robot

Abstract

We provide a robot that can utilize the maximum vertical stroke length of the shaft. [Solution] A robot comprising: a base having a housing; a first arm rotatable about a first axis relative to the base; a second arm rotatable about a second axis relative to the first arm; a first motor provided in the housing and generating power to rotate the first arm relative to the base; a reduction gear provided in the housing and reducing the rotation of the first motor; and a second motor generating power to rotate the second arm relative to the first arm, wherein the housing has a bottom plate portion provided with a first through hole, a part of the reduction gear is arranged in the first through hole, and the first arm has a first arm base extending in a direction perpendicular to the first axis, and a housing portion protruding downward from the first arm base, housing the second motor, and separated from the second arm.

Description

Technical Field

[0001] The present invention relates to a robot.

Background Art

[0002] Patent Document 1 discloses a ceiling-suspended robot. The robot includes a base, a first arm disposed below the base and rotatable relative to the base, a second arm disposed below the first arm and rotatable relative to the first arm, and a shaft disposed on the second arm that is rotatable and capable of moving up and down. In a ceiling-suspended robot, it is known that the first arm is arranged spaced downward from the base to prevent interference between the first arm and the base, and interference between the first arm and a support body such as a ceiling when the first arm is rotated relative to the base.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the greater the distance between the first arm and the base, the further downward the second arm is arranged, and the lower end portion of the shaft provided on the second arm approaches objects such as a workpiece and a floor arranged below the shaft. As a result, the shaft can only move up and down by a length shorter than the maximum stroke length that is the originally possible vertical movement length, and the maximum possible vertical movement stroke length of the shaft may not be fully utilized in some cases.

Means for Solving the Problems

[0005] A robot according to an application example of the present invention comprises: a base having a housing, a first arm disposed below the base and rotatable about a first axis relative to the base, A second arm is provided below 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 movable up and down along a third axis parallel to the second axis, A first motor is provided within the housing and generates power to rotate the first arm relative to the base, A reduction gear is provided within the housing and reduces the rotation of the first motor and transmits the power to the first arm, A second motor generates power to rotate the second arm relative to the first arm, A third motor generates power to raise and lower the aforementioned shaft, Equipped with, The housing has a bottom plate portion provided with a first through hole extending along the first axis, A portion of the reduction gear is located within the first through-hole. The first arm includes a first arm base extending in a direction perpendicular to the first axis, and a housing portion protruding downward from the first arm base, housing the second motor, and spaced apart from the second arm. [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 cross-sectional view of the base of the robot shown in Figure 1. [Figure 3] This is a cross-sectional view along the line III-III in Figure 1. [Figure 4] This is a cross-sectional view along the line IV-IV in Figure 1. [Figure 5] This is a cross-sectional view along the VV line in Figure 1. [Figure 6] This is a side view showing the maximum stroke length of the shaft. [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 cross-sectional view of the base 11 of the robot 10 shown in Figure 1. Figure 3 is a cross-sectional view along the line III-III in Figure 1. Figure 4 is a cross-sectional view along the line IV-IV in Figure 1. Figure 5 is a cross-sectional view along the line VV in Figure 1. Figure 6 is a side view showing the maximum stroke length S of the shaft 13c. Note that in Figure 2, some elements of the robot 10 are shown in side view. Also, in Figure 3, the holder 216 of the bearing 212, which will be described later, is not shown.

[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 the vertical 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." Also, movement of the shaft 13c toward the Z-axis direction + side is called "upward," movement toward the Z-axis direction - side is called "downward," and movement in the Z-axis direction is called "upward and downward." In addition, the "upper end" of an object means the part that includes a certain range downward from the uppermost end of the object, and the "lower end" of an object means the part that includes a certain range upward from the lowest end of the object. 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.

[0012] Furthermore, in this specification, “parallel” includes not only cases where two objects are strictly parallel, but also cases where one object is tilted by, for example, ±10° from a strictly parallel state, i.e., substantially parallel. Furthermore, in this specification, “orthogonal” includes not only cases where two objects are strictly orthogonal, but also cases where one object is tilted by, for example, ±10° from a strictly orthogonal state, i.e., substantially orthogonal.

[0013] The robot system 1 according to this embodiment, as outlined with reference to Figure 1, comprises a robot 10 and a control device 30 that controls the driving of each part of the robot 10.

[0014] The robot 10 is a ceiling-mounted horizontal articulated robot (SCARA robot). The robot 10 is used in various operations such as holding, transporting, assembling, processing, painting, and inspecting workpieces such as electronic components, for example. However, the application and the type of operation of the robot 10 are not limited to the above.

[0015] The robot 10 includes a base 11, a robot arm 12 provided below the base 11, and a work head 13 provided at the distal end of the robot arm 12.

[0016] The base 11 is attached to a support T1 located vertically above the robot arm 12, such as a ceiling, a pillar, a beam, or a frame. The robot 10 is suspended from the support T1. The base 11 has a box-shaped housing 11a. The housing 11a includes a housing main body 111 with an open lower portion, and a bottom plate portion 112 that covers the opening at the lower portion of the housing main body 111.

[0017] The housing main body 111 includes a top plate portion 111a parallel to the X-Y plane, and a side wall portion 111b extending downward from the outer peripheral edge of the top plate portion 111a. The top plate portion 111a is provided with one or more connectors 11i for connecting equipment installed on the robot 10 to an external device such as the control device 30. The equipment installed on the robot 10 is not particularly limited, and examples thereof include a first drive unit 14, a second drive unit 15, a third drive unit 16, a fourth drive unit 17, and an end effector 13d, which will be described later. Furthermore, the equipment installed on the robot 10 is not particularly limited, and may include, for example, sensors such as an angle sensor and an inertia sensor (not shown), a camera, a solenoid valve, and electronic boards such as power supply boards and control boards thereof.

[0018] The equipment installed on the robot 10 and the connectors 11i are connected by one or more linear members (not shown) that pass through the inside of the base 11 and the inside of the robot arm 12. In addition, the connectors 11i and the external device are connected by a linear member that passes through the outside of the robot 10.

[0019] Examples of linear members include wiring and long, flexible hollow members. Examples of wiring include electrical wiring such as electrical cables and optical wiring such as optical fibers. The external device transmits and receives signals to and from equipment installed on the robot 10 via the wiring and connector 11i. In addition, fluid such as air flows inside the long, hollow member, and the external device can supply fluid to equipment installed on the robot 10, such as an end effector 13d, or draw in fluid from around the equipment via the long, hollow member. Examples of long, hollow members are not particularly limited, but include tubes, pipes, hoses, and ducts.

[0020] 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. Furthermore, a linear member may branch into multiple branches along its length. Relay devices or relay connectors may also be provided along the linear member.

[0021] The bottom plate portion 112 is a flat plate parallel to the XY plane. The bottom plate portion 112 is fixed to the lower end of the housing body 111 by screws or the like. In a plan view, the outer edge of the bottom plate portion 112 protrudes outward from the housing body 111. The upper surface of the outer edge of the bottom plate portion 112 is in contact with the lower surface of the support T1, and the outer edge of the bottom plate portion 112 is fixed to the support T1 by screws or the like.

[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 and a second arm 12b provided on the first arm 12a.

[0023] The first arm 12a is located below the base 11. The base end of the first arm 12a is rotatably connected to the base 11 around the first axis A1. The first axis A1 is parallel to the Z-axis direction.

