearing 17b, the bearing holder 18, and the support member 19 will be described. As shown in Figure 3, the shaft member 154 constituting the intermediate member 150a has a first cylindrical portion 154a that includes the lower end of the intermediate member 150a and extends along the first direction D1, and a second cylindrical portion 154b that is connected to the upper end of the first cylindrical portion 154a, has a smaller diameter than the diameter of the first cylindrical portion 154a and includes the upper end of the intermediate member 150a. That is, the shaft member 154 extends from the upper end to the lower end of the intermediate member 150a. However, the shape of the shaft member 154 is not particularly limited to the shape described above and shown in the figure. For example, the diameter of the shaft member 154 may be constant in the first direction D1.

[0082] The second cylindrical portion 154b is provided with a first bearing 17a and a second bearing 17b. In this embodiment, the lower end of the shaft member 154 is not supported by a bearing. The second cylindrical portion 154b is inserted through the inside of the first bearing 17a and the second bearing 17b and is fixed to the inner ring of the first bearing 17a and the inner ring of the second bearing 17b. The inner ring of the first bearing 17a is in contact with the upper surface of the first cylindrical portion 154a. The second bearing 17b is located above the first bearing 17a and is spaced apart from the first bearing 17a.

[0083] A collar 17c is positioned between the first bearing 17a and the second bearing 17b. The upper end of the second cylindrical portion 154b of the shaft member 154 protrudes upward from the second bearing 17b and is threaded. A nut 17d is screwed onto the upper end of the shaft member 154 and contacts the upper surface of the inner ring of the second bearing 17b. This allows preload to be applied to the first bearing 17a and the second bearing 17b. By providing two bearings on the upper part of the shaft member 154 in this way, axial wobble of the shaft member 154 during rotation can be suppressed even if only one of the ends of the shaft member 154 is supported. Furthermore, by applying preload to the first bearing 17a and the second bearing 17b, changes in the radial and axial position of the shaft member 154 can be suppressed.

[0084] The first bearing 17a and the second bearing 17b are each composed of rolling bearings, such as deep groove ball bearings, angular ball bearings, cylindrical roller bearings, and needle roller bearings, although they are not particularly limited. However, the first bearing 17a and the second bearing 17b may each be composed of sliding bearings. The types of the first bearing 17a and the second bearing 17b may be the same or different. The dimensions of the first bearing 17a and the second bearing 17b, such as the inner diameter, outer diameter, and width, may be the same or different.

[0085] Furthermore, the number of bearings provided on the shaft member 154 is not limited to two, as in this embodiment. The number of bearings provided on the shaft member 154 may be one, three, or more. Also, a second bearing 17b may be positioned below the first bearing 17a.

[0086] Let L1 be the distance between the first bearing 17a and the second bearing 17b, and L2 be the total length of the shaft member 154. The units of the distance L1 and the total length L2 are the same. In this case, L1 / L2 × 100 [%] is not particularly limited, but is preferably 5% or more and 10% or less, and more preferably 6% or more and 9.5% or less. By setting L1 / L2 × 100 to be above the lower limit value above, a sufficient distance L1 between the first bearing 17a and the second bearing 17b can be secured. As a result, even if only one of the ends of the shaft member 154 is supported, shaft wobble of the shaft member 154 during rotation can be suppressed. Furthermore, by setting L1 / L2 × 100 to be below the upper limit value above, sufficient length can be secured for the portion of the shaft member 154 where the second pulley 152 and the third pulley 155 are provided, and the total length L2 of the shaft member 154 can be suppressed from becoming too large. As a result, it is possible to suppress an increase in the height of the second arm 12b.

[0087] Here, the first condition is that the value of L1 / L2 × 100[%] is between 5% and 10%. The second condition is that the aforementioned W2 / W1 is between 1.2 and 3. It is preferable that the robot 10 satisfies both the first and second conditions. By satisfying both the first and second conditions, a synergistic effect is achieved between the two, and the effect of suppressing an increase in the height of the second arm 12b becomes more pronounced.

