Load compensation mechanism and load compensation device

Abstract

Provided is a load compensation mechanism having a wide movable area and excellent durability.　The load compensation mechanism comprises a base frame, an actuation arm, a crank, a first spring mechanism, and a second spring mechanism. The actuation arm has a connection part connected to the base frame so as to be rotatable around a rotation axis, and extends from the connection part in a plane perpendicular to the rotation axis. The crank is rotatable around the rotation axis together with the actuation arm, and extends in a direction different from that of the actuation arm in the plane perpendicular to the rotation axis. The first spring mechanism generates a first spring force with respect to the crank in accordance with a rotation angle around the rotation axis of the actuation arm in the plane perpendicular to the rotation axis. The second spring mechanism generates a second spring force with respect to the crank in accordance with the rotation angle around the rotation axis of the actuation arm in the plane perpendicular to the rotation axis. The first direction, which is a direction of the first spring force, is perpendicular to the second direction, which is a direction of the second spring force.

Description

Load compensation mechanism and load compensation device

[0001] The present disclosure relates to a load compensation mechanism and a load compensation device.

[0002] Japanese Patent Laid-Open Publication No. 2018-172193 (Patent Document 1) describes a load compensation mechanism that includes a base, a lower link member, an upper link member, a linear motion support member, a platform, first and second spring members, and first and second wires.

[0003] The base extends in the vertical direction. The lower link member has a first end and a second end. The lower link member is connected to the base at the first end so as to be rotatable about a first rotation axis. The upper link member has a third end and a fourth end. The upper link member is connected to the base between the third end and the fourth end so as to be rotatable about a second rotation axis. The upper link member is located above the lower link member.

[0004] The linear support member has a fifth end and a sixth end. The linear support member is connected to the second end at the fifth end so as to be rotatable about a third rotation axis, and is connected to the fourth end at the sixth end so as to be rotatable about a fourth rotation axis. The loading platform is connected to the linear support member so as to be movable along the extension direction of the linear support member.

[0005] One end of the first spring member is connected to the lower link member near the third rotation axis, and the other end of the first spring member is connected to one end of the first wire. The other end of the first wire is connected to the base between the lower link member and the upper link member. One end of the second spring member is connected to the upper link member at the third end, and the other end of the second spring member is connected to one end of the second wire near the second rotation axis. The other end of the second wire is connected to the upper link member near the fourth rotation axis. The position of the platform relative to the linear support member is fixed by a stopper so that the lower link member and the upper link member are horizontal. In the load compensation mechanism described in Patent Document 1, the weight of an object placed on the platform is compensated for by the link mechanism as described above.

[0006] Japanese Patent Application Laid-Open No. 2018-172193

[0007] However, the load compensation mechanism described in Patent Document 1 has a limited range of motion for the operating arm (lower link mechanism and upper link mechanism). Furthermore, the load compensation mechanism described in Patent Document 1 uses a wire, which raises concerns about wear and fatigue failure. The present disclosure has been made in consideration of the above-described problems with the conventional technology. More specifically, the present disclosure provides a load compensation mechanism that has a wide range of motion and excellent durability.

[0008] The load compensation mechanism of the present disclosure includes a base frame, an actuating arm, a crank, a first spring mechanism, and a second spring mechanism. The actuating arm has a connection portion connected to the base frame so as to be rotatable about a rotation axis, and extends from the connection portion in a plane perpendicular to the rotation axis. The crank is rotatable about the rotation axis together with the actuating arm, and extends in a different direction from the actuating arm in the plane perpendicular to the rotation axis. The first spring mechanism generates a first spring force on the crank in accordance with a rotation angle of the actuating arm about the rotation axis in the plane perpendicular to the rotation axis. The second spring mechanism generates a second spring force on the crank in accordance with a rotation angle of the actuating arm about the rotation axis in the plane perpendicular to the rotation axis. The first direction, which is the direction of the first spring force, is perpendicular to the second direction, which is the direction of the second spring force.