[0024] The first arm 12a has a first arm base 121a and a housing portion 121b. The first arm base 121a extends in a direction perpendicular to the first axis A1, that is, in a direction parallel to the XY plane. As shown in Figure 4, the first arm base 121a is hollow and, for example, has the shape of a rectangular parallelepiped with rounded corners. The side walls of the first arm base 121a have a rib structure. This increases the strength of the first arm base 121a.

[0025] As shown in Figure 1, the housing section 121b houses the second motor 151 of the second drive unit 15, which will be described later, and protrudes downward from the first arm base 121a. Therefore, when the first arm 12a is rotated relative to the base 11, the housing section 121b and the base 11 do not interfere with each other. As a result, the first arm 12a can be brought closer to the base 11 compared to the case where the housing section 121b protrudes upward from the first arm base 121a. In this specification, "the housing section 121b houses the second motor 151" means that most of the second motor 151 is housed in the housing section 121b, and a part of the second motor 151 is allowed to protrude upward from the housing section 121b. Also, the housing section 121b is spaced apart from the second arm 12b. Therefore, when the housing portion 121b protrudes downward from the first arm base 121a and the second arm 12b is rotated relative to the first arm 12a, a structure can be created in which the first arm 12a and the second arm 12b do not interfere with each other. However, the shape of the first arm 12a is not limited to the shape described above or shown in the figures.

[0026] 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 around the second axis A2. The second axis A2 is parallel to the first axis A1.

[0027] The second arm 12b extends along the second axis A2 and has a connecting portion 122a that is rotatably connected to the tip of the first arm 12a around the second axis A2, and a housing 122b that houses the third drive unit 16 and the fourth drive unit 17, which will be described later, and is equipped with a work head 13. The housing 122b includes a second arm base 123 connected to the lower end of the connecting portion 122a and extending in a direction perpendicular to the second axis A2, and a cover 124 positioned above the second arm base 123 and to the side of the connecting portion 122a, and detachably attached to the second arm base 123.

[0028] 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 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 first direction D1 and second direction D2 will also be referred to as "third direction D3." First direction D1 is also the direction parallel to the Z axis. Second direction D2 and 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."

[0029] The connecting portion 122a is hollow and, for example, cylindrical in shape. The length of the connecting portion 122a in the first direction D1 is set to such a length that the shaft 13c does not come into contact with the first arm 12a when the second arm 12b is rotated with the shaft 13c in its highest position. Therefore, in this embodiment, the second arm 12b can rotate 360 ​​degrees relative to the first arm 12a.

[0030] 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 first arm base 121a, and the lower end of the connecting portion 122a may be rotatably connected to the base end of the second arm base 123 around the second axis A2. Alternatively, the connecting portion 122a may have a first portion fixed to the first arm base 121a and extending along the first axis A1, and a second portion rotatably connected to the lower end of the first portion around the second axis A2, fixed to the second arm base 123, and extending along the first axis A1.

[0031] The second arm base 123 extends in the second direction D2. As shown in Figure 5, the second arm base 123 is hollow and, for example, has a rectangular parallelepiped shape with rounded corners. The side walls of the second arm base 123 have a rib structure. This increases the strength of the second arm base 123. However, the shape of the second arm base 123 is not limited to the shape described above and shown.

[0032] In this embodiment, the first arm base 121a and the second arm base 123 are manufactured by extrusion molding. Specifically, the first arm base 121a and the second arm base 123 are manufactured by extruding molded products using the same shape mold, and then processing them with through holes, recesses, etc., according to the equipment, linear members, etc. to be installed on each.

[0033] Therefore, the cross-sectional shape perpendicular to the longitudinal direction of the first arm base 121a is constant along the longitudinal direction of the first arm base 121a. Similarly, the cross-sectional shape perpendicular to the longitudinal direction of the second arm base 123 is constant along the longitudinal direction (second direction D2) of the second arm base 123. Hereafter, the cross-sectional shape perpendicular to the longitudinal direction of each arm base 121a and 123 will also be referred to as the "cross-sectional shape". As shown in Figures 4 and 5, the cross-sectional shape of the first arm base 121a and the cross-sectional shape of the second arm base 123 are the same.

[0034] Here, "cross-sectional shape" refers to the outer shape of the cross section, ignoring through holes, recesses, etc. Furthermore, "the same cross-sectional shape" includes not only cases where the two cross-sectional shapes are perfectly identical, but also cases where the two cross-sectional shapes are substantially the same to the extent that manufacturing tolerances are acceptable. Thus, in this embodiment, a common mold is used when manufacturing the first arm base 121a and the second arm base 123 by extrusion molding. This makes the manufacturing of the robot 10 easy and efficient, and also reduces manufacturing costs. In particular, as in this embodiment, when the first arm base 121a and the second arm base 123 have complex shapes such as rib structures for reinforcement, it is especially beneficial because there is no need to prepare two types of complex molds.

[0035] In this embodiment, the longitudinal length of the first arm base 121a and the longitudinal length of the second arm base 123 are the same. However, the longitudinal lengths of the first arm base 121a and the second arm base 123 may be made different by varying the extrusion lengths during extrusion molding. Furthermore, the manufacturing method of the first arm base 121a and the second arm base 123 is not limited to extrusion molding using a common mold. In addition, the first arm base 121a may have portions with different cross-sectional shapes along its longitudinal direction, and the second arm base 123 may have portions with different cross-sectional shapes along its longitudinal direction. Furthermore, all or part of the cross-sectional shape of the first arm base 121a may differ from the cross-sectional shape of the second arm base 123.

[0036] The housing 11a, first arm base 121a, housing section 121b, connecting section 122a, and second arm base 123 of the base 11 are each constructed of rigid bodies. In this specification, "rigid body" means that the deformation when a force is applied is negligibly small, that is, that is, a substantially rigid body. The constituent materials of the housing 11a, first arm base 121a, housing section 121b, connecting section 122a, and second arm base 123 of the base 11 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 that include two or more of these.

[0037] As mentioned above, when the first arm base 121a and the second arm base 123 are manufactured by extrusion molding, the constituent materials are not particularly limited, but it is preferable to use, for example, alloys containing aluminum, glass, carbon fiber, and composite materials thereof. Furthermore, the constituent materials of the housing section 121b and the cover 124 are not particularly limited, but it is preferable to use, for example, polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, thermoplastic resins such as acrylic resins, epoxy resins, thermosetting resins such as phenolic resins, etc.

[0038] As shown in Figure 1, the cover 124 is made of, for example, a plate material molded into a desired three-dimensional shape. The cover 124 is attached to the second arm base 123, thereby forming an internal space between the cover 124 and the second arm base 123.

[0039] As shown in Figure 6, the maximum length H1 of the cover 124 in the first direction D1 is greater than the maximum length H2 of the housing section 121b in the first direction D1. Therefore, the maximum length of the internal space of the cover 124 in the first direction D1 can be sufficiently secured while positioning the housing section 121b below the first arm base 121a. This allows internal components such as the third motor 161, transmission section 162, and fourth motor 171, which will be described later, to be housed inside the cover 124.

[0040] The units of H1 and H2 are the same. In this case, H2 / H1 is not particularly limited, but is preferably between 0.15 and 0.97, and more preferably between 0.3 and 0.9. This results in a better balance between H1 and H2, and as described above, sufficient storage space in the storage section 121b and internal space in the cover 124 can be secured.