[0088] The first bearing 17a and the second bearing 17b are held in the bearing holder 18. The first bearing 17a and the second bearing 17b are provided on the second cylindrical portion 154b, which corresponds to the upper part of the shaft member 154, and the second pulley 152 and the third pulley 155 are provided on the first cylindrical portion 154a, which corresponds to the lower part of the shaft member 154. The third pulley 155 is located below the second pulley 152. Therefore, in this embodiment, the bearing holder 18, the second pulley 152, and the third pulley 155 are arranged in this order from top to bottom in the first direction D1.

[0089] As a result, as shown in Figure 2, the fourth pulley 156, which receives power from the third pulley 155 via the second endless belt 157, can be positioned in the lower part of the internal space of the arm base 123. If the third pulley 155 were positioned above the second pulley 152, the fourth pulley 156 would be positioned higher than the fourth pulley 156 in this embodiment, and consequently, the ball screw nut 13b, the second transmission unit 160, and the second motor 142a would be positioned higher. On the other hand, in this case, the position of the lower wall 123b of the second arm 12b would remain largely unchanged, thus shortening the maximum vertical stroke length of the shaft 13c. Therefore, by positioning the third pulley 155 below the second pulley 152, the maximum vertical stroke length of the shaft 13c can be increased compared to the case where the third pulley 155 is positioned above the second pulley 152.

[0090] As shown in Figure 3, at least a portion of the bearing holder 18 is housed in the arm base 123 of the second arm 12b. In this embodiment, the upper surface of the bearing holder 18 is flush with the upper surface of the upper wall 123a of the arm base 123. However, the upper surface of the bearing holder 18 may be located below or above the upper surface of the upper wall 123a of the arm base 123. The bearing holder 18 is cylindrical. The bearing holder 18 has a first cylindrical portion 181, a second cylindrical portion 182, and a tapered portion 183.

[0091] The first cylindrical portion 181 extends along the first direction D1. A first bearing 17a is located in the internal space of the first cylindrical portion 181, and the outer ring of the first bearing 17a is fixed to the first cylindrical portion 181. At least a portion of the first cylindrical portion 181 is housed in a recess 152a of the second pulley 152, which will be described later.

[0092] The tapered portion 183 is located between the first cylindrical portion 181 and the second cylindrical portion 182 and extends along the first direction D1. The tapered portion 183 is hollow and is connected to the upper end of the first cylindrical portion 181 and the lower end of the second cylindrical portion 182. The outer diameter of the tapered portion 183 gradually increases towards the top. The tapered portion 183 is exposed from the recess 152a. However, the tapered portion 183 may be housed within the recess 152a.

[0093] The second cylindrical portion 182 is connected to the upper end of the tapered portion 183 and extends along the first direction D1. The second cylindrical portion 182 is connected to the first cylindrical portion 181 via the tapered portion 183. A second bearing 17b is located in the internal space of the second cylindrical portion 182, and the outer ring of the second bearing 17b is fixed to the second cylindrical portion 182. The outer diameter of the second cylindrical portion 182 is larger than the outer diameter of the first cylindrical portion 181. The second cylindrical portion 182 is exposed from the recess 152a.

[0094] The upper end of the shaft member 154 protrudes upward from the second cylindrical portion 182. That is, the end of the shaft member 154 opposite to the end where the second pulley 152 and the third pulley 155 are provided protrudes from the bearing holder 18. This allows the bearing holder 18 to be positioned lower relative to the shaft member 154 compared to the case where the upper end of the shaft member 154 is covered by the bearing holder 18. Therefore, the length of the assembly of the intermediate member 150a and the bearing holder 18 in the first direction D1 can be shortened compared to the case where the upper end of the shaft member 154 is covered by the bearing holder 18. In addition, the process of screwing the nut 17d onto the upper end of the shaft member 154 and fixing the inner ring of the first bearing 17a and the inner ring of the second bearing 17b to the shaft member 154 becomes easier.

[0095] The second cylindrical portion 182 is fixed to the support member 19 by screws or the like. As mentioned above, the outer diameter of the second cylindrical portion 182 is larger than the outer diameter of the first cylindrical portion 181. Therefore, while housing the first cylindrical portion 181 in the recess 152a of the second pulley 152 (described later), sufficient radial wall thickness of the second cylindrical portion 182 can be ensured, and screw holes or the like for fixing to the support member 19 can be provided in the second cylindrical portion 182. In addition, the rigidity of the joint between the second cylindrical portion 182 and the support member 19 can be increased. However, the second cylindrical portion 182 may be directly fixed to the second arm 12b instead of being indirectly fixed to the second arm 12b via the support member 19.