[0009] The load compensation mechanism of the present disclosure provides a wide range of motion and improves durability.

[0010] 1 is a front view of the load compensation mechanism 100. FIG. 2 is a side view of the load compensation mechanism 100. FIG. 3 is a plan view of the spring mechanism 40. FIG. 4 is an explanatory diagram of the operating mechanism of the spring mechanism 40. FIG. 5 is a first state diagram showing a state in which the actuating arm 20 is rotating. FIG. 6 is a second state diagram showing a state in which the actuating arm 20 is rotating. FIG. 7 is a third state diagram showing a state in which the actuating arm 20 is rotating. FIG. 8 is a fourth state diagram showing a state in which the actuating arm 20 is rotating. FIG. 9 is an explanatory diagram explaining a moment acting on the actuating arm 20. FIG. 10 is a first explanatory diagram explaining a moment acting on the crank 30. FIG. 11 is a second explanatory diagram showing a moment acting on the crank 30. FIG. 12 is a front view of the load compensation mechanism 200. FIG. 13 is a first schematic diagram of a load compensation device 300. FIG. 14 is a second schematic diagram of a load compensation device 300.

[0011] The details of the embodiments of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and redundant descriptions will not be repeated.

[0012] A load compensation mechanism according to embodiment 1 will be described. The load compensation mechanism according to embodiment 1 is designated as load compensation mechanism 100.

[0013] (Configuration of Load Compensation Mechanism 100) The configuration of the load compensation mechanism 100 will be described below.

[0014] Fig. 1 is a front view of the load compensation mechanism 100. Fig. 2 is a side view of the load compensation mechanism 100. As shown in Figs. 1 and 2, the load compensation mechanism 100 includes a base frame 10, an operating arm 20, a crank 30, a spring mechanism 40, a spring mechanism 50, and a positioning mechanism 60.

[0015] The base frame 10 is placed on, for example, a floor surface. A through hole is formed in the base frame 10. A shaft member 11 is inserted into the through hole of the base frame 10. The shaft member 11 is rotatable around its central axis.

[0016] The direction of the central axis of the shaft member 11 is the Z direction, and the central axis of the shaft member 11 is the Z axis. In a plane perpendicular to the Z axis, the central axis of the shaft member 11 is the origin, the direction perpendicular to the direction of gravity is the X direction, and the axis passing through the origin and parallel to the X direction is the X axis. Note that the direction from left to right in FIG. 2 is sometimes referred to as the +X direction, and the direction from right to left in FIG. 2 is sometimes referred to as the -Y direction. Also, in a plane perpendicular to the Z axis, the direction parallel to the direction of gravity (the direction perpendicular to the X direction) is the Y direction, and the axis passing through the origin and parallel to the Y direction is the Y axis. Note that the direction from bottom to top in FIG. 2 is sometimes referred to as the +Y direction, and the direction from top to bottom in FIG. 2 is sometimes referred to as the -Y direction.

[0017] The actuation arm 20 is connected to the base frame 10 so as to be rotatable about a rotation axis parallel to the Z direction. The portion where the actuation arm 20 is attached to the base frame 10 is referred to as the connection portion of the actuation arm 20. More specifically, the actuation arm 20 is connected to the shaft member 11 at the connection portion, and thereby connected to the base frame 10 so as to be rotatable about the Z axis. The actuation arm 20 extends linearly from the connection portion in a plane perpendicular to the Z axis (in the XY plane). The connection portion of the actuation arm 20 is located, for example, at the base end of the actuation arm 20 in the extension direction.

[0018] A workpiece W is attached near the tip of the operating arm 20 in the extension direction. In the XY plane, the distance from the base end of the operating arm 20 to the center of gravity of the operating arm 20, including the mass of the workpiece W, is defined as distance L. Note that gravity acting on the workpiece W and the operating arm 20 is along the -Y direction. In the XY plane, the angle formed between the +X direction and the extension direction of the operating arm 20 is defined as angle θ.