[0041] Furthermore, as shown in Figure 1, the upper surface of 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, a solenoid valve, etc.

[0042] Viewed from the first direction D1, the housing portion 121b of the first arm 12a is positioned inside the rotational trajectory of the connector 124i when the second arm 12b is rotated. Therefore, the connector 124i provided on the upper surface of the cover 124 and the linear member connected to the connector 124i and exposed to the outside can be prevented from contacting the housing portion 121b when the second arm 12b is rotated relative to the first arm 12a. This allows the second arm 12b to rotate smoothly relative to the first arm 12a.

[0043] The cover 124 may be made of a rigid body, a flexible or elastic material that deforms slightly when force is applied, or 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 used for the housing 11a of the base 11.

[0044] The working head 13 is provided at the end (tip) of the second arm 12b on the second direction D2+ side. The working head 13 has a spline nut 13a and a ball screw nut 13b arranged coaxially 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.

[0045] 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.

[0046] An end effector 13d is attached to the lower end 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, suction head, etc.

[0047] The spline nut 13a is located at the bottom of the second arm base 123. The ball screw nut 13b is located above the spline nut 13a and extends from above the second arm base 123 into the interior of the second 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.

[0048] 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.

[0049] The tip of the second arm base 123 is provided with a through hole that penetrates the second arm base 123 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 passes through these through holes.

[0050] As the shaft 13c is lowered, the upper end of the shaft 13c and the upper stopper 131 are housed within the cover 124. The robot 10's control program limits the downward movement range of the shaft 13c so that it does not descend beyond a predetermined clearance above the upper stopper 131 from the pulley 162b of the third drive unit 16, which will be described later. As the shaft 13c is raised, the upper end of the shaft 13c and the upper stopper 131 are exposed outside the cover 124. The robot 10's control program limits the upward movement range of the shaft 13c so that it does not rise beyond a predetermined clearance below the lower stopper 132 shown in Figure 6 from the spline nut 13a. Hereinafter, the distance traveled by the shaft 13c in the first direction D1 from the highest position to the lowest position of the shaft 13c will also simply be referred to as the "maximum vertical stroke length S of the shaft 13c". In other words, the maximum vertical stroke length S 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. Since the upper end of the shaft 13c can be exposed to the outside of the cover 124, the maximum vertical stroke length S of the shaft 13c can be made longer compared to the case where the cover 124 always covers the upper end of the shaft 13c.

[0051] Furthermore, the lowest position of the shaft 13c may be when the upper stopper 131 contacts the upper surface of the pulley 162b of the third drive unit 16. Also, the highest position of the shaft 13c may be when the lower stopper 132 contacts 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 S of the shaft 13c. However, even in this case, the maximum possible stroke length S of the shaft 13c means the original possible length of the shaft 13c before the user imposed any restrictions.

[0052] Let H be the distance between the lower end of the shaft 13c and the support T1 when the shaft 13c is in its highest position. In other words, H corresponds to the minimum distance between the lower end of the shaft 13c and the support T1. The units of S and H are the same. In this case, H and S are not particularly limited, but it is preferable that H ≤ 3S, more preferably that H ≤ 2.7S, and even more preferably that 1.4S ≤ H ≤ 2.5S. This makes it less likely for the shaft 13c to interfere with objects such as workpieces or the floor located below the shaft 13c. In other words, the maximum vertical stroke length S of the shaft 13c can be fully utilized. As a result, the types and range of tasks that the robot 10 can perform can be broadened. 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 broadened.

[0053] As shown in Figure 1, the robot 10 further comprises a first drive unit 14, a second drive unit 15, a third drive unit 16, and a fourth drive unit 17.

[0054] The first drive unit 14 rotates the first arm 12a around the first axis A1 relative to the base 11. The first drive unit 14 includes a first motor 141, a belt drive 142, and a reduction gear 200. The first motor 141 generates power to rotate the first arm 12a relative to the base 11. The belt drive 142 transmits the power from the first motor 141 to the reduction gear 200. The reduction gear 200 reduces the rotation from the first motor 141 transmitted from the belt drive 142 and transmits the power from the first motor 141 to the first arm 12a. Thus, in this specification, "reducing the rotation from the first motor 141 and transmitting the power of the first motor 141 to the first arm 12a" means that other components such as a belt drive 142 may be interposed between the first motor 141 and the reduction gear 200, and other components such as the second support member 146 (described later) may be interposed between the reduction gear 200 and the first arm 12a. The same applies to the second drive unit 15 (described later). Further details of the configuration of the first drive unit 14 will be described later.

[0055] The second drive unit 15 rotates the second arm 12b around the second axis A2 relative to the first arm 12a. The second drive unit 15 includes a second motor 151, a belt drive 152, and a reduction gear 153. The second motor 151 generates power to rotate the second arm 12b relative to the first arm 12a. The belt drive 152 transmits the power from the second motor 151 to the reduction gear 153. The reduction gear 153 reduces the rotation from the second motor 151 transmitted from the belt drive 152 and transmits the power of the second motor 151 to the second arm 12b. The detailed configuration of the second drive unit 15 will be described later.

[0056] The third drive unit 16 moves the shaft 13c up and down along the third axis A3. The third drive unit 16 is housed within the housing 122b of the second arm 12b. The third drive unit 16 includes a third motor 161 that generates power to move the shaft 13c up and down, and a transmission unit 162 that transmits the power from the third motor 161 to the shaft 13c.

[0057] The third motor 161 is positioned on the second arm base 123. The third motor 161 is located between the connector 122a and the shaft 13c. The output shaft of the third motor 161 protrudes downward from the housing of the third motor 161.

[0058] The transmission unit 162 is located on the second arm base 123. In this embodiment, the transmission unit 162 is composed of a single-stage reduction belt drive. The transmission unit 162 includes a pulley 162a, a pulley 162b, and an endless belt 162c. The pulley 162a is fixed to the output shaft of the third motor 161. The pulley 162b is fixed to a ball screw nut 13b coaxially with the shaft 13c. The endless belt 162c is wrapped around the pulleys 162a and 162b.

[0059] The fourth drive unit 17 rotates the shaft 13c around the third axis A3. The fourth drive unit 17 is housed within the housing 122b of the second arm 12b. The fourth drive unit 17 includes a fourth motor 171 that generates power to rotate the shaft 13c, and a transmission unit 172 that reduces the rotation from the fourth motor 171 and transmits the power from the fourth motor 171 to the shaft 13c.

[0060] The fourth motor 171 is positioned on the second arm base 123. The fourth motor 171 is located between the connector 122a and the third motor 161. The output shaft of the fourth motor 171 protrudes downward from the housing of the fourth motor 171. However, the third motor 161 and the fourth motor 171 may be positioned side by side in the third direction D3. Also, the fourth motor 171 may be positioned between the third motor 161 and the shaft 13c.

[0061] The transmission unit 172 is housed within the second arm base 123. In this embodiment, the transmission unit 172 is composed of a two-stage reduction belt drive. The transmission unit 172 includes a pulley 172a, a pulley 172b, an endless belt 172c, a shaft member 172d, a pulley 172e, a pulley 172f, and an endless belt 172g. The pulley 172a is fixed to the output shaft of the fourth motor 171. The pulley 172b is located between the pulley 172a and the shaft 13c. The endless belt 172c is wrapped around the pulleys 172a and 172b. The pulley 172e is fixed coaxially to the pulley 172b. The pulley 172f is fixed coaxially to the shaft 13c and to the spline nut 13a. The endless belt 172g is wrapped around pulleys 172e and 172f. The shaft member 172d is provided with pulleys 172b and 172e. The shaft member 172d is rotatably supported by the second arm base 123.