[0096] The bearing holder 18 is made of a material having sufficient strength to hold the first bearing 17a and the second bearing 17b. Such materials are not particularly limited, but examples include various metal materials and various resin materials.

[0097] However, the shape of the bearing holder 18 is not limited to the shape described above and shown in the illustration. For example, the bearing holder 18 may not have a tapered portion 183, and may have a stepped portion created by the difference in outer diameter between the first cylindrical portion 181 and the second cylindrical portion 182. Alternatively, the shape of the bearing holder 18 may be cylindrical with a constant outer diameter in the first direction D1.

[0098] As shown in Figures 3 and 4, the support member 19 is parallel to the XY plane and is a flat plate with the third direction D3 as its longitudinal direction. The support member 19 is positioned on the upper wall 123a of the arm base 123 of the second arm 12b and is fixed to the upper wall 123a of the arm base 123. Specifically, the end of the support member 19 on the third direction D3- side is fixed to the part of the arm base 123 located on the third direction D3- side of the through hole 123h by screws or the like. The end of the support member 19 on the third direction D3+ side is fixed to the part of the arm base 123 located on the third direction D3+ side of the through hole 123h by screws or the like.

[0099] A through hole 19h extending along the first direction D1 is provided approximately in the center of the support member 19 in the third direction D3 and the second direction D2. As shown in Figure 3, the upper surface of the second cylindrical portion 182 of the bearing holder 18 is in contact with the area of ​​the lower surface of the support member 19 surrounding the through hole 19h, and the second cylindrical portion 182 is fixed to the support member 19 by screws or the like. In this way, the support member 19 can support the bearing holder 18 so as to suspend it from the upper wall 123a of the arm base 123. This makes it possible to shorten the height of the arm base 123 compared to when the support member 19 is provided on the lower wall 123b of the arm base 123.

[0100] Furthermore, the shaft member 154 is inserted through the through hole 19h of the support member 19, and the upper end of the shaft member 154 protrudes above the support member 19. Therefore, the support member 19 can be positioned as low as possible relative to the shaft member 154. This suppresses an increase in the overall height of the assembly consisting of the intermediate member 150a, the first bearing 17a, the second bearing 17b, the bearing holder 18, and the support member 19.

[0101] The support member 19 is made of a material having sufficient strength to support the bearing holder 18. While not particularly limited, such materials include various metal materials and various resin materials.

[0102] The shape of the support member 19 is not limited to the shape described above or shown in the illustration. For example, the support member 19 may be disc-shaped. Also, the support member 19 may be fixed to the side wall 123c of the arm base 123, or to the lower wall 123b of the arm base 123.

[0103] The second pulley 152 is positioned slightly below the upper end of the first cylindrical portion 154a of the shaft member 154. On the upper surface of the second pulley 152, around the shaft member 154, there is an annular recess 152a that is recessed downward. That is, the second pulley 152 has an annular recess 152a formed coaxially with the second pulley 152 on its inside. As described above, at least a portion of the first cylindrical portion 181 of the bearing holder 18 is inserted into the recess 152a. At least a portion of the first cylindrical portion 181 overlaps with the first endless belt 153 that is wrapped around the second pulley 152 when viewed from a direction perpendicular to the first direction D1, such as the second direction D2 or the third direction D3. This makes it possible to suppress an increase in the height of the assembly of the intermediate member 150a and the bearing holder 18 compared to the case where the bearing holder 18 is positioned above the second pulley 152. Therefore, it is possible to suppress an increase in the height of the arm base 123 of the second arm 12b. This prevents a reduction in the maximum vertical stroke length of the shaft 13c.

[0104] The third pulley 155 is connected to the lower end of the second pulley 152 and the first cylindrical portion 154a of the shaft member 154.