[0019] The crank 30 is connected to the shaft member 11 at the first connection portion. This allows the crank 30 to rotate around the Z axis together with the actuating arm 20. Furthermore, the crank 30 is connected to a frame 41 of a spring mechanism 40 (described later) at the second connection portion so as to be rotatable around a rotation axis parallel to the Z axis. The crank 30 extends linearly in the XY plane from the first connection portion to the second connection portion in a direction different from that of the actuating arm 20. The first and second connection portions of the crank 30 are located at the base end and tip end, respectively, in the extension direction of the crank 30.

[0020] In the XY plane, the distance between the first connecting portion of the crank 30 and the second connecting portion of the crank 30 is defined as distance R. The angle between the extension direction of the crank 30 and the +Y direction is defined as angle φ. The angle between the extension direction of the actuating arm 20 and the extension direction of the crank 30 in the XY plane is defined as angle ψ. In the example shown in Figures 1 and 2, the angle ψ is -90°.

[0021] The spring mechanism 40 has a frame 41, a frame 42, and a spring 43. The frame 41 is movable in the Y direction relative to the frame 42. The spring 43 is interposed between the frames 41 and 42. The spring 43 generates a spring force F along the Y direction depending on the position of the frame 41 relative to the frame 42. １ Generates.

[0022] 3A is a plan view of the spring mechanism 40. As shown in FIG. 3A , the frames 41 and 42 are, for example, U-shaped and T-shaped, respectively, in a plan view (when viewed along the Y direction). That is, the frames 41 and 42 have a nested structure. Therefore, the frame 41 can slide relative to the frame 42 in the Y direction without being interfered with by the frame 42. However, the structures of the frames 41 and 42 are not limited to this, and are not particularly limited as long as the frame 41 can slide relative to the frame 42 in the Y direction without being interfered with by the frame 42.

[0023] 3B is an explanatory diagram of the operation mechanism of the spring mechanism 40. When the frame 41 is displaced in the +Y direction relative to the frame 42 (when the frame 41 is above the frame 42), the spring force F １ is generated along the −Y direction, and when the frame 41 is displaced in the −Y direction relative to the frame 42 (when the frame 41 is below the frame 42), the spring force F １ When the position of the frame 41 and the position of the frame 42 are the same in the Y direction, the spring 43 has a natural length, and the spring force F １ is not assumed to occur.

[0024] 1 and 2, the spring mechanism 50 has frames 51 and 52, and a spring 53. The frame 51 is movable in the X direction relative to the frame 52. The configurations of the frames 51 and 52 are similar to those of the frames 41 and 42, respectively. The frame 51 is connected to the frame 42. The spring 53 is interposed between the frames 51 and 52. The spring 53 generates a spring force F along the X direction depending on the position of the frame 51 relative to the frame 52. ２ Generates.

[0025] More specifically, when the frame 51 is displaced in the +X direction relative to the frame 52 (when the frame 51 is to the right of the frame 52), the spring force F ２ occurs along the −X direction, and when the frame 51 is displaced in the −X direction relative to the frame 52 (when the frame 51 is to the left of the frame 52), the spring force F ２ When the position of the frame 51 and the position of the frame 52 are the same in the X direction, the spring 53 is at its natural length, and the spring force F ２ is not assumed to occur.

[0026] The positioning mechanism 60 moves the position of the frame 52 along the X direction. The positioning mechanism 60 is connected to the base frame 10. More specifically, the positioning mechanism 60 has, for example, a trapezoidal screw 61 and a handle 62. The trapezoidal screw 61 has a screw shaft 61a and a nut 61b. The screw shaft 61a extends along the X direction. The nut 61b is threadedly engaged with the screw shaft 61a and is connected to the frame 52. The handle 62 is connected to an end of the screw shaft 61a. By turning the handle 62, the screw shaft 61a rotates around its central axis, and the nut 61b moves along the X direction. Because the frame 52 is connected to the nut 61b, it moves along the X direction in accordance with the movement of the nut 61b along the X direction. In this manner, the position of the frame 52 in the X direction is adjusted.