[0062] However, the number of reduction stages in the transmission units 162 and 172 is not limited to the above. Furthermore, the transmission units 162 and 172 are not limited to belt drive systems, but may be composed of gear systems such as planetary gear systems or harmonic drive gear systems, or a combination of a belt drive system and a gear system.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] Next, the connection structure between the base 11 and the first arm 12a will be described in detail. As shown in Figure 2, the base plate portion 112 of the base 11 is provided with a first through hole 112h that extends along the first axis A1. Furthermore, a recessed portion 112d is provided on the outer periphery of the first through hole 112h on the upper surface of the base plate portion 112, which is recessed downwards. In plan view, the recessed portion 112d is annular with the first axis A1 as its center.

[0068] The first motor 141 of the first drive unit 14 is located inside the housing 11a. The first motor 141 is positioned away from the first shaft A1 in a direction perpendicular to the first shaft A1 (towards the Y-axis + side) and above the bottom plate portion 112 of the housing 11a. With the output shaft of the first motor 141 protruding downward from the housing of the first motor 141, the housing of the first motor 141 is fixed to the housing 11a via a support (not shown).

[0069] The belt drive device 142 of the first drive unit 14 is provided inside the housing 11a. The belt drive device 142 includes a first pulley 142a connected to the output shaft of the first motor 141, a second pulley 142b with the first shaft A1 as its center of rotation, and an endless belt 142c wrapped around the first pulley 142a and the second pulley 142b. The first pulley 142a and the second pulley 142b are located above the bottom plate portion 112. The second pulley 142b is provided with a radially extending screw hole 142h. The screw hole 142h communicates the external and internal spaces of the second pulley 142b. In this embodiment, the outer diameter of the first pulley 142a and the outer diameter of the second pulley 142b are approximately equal. However, the outer diameter of the first pulley 142a may be larger or smaller than the outer diameter of the second pulley 142b.

[0070] In this embodiment, the reduction gear 200 of the first drive unit 14 is configured as a harmonic drive gear. Compared to winding drive systems and the like, harmonic drive gears are compact and have a large reduction ratio. The reduction gear 200 has an input shaft 210 configured as a wave generator, an intermediate section 220 configured as a flex spline, an output shaft 230 configured as a circular spline, and a bearing 240. However, the reduction gear 200 may be configured as another gear system such as an eccentric oscillating gear system.

[0071] The reduction ratio of the reducer 200, i.e., the rotational speed of the input shaft 210 / the rotational speed of the output shaft 230, is not particularly limited, but in this embodiment, it is preferably 10 or more and 200 or less, and more preferably 50 or more and 150 or less.

[0072] The reduction gear 200 is housed within the housing 11a. In this specification, "the reduction gear 200 is housed within the housing 11a" means that the majority of the reduction gear 200 is located within the housing 11a, while allowing a portion of the reduction gear 200 to protrude outside the housing 11a. By housing the reduction gear 200 within the housing 11a, the separation distance G1 between the base 11 and the first arm 12a in the direction parallel to the first axis A1 can be shortened compared to the case where the entire reduction gear 200 is located outside the base 11. This makes it less likely for the lower end of the shaft 13c provided on the second arm 12b to interfere with objects such as workpieces or the floor located below the shaft 13c. Therefore, the maximum vertical stroke length S of the shaft 13c can be fully utilized.

[0073] The separation distance G1 between the base 11 and the first arm 12a, that is, the separation distance G1 between the bottom plate portion 112 and the first arm base 121a, is not particularly limited, but is preferably 2.0 mm or more and 4.0 mm or less, and more preferably 2.5 mm or more and 3.5 mm or less. This allows the first arm 12a to rotate smoothly relative to the base 11 while preventing the base 11 and the first arm 12a from separating too much.

[0074] Furthermore, a portion of the reduction gear 200 is positioned within the first through-hole 112h. This allows the reduction gear 200 to be positioned within the housing 11a of the base 11 while preventing it from being too far apart from the first arm 12a. As a result, the bending moment applied to the reduction gear 200 by rotating the first arm 12a is reduced, making it less likely for the input shaft 210, output shaft 230, and other parts of the reduction gear 200 to wobble. Consequently, wear on the parts of the reduction gear 200 is suppressed, extending the lifespan of the reduction gear 200. This also reduces power transmission loss from the reduction gear 200 to the first arm 12a.

[0075] Furthermore, the higher the reduction gear 200 is positioned, the higher the first motor 141 and the belt drive 142 need to be positioned. Consequently, the length of the housing 11a in the direction parallel to the first axis A1 increases. The base 11 of a ceiling-mounted robot 10 is often placed in the space above the ceiling where space is limited. Therefore, by placing the reduction gear 200 at the bottom of the housing 11a, as in this embodiment, it is possible to suppress the increase in the length of the housing 11a in the direction parallel to the first axis A1. This makes it possible to easily place the base 11 of a ceiling-mounted robot 10 in the space above the ceiling where space is limited.

[0076] Let L0 be the total length of the reducer 200 in the Z-axis direction, and L1 be the length in the Z-axis direction of the portion of the reducer 200 located below the lower surface of the bottom plate portion 112. The units of L0 and L1 are the same. In this case, L1 / L0 × 100 [%] is not particularly limited, but is preferably 0% or more and 10% or less, and more preferably 5% or more and 10% or less.

[0077] The input shaft 210 is positioned along the first shaft A1 and rotates around the first shaft A1 by power from the first motor 141 transmitted from the second pulley 142b. The input shaft 210 has a cylindrical body portion 211 and a bearing 212 in which the body portion 211 is positioned inside.

[0078] The main body 211 is made of a rigid body. The upper end of the main body 211 is located above the bottom plate 112, and the main body 211 passes through the first through hole 112h. Therefore, while the reduction gear 200 is installed inside the housing 11a, it is possible to prevent the reduction gear 200 and the first arm 12a from being separated too much. The lower end of the main body 211 is located below the bottom plate 112 and protrudes below the output shaft 230. As shown in Figure 3, the outer circumferential surface of the part of the main body 211 on which the bearing 212 is mounted is elliptical in plan view. Thus, because the main body 211 has an elliptical outer circumferential surface, it is also called an elliptical cam.

[0079] As shown in Figure 2, the upper end of the main body 211 is positioned inside the second pulley 142b. The set screw 142s is screwed into the threaded hole 142h of the second pulley 142b and pressed against the outer circumferential surface (side surface) of the main body 211. If the second pulley 142b were to be fixed to the main body 211 by a screw extending in a direction parallel to the first shaft A1, it would be necessary to provide a threaded hole in the main body 211 that extends in a direction parallel to the first shaft A1, and the radial thickness of the main body 211 would need to be increased accordingly. In contrast, in this embodiment, it is not necessary to provide a threaded hole in the input shaft 210, so the radial thickness of the input shaft 210 can be reduced. As a result, as will be described in detail later, the inner diameter of the sleeve 147, which is positioned inside the main body 211, can be increased. Consequently, the number of linear members passing inside the sleeve 147 can be increased. However, the method of fixing the second pulley 142b to the input shaft 210 is not limited to the method using the set screw 142s described above. For example, the second pulley 142b may be fixed to the input shaft 210 by a screw extending in a direction parallel to the first shaft A1.