[0105] In this embodiment, the bearing holder 18, the second pulley 152, and the third pulley 155 are arranged in this order from top to bottom in the first direction D1. However, the order in which they are arranged is not limited to this order.

[0106] For example, the second pulley 152 may be positioned below the third pulley 155. The bearing holder 18 may be positioned above the second pulley 152 and the third pulley 155, or below the second pulley 152 and the third pulley 155. If the bearing holder 18 is positioned below the second pulley 152 and the third pulley 155, a recess may be provided on the lower of the two pulleys, and at least a portion of the bearing holder 18 may be housed in the recess. If the bearing holder 18 is positioned above the second pulley 152 and the third pulley 155, a recess may be provided on the upper of the two pulleys, and at least a portion of the bearing holder 18 may be housed in the recess. Furthermore, in this configuration, when viewed from a direction perpendicular to the first direction D1, the bearing holder 18 should overlap with the part of the first endless belt 153 and the second endless belt 157 that is closer to the recess 152a. Even in this configuration, it is possible to suppress an increase in the height of the assembly of the intermediate member 150a, the first bearing 17a, and the bearing holder 18.

[0107] However, the recess 152a is not required to be provided in either the second pulley 152 or the third pulley 155. Also, bearings and bearing holders 18 may be provided at both ends of the shaft member 154. In this case, the recess 152a may be provided in both the second pulley 152 and the third pulley 155, and at least a part of the bearing holder 18 corresponding to each recess 152a may be housed there. Furthermore, the recess 152a of the second pulley 152 may be provided on the lower surface of the second pulley 152 around the shaft member 154 in an annular shape that is recessed upward. In this case, the shaft member 154 and the second pulley 152 may be constructed as separate parts, and screw holes or the like for fixing the second pulley 152 to the shaft member 154 can be provided in the recess 152a. In this case, the shaft member 154 and the third pulley 155 can be configured as separate components, and a screw hole or the like can be provided on the upper part of the third pulley 155 for fixing the third pulley 155 to the shaft member 154. With this configuration, the shaft member 154 can be standardized, and the outer diameters of the second pulley 152 and the third pulley 155 can be easily changed by changing the second pulley 152 and the third pulley 155 fixed to the shaft member 154. In addition, the second motor 142a may be positioned on the second direction D2- side than the first motor 141a. In this case, the second transmission unit 160 should be positioned so as not to interfere with the first motor 141a or the first transmission unit 150, and the intermediate member 150a should be positioned below the second motor 142a in the first direction D1.

[0108] As described above, the robot 10 according to this embodiment includes a base 11, a first arm 12a, a second arm 12b, a shaft 13c, a first motor 141a, a second motor 142a, a first transmission unit 150, and a second transmission unit 160. The first arm 12a is provided on the base 11 and is rotatable around a first axis A1 relative to the base 11. The second arm 12b is provided on the first arm 12a and is rotatable around a second axis A2 parallel to the first axis A1 relative to the first arm 12a. The shaft 13c is provided at the tip of the second arm 12b and is rotatable around a third axis A3 parallel to the second axis A2 and is movable up and down along the third axis A3. The first motor 141a is provided on the second arm 12b and generates power to rotate the shaft 13c. The second motor 142a is mounted on the second arm 12b and generates power to raise and lower the shaft 13c. The first transmission unit 150 is mounted on the second arm 12b and reduces the rotation of the first motor 141a and transmits it to the shaft 13c. The second transmission unit 160 is mounted on the second arm 12b and transmits the rotation of the second motor 142a to the shaft 13c. The direction parallel to the third axis A3 is defined as the first direction D1. The first transmission unit 150 includes a first pulley 151, a second pulley 152, a first endless belt 153, a third pulley 155, a fourth pulley 156, and a second endless belt 157. The first pulley 151 is located below the first motor 141a in a first direction D1 and is fixed to the output shaft of the first motor 141a. The second pulley 152 is located between the first pulley 151 and the shaft 13c. The first endless belt 153 is wrapped around the first pulley 151 and the second pulley 152. The third pulley 155 is fixed coaxially to the second pulley 152. The fourth pulley 156 is provided coaxially with the shaft 13c. The second endless belt 157 is wrapped around the third pulley 155 and the fourth pulley 156. The second pulley 152 and the third pulley 155 are located on the lower side of the second motor 142a in the first direction D1.