[0027] (Effects of Load Compensation Mechanism 100) The effects of the load compensation mechanism 100 will be described below.

[0028] Fig. 4A is a first state diagram showing a state in which the actuation arm 20 is rotating. Fig. 4B is a second state diagram showing a state in which the actuation arm 20 is rotating. Fig. 4C is a third state diagram showing a state in which the actuation arm 20 is rotating. Fig. 4D is a fourth state diagram showing a state in which the actuation arm 20 is rotating. Figs. 4A to 4D respectively show cases in which the tip of the actuation arm 20 is in the first to fourth quadrants in the XY plane. As shown in Figs. 4A to 4D, the actuation arm 20 has no limit to its range of motion (i.e., the angle θ can be any angle).

[0029] 5A is an explanatory diagram illustrating a moment acting on the actuation arm 20. As shown in FIG. 5A, the actuation arm 20 has a T １ A moment of mgLcosθ acts on the actuator arm 20. Here, m is the weight of the actuator arm 20 including the workpiece W, and g is the gravitational acceleration. Note that the counterclockwise moment is positive.

[0030] 5B is a first explanatory diagram illustrating the moment acting on the crank 30. As shown in FIG. 5B, the compression amount ΔY of the spring 43 from its natural length is Rcosφ-α. Here, α is the initial compression amount of the spring 43, and is determined by the positioning mechanism 60. Therefore, if K is the spring constant, the spring force F in the spring mechanism 40 is １ =KΔY occurs, and this generates a moment T around the Z axis on the crank 30. ２ =KΔYRsinφ=KR ２ cosφ sinφ-KαR sinφ is generated.

[0031] 5C is a second explanatory diagram showing the moment acting on the crank 30. When viewed in relation to the spring mechanism 50, the phase of the crank 30 is shifted by 90° compared to when viewed in relation to the spring mechanism 40. Therefore, as shown in FIG. 5C, the compression amount ΔX of the spring 53 from its natural length is Rcos(φ+90°)-β. Here, β is the initial compression amount of the spring 53, and is determined by the positioning mechanism 60. Therefore, the spring force F in the spring mechanism 50 is ２ =KΔX occurs, which causes a moment T around the Z axis on the crank 30. ３ =KΔXR sin(φ+90°) =-KR2 cos φ sin φ+KβR cos φ is generated.

[0032] T ２ and T ３ T １ To balance with １ +T ２ +T ３ = 0, that is, -mgL cos θ - KR(α sin φ + β cos φ) = 0 must be satisfied. Because θ, φ, and ψ satisfy the relationship φ = θ + ψ, rearranging the above equation for moment balance using the addition theorem of trigonometric functions gives α sin ψ + β cos ψ + tan θ(α cos ψ - β sin ψ) = -mgL / (KR) (this equation will be referred to as Equation 1).

[0033] For Equation 1 to be satisfied regardless of the value of θ, αcosψ-βsinψ=0, i.e., α=βtanψ. Substituting α=βtanψ into Equation 1, we obtain βtanψsinψ+βcosψ=-mgL / (KR). Rearranging this equation yields β=-mgLcosψ / (KR) and α=-mgLsinψ / (KR) (these equations are referred to as Equation 2 and Equation 3, respectively). In this way, by appropriately determining α and β using the positioning mechanism 60, it is possible to cancel the weight of the operating arm 20 regardless of the angle θ. As described above, the weight of the operating arm 20 is canceled by the spring force of the springs (springs 43 and 53). Since structural components such as wires that are susceptible to wear and fatigue are not used, the load compensation mechanism 100 improves durability.

[0034] 1 and 2, that is, when ψ = -90°, Equations 2 and 3 become α = mgL / (KR) and β = 0, respectively. In this case, simply adjusting α with the positioning mechanism 60 can accommodate changes in the center of gravity of the operating arm 20 that occur due to changes in the workpiece W, etc. Furthermore, in this case, the value of α is proportional to the weight of the operating arm 20 (m and α have a linear relationship), so the above adjustment is intuitive and easy to understand.