[0080] The bearing 212 of the input shaft 210 is a deep groove ball bearing and has an inner ring 213, an outer ring 214, rolling elements 215, and a cage 216. However, the bearing 212 may be composed of other ball bearings such as angular contact ball bearings or other rolling bearings such as roller bearings. The bearing 212 is located slightly above the lower end of the main body 211. The bearing 212 is located within the first through hole 112h.

[0081] The inner ring 213 and outer ring 214 are flexible. The inner ring 213 is fixed to the outer circumferential surface of the main body 211 and rotates together with the main body 211 around the first axis A1. As shown in Figure 3, the inner ring 213 and outer ring 214 are elliptical in shape, following the shape of the elliptical portion of the main body 211.

[0082] As shown in Figure 2, the intermediate section 220 is constructed by a so-called top hat-shaped flex spline. The input shaft 210 is located inside the intermediate section 220. The intermediate section 220 has a flexible cylindrical section 221 that extends along the first axis A1, and an annular outer peripheral section 222 that is connected to the upper end of the cylindrical section 221 and extends radially outward from the cylindrical section 221.

[0083] The upper end of the cylindrical portion 221 is located above the bottom plate portion 112. An external gear 221a is provided at the lower end of the cylindrical portion 221. The external gear 221a is positioned within the first through hole 112h. The lower end of the external gear 221a is approximately flush with the lower surface of the bottom plate portion 112. As shown in Figure 3, the bearing 212 of the input shaft 210 is positioned inside the external gear 221a and is in contact with the outer ring 214 of the bearing 212. In other words, the external gear 221a and the outer ring 214 correspond to the "contact portion 210A" between the input shaft 210 and the intermediate portion 220. The contact portion 210A is located within the first through hole 112h.

[0084] The external gear 221a has a shape that follows the shape of the outer ring 214 of the input shaft 210. Therefore, the virtual curve C1 connecting the multiple tooth tips of the external gear 221a is elliptical in shape, following the shape of the outer ring 214 of the input shaft 210. When the main body 211 rotates, in a plan view, the positions of the major and minor axes of the outer surface of the main body 211 change around the first axis A1. Accordingly, the positions of the major and minor axes of the curve C1 also change around the first axis A1.

[0085] As shown in Figure 2, the bearing 240 fixes the intermediate portion 220 to the housing 11a and rotatably supports the output shaft 230. In this embodiment, the bearing 240 is composed of a cross-roller bearing and has an inner ring 241, an outer ring 242, and rolling elements 243. The cylindrical portion 221 of the intermediate portion 220 is located inside the bearing 240. The upper end of the inner ring 241, the upper end of the outer ring 242, and the rolling elements 243 of the bearing 240 are located above the bottom plate portion 112.

[0086] The inner ring 241 is separated from the intermediate portion 220. The lower end of the inner ring 241 is located within the first through hole 112h and is fixed to the output shaft 230.

[0087] The outer ring 242 corresponds to the "fixed part" that is fixed to the housing 11a in the reduction gear 200. The outer circumference 222 of the intermediate part 220 is fixed to the upper surface of the outer ring 242. The lower end of the outer ring 242 is positioned in the recess 112d of the bottom plate 112 and is fixed to the bottom plate 112 by screws or the like. Therefore, while the reduction gear 200 is installed in the housing 11a of the base 11, it is possible to prevent the reduction gear 200 and the first arm 12a from being too far apart. In addition, this prevents the rolling elements 243 from being too far apart from the first arm 12a. As a result, the bending moment applied to the part of the bearing 240 near the rolling elements 243 due to the rotation of the first arm 12a can be reduced. As a result, wear of the bearing 240 can be suppressed. This extends the life of the reduction gear 200. However, the recess 112d does not have to be provided in the bottom plate 112.

[0088] The output shaft 230 outputs a reduced rotation speed. That is, the output shaft 230 rotates at a rotation speed reduced from the rotation speed of the input shaft 210. The entire output shaft 230 is located within the first through hole 112h. Therefore, while the reduction gear 200 is provided within the housing 11a of the base 11, it is possible to prevent the reduction gear 200 and the first arm 12a from being too far apart. In this embodiment, the lower end of the output shaft 230 is flush with the lower surface of the bottom plate portion 112. However, the lower end of the output shaft 230 may be located above the lower surface of the bottom plate portion 112. Also, a part of the output shaft 230 may protrude upward or downward from the first through hole 112h.

[0089] The output shaft 230 is constructed of a rigid body. As shown in Figure 3, the output shaft 230 is constructed of an internal gear. The number of teeth on the output shaft 230 is greater than the number of teeth on the external gear 221a of the intermediate section 220. Also, the curve connecting the multiple tooth tips on the output shaft 230 is circular.

[0090] Therefore, some of the multiple teeth on the external gear 221a of the intermediate section 220 mesh with some of the multiple teeth on the output shaft 230. More specifically, of all the teeth on the external gear 221a, the teeth located near the long axis of the outer circumferential surface of the main body section 211 mesh with all the teeth on the output shaft 230, the teeth located near the long axis of the outer circumferential surface of the main body section 211. On the other hand, of all the teeth on the external gear 221a, the teeth located near the short axis of the outer circumferential surface of the main body section 211 mesh with all the teeth on the output shaft 230, the teeth located near the short axis of the outer circumferential surface of the main body section 211, and these teeth do not mesh with each other and are separated from each other.

[0091] As described above, when the main body 211 and the inner ring 213 of the bearing 212 rotate around the first axis A1, the positions of the major and minor axes of the curve C1 connecting the multiple tooth tips of the external gear 221a of the intermediate part 220 also change around the first axis A1 in a plan view. As a result, the meshing position between the external gear 221a and the output shaft 230 changes around the first axis A1 according to the position of the major axis of the outer circumferential surface of the main body 211. As described above, the number of teeth on the output shaft 230 is greater than the number of teeth on the intermediate part 220, so even if the input shaft 210 is rotated once, the output shaft 230 only rotates by an angle equivalent to the difference in the number of teeth between the intermediate part 220 and the output shaft 230. Therefore, the rotational speed of the output shaft 230 is slower than the rotational speed of the input shaft 210. In other words, the output shaft 230 can output a reduced rotation.

[0092] The contact portion 230A between the external gear 221a of the intermediate section 220 and the output shaft 230 is located within the first through hole 112h. Also, as mentioned above, the contact portion 210A between the input shaft 210 and the intermediate section 220 is also located within the first through hole 112h. Therefore, while the reduction gear 200 is installed within the housing 11a of the base 11, it is possible to prevent the power transmission portion of the reduction gear 200 from being too far away from the first arm 12a. This reduces the power transmission loss from the reduction gear 200 to the first arm 12a. Furthermore, since the Z-axis position (height) of the contact portions 210A and 230A is the same, the Z-axis length (height) of the reduction gear 200 can be made relatively small.

[0093] As shown in Figure 2, the first drive unit 14 further comprises a first bearing 144a, a second bearing 144b, a first support member 145, and a second support member 146.

[0094] The first bearing 144a rotatably supports the input shaft 210 and is located above the bottom plate portion 112. The inner ring of the first bearing 144a is fixed to the main body portion 211 of the input shaft 210, in a portion located above the bearing 240 and below the second pulley 142b.