[0109] Thus, the first transmission unit 150 is composed of a belt drive system including four pulleys 151, 152, 155, and 156 and two endless belts 153 and 157. Therefore, the rotation of the first motor 141a can be reduced, and sufficient torque can be applied to the shaft 13c. In addition, because the first transmission unit 150 is composed of a belt drive system, the first transmission unit 150 can be made lighter compared to cases where the first transmission unit 150 is composed of a gear system, etc. This makes it possible to reduce the moment of inertia of the second arm 12b when it rotates.

[0110] Furthermore, the second pulley 152 and the third pulley 155 are positioned below the second motor 142a in the first direction D1. This allows the second pulley 152 and the third pulley 155 to be positioned closer to the second axis A2 compared to cases where they are located between the second motor 142a and the shaft 13c when viewed from the first direction D1. This reduces the moment of inertia of the second arm 12b during rotation. In addition, this suppresses an increase in the width of the second arm 12b compared to cases where the second pulley 152 and the third pulley 155 are located away from the second motor 142a in the third direction D3 when viewed from the first direction D1. In other words, it is possible to reduce the moment of inertia of the second arm 12b during rotation while suppressing an increase in the width of the second arm 12b.

[0111] Furthermore, the robot 10 according to this embodiment further comprises a shaft member 154, a first bearing 17a, and a bearing holder 18. The shaft member 154 is located below the second motor 142a in the first direction D1, extends in the first direction D1, and is provided with a second pulley 152 and a third pulley 155. The first bearing 17a rotatably supports the shaft member 154. The bearing holder 18 holds the first bearing 17a. A recess 152a is provided in one of the second pulley 152 and the third pulley 155. At least a portion of the bearing holder 18 is housed in the recess 152a. When viewed from a direction perpendicular to the first direction D1, the bearing holder 18 and the part of the first endless belt 153 and the second endless belt 157 closer to the recess 152a overlap. In this embodiment, the one of the first endless belt 153 and the second endless belt 157 that is closer to the recess 152a is the first endless belt 153. Therefore, the height of the assembly of the shaft member 154, the first bearing 17a, and the bearing holder 18 can be suppressed from increasing. This also suppresses an increase in the height of the second arm 12b. As a result, the maximum vertical stroke length of the shaft 13c can be suppressed from decreasing.

[0112] Furthermore, the end of the shaft member 154 opposite to the end where the second pulley 152 and the third pulley 155 are provided protrudes from the bearing holder 18. Therefore, compared to the case where the end of the shaft member 154 is covered by the bearing holder 18, it is possible to suppress an increase in the height of the assembly of the shaft member 154 and the bearing holder 18.

[0113] The bearing holder 18 also has a first cylindrical portion 181 and a second cylindrical portion 182. The first cylindrical portion 181 extends in a first direction D1 and at least a portion of it is housed in a recess 152a. The second cylindrical portion 182 is connected to the first cylindrical portion 181, is exposed from the recess 152a, extends in the first direction D1, has a larger outer diameter than the outer diameter of the first cylindrical portion 181, and is connected to the second arm 12b. Therefore, at least a portion of the first cylindrical portion 181 can be housed in the recess 152a, while screw holes or the like for indirectly or directly connecting the bearing holder 18 to the second arm 12b can be provided in the second cylindrical portion 182. Furthermore, the rigidity of the second cylindrical portion connected indirectly or directly to the second arm 12b can be increased.

[0114] Furthermore, the bearing holder 18, the second pulley 152, and the third pulley 155 are arranged in this order from top to bottom in the first direction D1. Therefore, the fourth pulley 156, which receives power from the third pulley 155 via the second endless belt 157, can be positioned below the second arm 12b. This allows for a longer maximum vertical stroke length of the shaft 13c compared to the case where the third pulley 155 is positioned above the second pulley 152.

[0115] Furthermore, the robot 10 according to this embodiment further includes a second bearing 17b housed in a bearing holder 18 and rotatably supporting the shaft member 154. When the distance between the first bearing 17a and the second bearing 17b is L1 and the total length of the shaft member 154 is L2, L1 / L2 × 100 [%] is 5% or more and 10% or less. In this way, by setting L1 / L2 × 100 to be greater than or equal to the lower limit value mentioned above, a sufficient distance L1 between the first bearing 17a and the second bearing 17b can be secured. As a result, axial wobble of the shaft member 154 during rotation can be suppressed. Furthermore, by setting L1 / L2 × 100 to be less than or equal to the upper limit value mentioned above, sufficient length can be secured for the portion of the shaft member 154 where the second pulley 152 and the third pulley 155 are installed, thereby suppressing an increase in the overall length L2 of the shaft member 154. This suppresses an increase in the height of the second arm 12b. As a result, a reduction in the maximum vertical stroke length of the shaft 13c can be suppressed.

[0116] Furthermore, the second arm 12b extends in a direction perpendicular to the second axis A2, is hollow, and includes an arm base 123 that accommodates at least a portion of the bearing holder 18, and a support member 19 fixed to the upper wall 123a of the arm base 123 and supporting the bearing holder 18. Therefore, the bearing holder 18 can be supported by suspending it from the upper wall 123a of the arm base 123. This allows the height of the arm base 123 to be shortened compared to cases where the support member 19 is provided on the lower wall 123b of the arm base 123. As a result, the reduction in the maximum vertical stroke length of the shaft 13c can be suppressed. In addition, because the arm base 123 is hollow, the moment of inertia of the second arm 12b during rotation can be further reduced.

[0117] Furthermore, the first transmission unit 150 is housed in the arm base 123. The second transmission unit 160 is located above the arm base 123. Therefore, the assembly of the first transmission unit 150 to the second arm 12b and the assembly of the second transmission unit 160 can be performed separately. This simplifies the assembly and maintenance of the robot 10.

[0118] Furthermore, when the width of the first endless belt 153 in the first direction D1 is W1 and the width of the second endless belt 157 in the first direction D1 is W2, W2 / W1 is between 1.2 and 3. By setting W2 / W1 to be greater than or equal to the lower limit value mentioned above, the width W2 of the second endless belt 157 can be sufficiently secured. This prevents the second endless belt 157 from shifting position relative to the third pulley 155 and the fourth pulley 156, or from slipping. Furthermore, if the third pulley 155 and the fourth pulley 156 are toothed pulleys and the second endless belt 157 is a toothed belt, skipping teeth on the second endless belt 157 can be suppressed. Additionally, by setting W2 / W1 to be less than or equal to the upper limit value mentioned above, the width W1 of the first endless belt 153 can be sufficiently secured, while preventing the length of the first direction D1 of the first transmission unit 150 from increasing. This prevents the height of the second arm 12b from increasing.

[0119] Furthermore, the robot 10 according to this embodiment is a ceiling-mounted robot. In a ceiling-mounted robot 10, it is necessary to reduce the width of the second arm 12b to minimize interference with objects placed in the robot's workspace. Therefore, in a ceiling-mounted robot 10, it is particularly beneficial to position the second pulley 152 and the third pulley 155 below the second motor 142a in the first direction D1.

[0120] Although the robot according to the present invention has been described in the illustrated embodiment, the present invention is not limited thereto. Furthermore, each part of the robot can be replaced with any structure capable of performing similar functions. In addition, any structure may be added to the robot. [Explanation of Symbols]