[0095] The first support member 145 is annular in shape with the first shaft A1 at its center, and the first bearing 144a is positioned inside the first support member 145. The outer ring of the first bearing 144a is fixed to the first support member 145. In other words, the first support member 145 supports the first bearing 144a. The first support member 145 is fixed to the outer circumference 222 of the intermediate portion 220. In other words, the first support member 145 is fixed to the housing 11a via the intermediate portion 220 and the outer ring 242 of the bearing 240.

[0096] The second bearing 144b rotatably supports the input shaft 210 and is located below the bottom plate portion 112. The inner ring of the second bearing 144b is fixed to the portion of the main body portion 211 of the input shaft 210 that is located below the bottom plate portion 112. The first bearing 144a and the second bearing 144b can support both the portion of the input shaft 210 located above the bottom plate portion 112 and the portion of the input shaft 210 located below the bottom plate portion 112. Therefore, the axial runout of the input shaft 210 can be further suppressed. This further suppresses wear on the reduction gear 200 and extends the lifespan of the reduction gear 200.

[0097] The second support member 146 supports the second bearing 144b while connecting the output shaft 230 and the first arm 12a. The second support member 146 is annular in shape with the first shaft A1 at its center, and the second bearing 144b is positioned inside the second support member 146. The outer ring of the second bearing 144b is fixed to the second support member 146. In this way, the support of the second bearing 144b and the connection between the output shaft 230 and the first arm 12a can be performed by a single member, allowing the base 11 and the first arm 12a to be brought closer together. Furthermore, the number of parts can be reduced compared to the case where the support of the second bearing 144b and the connection between the output shaft 230 and the first arm 12a are performed by separate members. However, the support of the second bearing 144b and the connection between the output shaft 230 and the first arm 12a may also be performed by separate members.

[0098] A second through-hole 121h is provided in the upper wall of the first arm base 121a at a position opposite to the reduction gear 200. Furthermore, a recessed area 121d is provided on the outer periphery of the second through-hole 121h in the upper wall of the first arm base 121a. In plan view, the recessed area 121d is an annular shape centered on the first axis A1.

[0099] The second support member 146 has a first portion 146a that contacts the upper surface of the first arm base 121a, and a second portion 146b that protrudes downward from the inner circumference of the first portion 146a and is positioned within the second through hole 121h. The lower end of the output shaft 230 is fixed to the upper end of the first portion 146a. The lower end of the first portion 146a is positioned within the recess 121d and fixed to the first arm base 121a by screws or the like. In this way, by bringing the first portion 146a of the second support member 146 into contact with the upper surface of the first arm base 121a and fitting the second portion 146b into the second through hole 121h, displacement of the second support member 146 relative to the first arm 12a during rotation of the first arm 12a can be suppressed. However, the recess 121d is not required to be provided in the first arm base 121a.

[0100] A sleeve 147 is positioned inside the second pulley 142b, the input shaft 210, and the second portion 146b of the second support member 146. The sleeve 147 forms a passage for a linear member to pass through. The sleeve 147 is cylindrical and extends along the first shaft A1. The sleeve 147 is spaced apart from the second pulley 142b and the input shaft 210 and is fixed to the second portion 146b of the second support member 146. That is, the sleeve 147 rotates together with the output shaft 230, the second support member 146, and the first arm 12a.

[0101] The length in the Z-axis direction of the portion of the second support member 146 located above the upper end of the first arm base 121a is not particularly limited, but is preferably 2 mm or more and 8 mm or less, and more preferably 2.5 mm or more and 7.5 mm or less. By making the length in the Z-axis direction of the portion of the second support member 146 located above the upper end of the first arm base 121a greater than or equal to the lower limit value, the second bearing 144b can be placed inside the second support member 146. Furthermore, by making the length in the Z-axis direction of the portion of the second support member 146 located above the upper end of the first arm base 121a less than or equal to the upper limit value, it is possible to suppress an increase in the overall length of the second support member 146 in the Z-axis direction.

[0102] In this embodiment, the lower end of the output shaft 230 is flush with the lower surface of the bottom plate portion 112, but the lower end of the output shaft 230 may be located above the lower surface of the bottom plate portion 112. In this case, the distance in the Z-axis direction between the lower end of the output shaft 230 and the lower surface of the bottom plate portion 112 is preferably the length obtained by subtracting the preferred separation distance G1 between the bottom plate portion 112 and the first arm base 121a from the preferred Z-axis direction length of the portion of the second support member 146 located above the upper end of the first arm base 121a. The distance in the Z-axis direction between the lower end of the output shaft 230 and the lower surface of the bottom plate portion 112 is not particularly limited, but is preferably 0 mm or more and 6 mm or less, and more preferably 0 mm or more and 5 mm or less.

[0103] However, the positions and shapes of the input shaft 210, intermediate section 220, output shaft 230, and bearing 240 of the reduction gear 200 are not limited to those described above and shown in the illustration. For example, the cylindrical section 221 of the intermediate section 220 and the lower end of the output shaft 230 may protrude below the bottom plate section 112. Also, for example, the lower end of the input shaft 210 may be located above the lower surface of the bottom plate section 112. In this case, the lower end of the input shaft 210 does not need to be supported by the second bearing 144b.

[0104] Next, the second drive unit 15 will be described in detail. As shown in Figure 1, the belt drive device 152 of the second drive unit 15 includes a third pulley 152a connected to the output shaft of the second motor 151, a fourth pulley 152b with the second shaft A2 as its central axis, and an endless belt 152c wrapped around the third pulley 152a and the fourth pulley 152b.

[0105] The reduction gear 153 of the second drive unit 15 is composed of a harmonic drive gear. The input shaft of the reduction gear 153 is also fixed to the fourth pulley 152b using a set screw, similar to the input shaft 210 of the reduction gear 200 of the first drive unit 14, although this is not shown in the figure. This allows for a reduction in the radial wall thickness of the input shaft of the reduction gear 153 compared to the case where the fourth pulley 152b is fixed to the input shaft of the reduction gear 153 by a screw extending in a direction parallel to the second shaft A2. As a result, sufficient space can be secured inside the input shaft of the reduction gear 153 of the second drive unit 15 for inserting a linear member.

[0106] However, the reduction gear 153 may be composed of other gear devices such as an eccentric oscillating gear device, or a wrap-around transmission device such as a belt drive. Furthermore, the method of fixing the fourth pulley 152b to the input shaft of the reduction gear 153 is not limited to the method using the set screw described above. For example, the fourth pulley 152b may be fixed to the input shaft of the reduction gear 153 by a screw extending in a direction parallel to the second shaft A2.

[0107] As described above, the robot 10 according to this embodiment comprises a base 11, a first arm 12a, a second arm 12b, a shaft 13c, a first motor 141, a reduction gear 200, a second motor 151, and a third motor 161. The base 11 has a housing 11a. The first arm 12a is provided below the base 11 and is rotatable around a first axis A1 relative to the base 11. The second arm 12b is provided below 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 movable up and down along a third axis A3 parallel to the second axis A2. The first motor 141 is provided inside the housing 11a and generates power to rotate the first arm 12a relative to the base 11. The reduction gear 200 is located inside the housing 11a and reduces the rotation of the first motor 141, transmitting power to the first arm 12a. The second motor 151 generates power to rotate the second arm 12b relative to the first arm 12a. The third motor 161 generates power to raise and lower the shaft 13c. The housing 11a has a bottom plate portion 112 provided with a first through hole 112h extending along the first axis A1. Part of the reduction gear 200 is located within the first through hole 112h. The first arm 12a has a first arm base 121a extending in a direction perpendicular to the first axis A1, and a housing portion 121b that protrudes downward from the first arm base 121a, houses the second motor 151, and is separated from the second arm 12b.