[0121] 1...Robot system, 10...Robot, 11...Base, 11i...Connector, 12...Robot arm, 12a...First arm, 12b...Second arm, 12c...First joint, 12d...Second joint, 13...Working head, 13a...Spline nut, 13b...Ball screw nut, 13c...Shaft, 13d...End effector, 14a...First drive unit, 14b...Second drive unit, 14c...Third drive unit, 14d...Fourth drive unit Moving part, 17a...First bearing, 17b...Second bearing, 17c...Collar, 17d...Nut, 18...Bearing holder, 19...Support member, 30...Control device, 121a...Arm base, 121b...Housing section, 122a...Connecting section, 122b...Housing, 123...Arm base, 123a...Upper wall, 123b...Lower wall, 123c...Side wall, 123h...Through hole, 124...Cover, 131...Upper stopper, 132...Lower stopper, 141a...First motor, 141b...First brake, 141c...Support, 142a...Second motor, 142b...Second brake, 142c...Support, 150...First transmission section, 150a...Intermediate member, 151...First pulley, 151a...Connecting member, 152...Second pulley, 152a...Recess, 153...First endless belt, 154...Shaft member, 154a...First cylindrical section, 154b...Second cylindrical section, 155...Third pulley -, 156...4th pulley, 157...2nd endless belt, 160...2nd transmission section, 161...5th pulley, 162...6th pulley, 163...3rd endless belt, 181...1st cylindrical section, 182...2nd cylindrical section, 183...Tapered section, A1...1st axis, A2...2nd axis, A3...3rd axis, D1...1st direction, D2...2nd direction, D3...3rd direction, L1...separation distance, L2...total length, T1...support, W1...width, W2...width

Claims

1. Base and, A first arm is provided on the base and is rotatable about a first axis relative to the base, A second arm is provided on the first arm and is rotatable around a second axis parallel to the first axis relative to the first arm, A shaft provided at the tip of the second arm, which is rotatable around a third axis parallel to the second axis and can move up and down along the third axis, A first motor is provided on the second arm and generates power to rotate the shaft, A second motor is provided on the second arm and generates power to raise and lower the shaft, A first transmission unit is provided on the second arm and reduces the rotation of the first motor and transmits it to the shaft, A second transmission unit is provided on the second arm and transmits the rotation of the second motor to the shaft, Equipped with, When the direction parallel to the third axis is defined as the first direction, The first transmission unit is, A first pulley is located on the lower side of the first motor in the first direction and is fixed to the output shaft of the first motor, A second pulley is located between the first pulley and the shaft, The first endless belt is wrapped around the first pulley and the second pulley, A third pulley is fixed coaxially to the second pulley, A fourth pulley is provided coaxially with the aforementioned shaft, The second endless belt is wrapped around the third pulley and the fourth pulley, It has, The second pulley and the third pulley are located on the lower side of the second motor in the first direction. A robot characterized by the following features.

2. A shaft member located below the second motor in the first direction, extending in the first direction, and on which the second pulley and the third pulley are provided, A first bearing that rotatably supports the aforementioned shaft member, A bearing holder that holds the first bearing, Furthermore, One of the second pulley and the third pulley is provided with a recess, At least a portion of the bearing holder is housed in the recess, The robot according to claim 1, wherein, when viewed from a direction perpendicular to the first direction, the bearing holder and the part of the first endless belt and the second endless belt that is closer to the recess overlap.

3. The robot according to claim 2, wherein the end of the shaft member located opposite to the end on which the second pulley and the third pulley are provided protrudes from the bearing holder.

4. The aforementioned bearing holder is A first cylindrical portion extending in the first direction and at least a portion of which is housed in the recess, The robot according to claim 2 or 3, further comprising: a second cylindrical portion connected to the first cylindrical portion, exposed from the recess, extending in the first direction, having an outer diameter larger than the outer diameter of the first cylindrical portion, and connected to the second arm.

5. The robot according to claim 2 or 3, wherein the bearing holder, the second pulley, and the third pulley are arranged in this order from top to bottom in the first direction.

6. The bearing holder further comprises a second bearing housed within it, which rotatably supports the shaft member, The robot according to claim 2 or 3, wherein when the distance between the first bearing and the second bearing is L1 and the total length of the shaft member is L2, L1 / L2 × 100 [%] is 5% or more and 10% or less.

7. The second arm is, An arm base extending in a direction perpendicular to the first direction, being hollow, and housing at least a portion of the bearing holder, The robot according to claim 2 or 3, further comprising a support member fixed to the upper wall of the arm base and supporting the bearing holder.

8. The first transmission unit is housed within the arm base, The robot according to claim 7, wherein the second transmission unit is located above the arm base.

9. The robot according to any one of claims 1 to 3, wherein when the width of the first endless belt in the first direction is W1 and the width of the second endless belt in the first direction is W2, W2 / W1 is 1.2 or more and 3 or less.

10. A ceiling-mounted robot, as described in any one of claims 1 to 3.

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