[0108] By installing the reduction gear 200 inside the housing 11a of the base 11, the first arm 12a can be brought closer to the base 11 compared to the case where the entire reduction gear 200 is located outside the base 11. Also, since the housing section 121b that houses the second motor 151 protrudes downward from the first arm base 121a, the housing section 121b and the base 11 do not interfere with each other when the first arm 12a rotates. Therefore, the first arm 12a can be brought closer to the base 11 compared to the case where the housing section 121b protrudes upward from the first arm base 121a. As a result, the lower end of the shaft 13c provided on the second arm 12b is less likely to interfere with objects such as workpieces or the floor located below the shaft 13c. Therefore, the maximum vertical stroke length S of the shaft 13c can be fully utilized. As a result, the types and range of tasks that the robot 10 can perform can be expanded. Furthermore, it expands the range of choices for the end effector 13d that is attached to the shaft 13c and the workpiece that is the object being worked on.

[0109] Furthermore, a portion of the reduction gear 200 is positioned within the first through-hole 112h of the bottom plate 112. This allows the reduction gear 200 to be positioned within the housing 11a of the base 11 while preventing it from becoming too far apart from the first arm 12a. As a result, when the first arm 12a is rotated, the bending moment applied from the first arm 12a to the reduction gear 200 is reduced, making it less likely for the input shaft 210, output shaft 230, and other parts of the reduction gear 200 to wobble. Consequently, wear on the parts of the reduction gear 200 is suppressed, extending the lifespan of the reduction gear 200. This also reduces power transmission loss from the reduction gear 200 to the first arm 12a. Furthermore, this allows the reduction gear 200 to be positioned within the housing 11a while preventing the length of the housing 11a in the direction parallel to the first axis A1 from becoming excessive.

[0110] Furthermore, the reduction gear 200 has an input shaft 210 arranged along the first shaft A1 and rotated around the first shaft A1 by the power of the first motor 141, and an output shaft 230 arranged coaxially with the input shaft 210 and outputting reduced rotation. The output shaft 230 is located in the first through hole 112h. Therefore, while the reduction gear 200 is installed inside the housing 11a of the base 11, it is possible to prevent the reduction gear 200 and the first arm 12a from being separated too much. This allows for full utilization of the maximum vertical stroke length S of the shaft 13c, while extending the lifespan of the reduction gear 200.

[0111] Furthermore, the upper end of the input shaft 210 is located above the bottom plate portion 112, and the input shaft 210 passes through the first through hole 112h. Therefore, while the reduction gear 200 is installed inside the housing 11a of the base 11, it is possible to prevent the reduction gear 200 and the first arm 12a from being separated too much.

[0112] Furthermore, the lower end of the input shaft 210 is located below the base plate portion 112. The robot 10 further includes a first bearing 144a that rotatably supports the input shaft 210 and is located above the base plate portion 112, and a second bearing 144b that rotatably supports the input shaft 210 and is located below the base plate portion 112. Therefore, the axial runout of the input shaft 210 can be further suppressed. This further suppresses wear on various parts of the reducer 200, and extends the lifespan of the reducer 200.

[0113] Furthermore, the reduction gear 200 has an intermediate section 220 located between the input shaft 210 and the output shaft 230, which transmits the rotation of the input shaft 210 to the output shaft 230. The upper end of the intermediate section 220 is located above the bottom plate section 112. The contact portion 230A between the intermediate section 220 and the output shaft 230 is located within the first through hole 112h. Therefore, while the reduction gear 200 is installed inside the housing 11a of the base 11, it is possible to prevent the power transmission portion of the reduction gear 200 from being too far away from the first arm 12a. This reduces the power transmission loss from the reduction gear 200 to the first arm 12a.

[0114] Furthermore, the contact portion 210A between the input shaft 210 and the intermediate portion 220 is located within the first through hole 112h. Therefore, while the reduction gear 200 is installed within the housing 11a of the base 11, it is possible to prevent the power transmission portion of the reduction gear 200 from being too far away from the first arm 12a. This reduces the power transmission loss from the reduction gear 200 to the first arm 12a. In addition, since the contact portions 210A and 230A are at the same height, the height of the reduction gear 200 can be made relatively small.

[0115] Furthermore, the robot 10 is also equipped with a second support member 146 that connects the output shaft 230 and the first arm 12a while supporting the second bearing 144b. In this way, since the support of the second bearing 144b and the connection between the output shaft 230 and the first arm 12a can be performed by a single component, the first arm 12a can be brought closer to the base 11. Furthermore, the number of parts can be reduced compared to the case where the support of the second bearing 144b and the connection between the output shaft 230 and the first arm 12a are performed by separate components.

[0116] Furthermore, the first arm base 121a is provided with a second through-hole 121h at a position opposite to the reduction gear 200. The second support member 146 has a first portion 146a that contacts the upper surface of the first arm base 121a, and a second portion 146b that protrudes downward from the first portion 146a and is positioned within the second through-hole 121h. In this way, by bringing the first portion 146a of the support member into contact with the upper surface of the first arm base 121a and fitting the second portion 146b into the second through hole 121h, it is possible to suppress the displacement of the second support member 146 relative to the first arm 12a when the first arm 12a rotates.

[0117] Furthermore, the gearbox 200 has a fixed part (outer ring 242 of the bearing 240) that is fixed to the housing 11a. A recess 112d is provided on the outer circumference 222 of the first through hole 112h on the upper surface of the bottom plate portion 112, where the fixed part is located. Therefore, while the reduction gear 200 is installed inside the housing 11a of the base 11, it is possible to prevent the reduction gear 200 and the first arm 12a from being separated too much.

[0118] Furthermore, the second arm 12b extends in a direction perpendicular to the second axis A2 and includes a second arm base 123 on which the third motor 161 is installed, and a cover 124 that is detachably attached to the second arm base 123. The maximum length H1 of the cover 124 in the direction along the second axis A2 is greater than the maximum length H2 of the housing 121b in the direction along the second axis A2. Therefore, the housing section 121b can be positioned below the first arm base 121a while ensuring sufficient maximum length of the internal space of the cover 124 in the direction along the second axis A2.

[0119] Furthermore, a connector 124i is provided on the upper surface of the cover 124. When viewed from a direction parallel to the second axis A2, the housing portion 121b is positioned inward from the rotational trajectory of the connector 124i when the second arm 12b is rotated. Therefore, contact between the connector 124i provided on the upper surface of the cover 124 and the linear member connected to the connector 124i and the housing portion 121b can be suppressed. This allows the second arm 12b to rotate smoothly relative to the first arm 12a.

[0120] Furthermore, the cross-sectional shape perpendicular to the longitudinal direction of the first arm base 121a and the cross-sectional shape perpendicular to the longitudinal direction of the second arm base 123 are the same. In this way, by using parts with the same cross-sectional shape as components for the first arm base 121a and the second arm base 123, the robot 10 can be manufactured easily and efficiently. In particular, such parts with the same cross-sectional shape can be manufactured by extrusion molding using the same mold. Therefore, if the first arm base 121a and the second arm base 123 are manufactured using extrusion molding, the mold can be shared.

[0121] Furthermore, the input shaft 210 is cylindrical. The robot 10 further comprises a first pulley 142a, a second pulley 142b, an endless belt 142c, and a set screw 142s. The first pulley 142a is connected to the output shaft of the first motor 141. The second pulley 142b has a radially extending screw hole 142h, with the input shaft 210 of the reduction gear 200 positioned inside. The endless belt 142c is wrapped around the first pulley 142a and the second pulley 142b. The set screw 142s is positioned inside the screw hole 142h and is pressed against the input shaft 210 of the reduction gear 200. This allows the radial thickness of the input shaft 210 to be reduced compared to the case where the second pulley 142b is fixed to the input shaft 210 of the reduction gear 200 by a screw extending in the direction along the first shaft A1. This ensures sufficient space to insert a linear member inside the input shaft 210.

[0122] Furthermore, the base 11 is fixed to the support T1 located above the first arm 12a. Let S be the maximum vertical stroke length of the shaft 13c, and let H be the distance between the lower end of the shaft 13c and the support T1 when the shaft 13c is in its highest position. In this case, the relationship H ≤ 3S is satisfied. This makes it less likely for the shaft 13c to interfere with objects such as workpieces located below it. In other words, the maximum vertical stroke length S of the shaft 13c can be fully utilized.

[0123] 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]

[0124] 1...Robot system, 10...Robot, 11...Base, 11a...Housing, 11i...Connector, 12...Robot arm, 12a...First arm, 12b...Second arm, 13...Working head, 13a...Spline nut, 13b...Ball screw nut, 13c...Shaft, 13d...End effector, 14...First drive unit, 15...Second drive unit, 16...Third drive unit, 17...Fourth drive unit, 30...Control device, 111...Housing body, 111a...Top plate, 111b...Side wall, 112...Bottom plate, 112d...Recess, 112h...First through hole, 121a...First arm base 121b...Housing section, 121d...Recess, 121h...Second through hole, 122a...Connection section, 122b...Housing, 123...Second arm base, 124...Cover, 124i...Connector, 131...Upper stopper, 132...Lower stopper, 141...First motor, 142...Belt transmission device, 142a...First pulley, 142b...Second pulley, 142c...Endless belt, 142h...Screw hole, 142s...Set screw, 144a...First bearing, 144b...Second bearing, 145...First support member, 146...Second support member, 146a...First part, 146b...Second part ,147...Sleeve, 151...Second motor, 152...Belt transmission device, 152a...Third pulley, 152b...Fourth pulley, 152c...Endless belt, 153...Reduction gear, 161...Third motor, 162...Transmission section, 162a...Pulley, 162b...Pulley, 162c...Endless belt, 171...Fourth motor, 172...Transmission section, 172a...Pulley, 172b...Pulley, 172c...Endless belt, 172d...Shaft member, 172e...Pulley, 172f...Pulley, 172g...Endless belt, 200...Reduction gear, 210...Input shaft, 210A...Contact part, 211...Main body part, 212...Bearing, 213...Inner ring, 214...Outer ring, 215...Rolling element, 216...Cage, 220...Intermediate part, 221...Cylindrical part, 221a...External gear, 222...Outer circumference, 230...Output shaft, 230A...Contact part, 240...Bearing, 241...Inner ring, 242...Outer ring, 243...Rolling element, A1...First shaft, A2...Second shaft, A3...Third shaft, C1...Curve, D1...First direction, D2...Second direction, D3...Third direction, G1...Separation distance, H...Distance, H1...Maximum length, H2...Maximum length, L0...Total length, L1...Length, S...Maximum stroke length, T1...Support

Claims

1. A base having a housing, A first arm is provided below the base and is rotatable about a first axis relative to the base, A second arm is provided below 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 capable of moving up and down along a third axis parallel to the second axis, A first motor is provided within the housing and generates power to rotate the first arm relative to the base, A reduction gear is provided within the housing and reduces the rotation of the first motor and transmits the power to the first arm, A second motor generates power to rotate the second arm relative to the first arm, A third motor generates power to raise and lower the aforementioned shaft, Equipped with, The housing has a bottom plate portion provided with a first through hole extending along the first axis, A portion of the reduction gear is located within the first through-hole. The first arm has a first arm base extending in a direction perpendicular to the first axis, and a housing portion protruding downward from the first arm base, housing the second motor, and separated from the second arm. A robot characterized by the following features.

2. The reduction gear has an input shaft arranged along the first axis and rotating around the first axis by the power of the first motor, and an output shaft arranged coaxially with the input shaft and outputting reduced rotation, The robot according to claim 1, wherein the output shaft is located within the first through-hole.

3. The upper end of the input shaft is located above the bottom plate portion. The robot according to claim 2, wherein the input shaft passes through the first through hole.

4. The lower end of the input shaft is located below the bottom plate portion. The input shaft is rotatably supported by a first bearing located above the bottom plate portion, The input shaft is rotatably supported by a second bearing located below the bottom plate portion, The robot according to claim 3, further comprising:

5. The reduction gear further has an intermediate section located between the input shaft and the output shaft, which transmits the rotation of the input shaft to the output shaft. The upper end of the intermediate portion is located above the bottom plate portion. The robot according to claim 4, wherein the contact portion between the intermediate portion and the output shaft is located within the first through hole.

6. The robot according to claim 5, wherein the contact portion between the input shaft and the intermediate portion is located within the first through hole.

7. The robot according to any one of claims 4 to 6, further comprising a support member that connects the output shaft and the first arm while supporting the second bearing.

8. The first arm base is provided with a second through-hole at a position opposite to the reduction gear, The robot according to claim 7, wherein the support member has a first portion that contacts the upper surface of the first arm base and a second portion that protrudes downward from the first portion and is positioned within the second through hole.

9. The reduction gear has a fixing part that is fixed to the housing, The robot according to any one of claims 1 to 6, wherein a recess for which the fixing portion is arranged is provided on the outer periphery of the first through hole on the upper surface of the bottom plate portion.

10. The second arm extends in a direction perpendicular to the second axis and comprises a second arm base on which the third motor is installed, and a cover that is detachably attached to the second arm base. The robot according to any one of claims 1 to 6, wherein the maximum length of the cover in the direction along the second axis is greater than the maximum length of the housing in the direction along the second axis.

11. A connector is provided on the upper surface of the cover. The robot according to claim 10, wherein, when viewed from a direction parallel to the second axis, the housing is located inside the rotational trajectory of the connector when the second arm is rotated.

12. The robot according to claim 10, wherein the cross-sectional shape perpendicular to the longitudinal direction of the first arm base and the cross-sectional shape perpendicular to the longitudinal direction of the second arm base are the same.

13. The input shaft is cylindrical, A first pulley connected to the output shaft of the first motor, The input shaft of the reduction gear is positioned on the inside, and a second pulley is provided with a radially extending screw hole, An endless belt is wrapped around the first pulley and the second pulley, A set screw, which is placed in the screw hole and pressed against the input shaft of the reduction gear, The robot according to any one of claims 2 to 6, further comprising:

14. The base is fixed to a support located above the first arm, Let S be the maximum stroke length that the shaft can move up and down, and let H be the distance between the lower end of the shaft and the support when the shaft is in its highest position. H ≤ 3S A robot according to any one of claims 1 to 6 that satisfies the relationship.

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