[0035] A load compensation mechanism according to embodiment 2 will be described. The load compensation mechanism according to embodiment 2 is designated as load compensation mechanism 200.

[0036] (Configuration of Load Compensation Mechanism 200) The configuration of the load compensation mechanism 200 will be described below.

[0037] 6 is a front view of the load compensation mechanism 200. As shown in FIG. 6, the load compensation mechanism 200 includes a base frame 10, an operating arm 20, cranks 31 and 32, spring mechanisms 40 and 50, and a positioning mechanism 60.

[0038] In the load compensation mechanism 200, the operating arm 20 is hollow inside. In the load compensation mechanism 200, the shaft member 12 is connected to the base frame 10, and the base frame 10 is connected to the shaft member 12 so as to be rotatable around the central axis of the shaft member 12 (around the Z axis). In the load compensation mechanism 200, the shaft member 12 and the shaft member 13 are connected by a transmission member 14. The transmission member 14 is a chain, a timing belt, or the like. By being connected by the transmission member 14, the shaft member 12 and the shaft member 13 have a rotation ratio of 1:1. A work support table 15 may be connected to the shaft member 13.

[0039] The crank 31 and the crank 32 are supported by the shaft member 12 and the shaft member 13, respectively. The crank 31 rotates relative to the operating arm 20 as the operating arm 20 rotates. The crank 31 is located on the Y axis, for example. The phase of the crank 32 is always shifted by 90° from the phase of the crank 31.

[0040] In the load compensation mechanism 200, a linear motion mechanism 21 is disposed inside the actuation arm 20. The linear motion mechanism 21 has, for example, a rail 21 a and a slide block 21 b. The rail 21 a extends along the extension direction of the actuation arm 20. The slide block 21 b is attached to the rail 21 a so as to be movable relative to the actuation arm 20 along the extension direction of the actuation arm 20.

[0041] In the load compensation mechanism 200, the spring mechanism 40 is stored inside the actuation arm 20. In the load compensation mechanism 200, the spring mechanism 40 has frames 44 and 45, and a spring 46. The frame 44 is connected to the linear motion mechanism 21 and is movable along the extension direction of the actuation arm 20. A slit 44a is formed in the frame 44. The extension direction of the slit 44a is perpendicular to the extension direction of the actuation arm 20. A tip of the crank 31 is inserted into the slit 44a to form a cam follower, and the frame 44 moves in accordance with the rotation of the actuation arm 20.

[0042] The frame 45 is connected to the actuating arm 20 via a positioning mechanism 60, and the position of the frame 45 in the extension direction of the actuating arm 20 is adjusted by the positioning mechanism 60. The spring 46 is interposed between the frame 44 and the frame 45. As the actuating arm 20 rotates, the frame 44 moves in the extension direction of the actuating arm 20, and the spring 46 is compressed in the extension direction of the actuating arm 20, so that the spring mechanism 40 generates a spring force according to the rotation state of the actuating arm 20.

[0043] In the load compensation mechanism 200, the spring mechanism 50 is stored inside the operating arm 20. In the load compensation mechanism 200, the spring mechanism 50 has frames 54 and 55, and a spring 56. The frame 54 is connected to the linear motion mechanism 21 and is movable along the extension direction of the operating arm 20. A slit 54a is formed in the frame 54. The extension direction of the slit 54a is perpendicular to the extension direction of the operating arm 20. A cam follower is formed by inserting the tip of the crank 32 into the slit 54a, and the frame 54 moves in accordance with the rotation of the operating arm 20.

[0044] The frame 55 is connected to the actuating arm 20. The spring 56 is interposed between the frames 54 and 55. As the actuating arm 20 rotates, the frame 54 moves in the extension direction of the actuating arm 20, and the spring 56 is compressed in the extension direction of the actuating arm 20, so that the spring mechanism 50 generates a spring force according to the rotation state of the actuating arm 20. As described above, the phase of the crank 32 is shifted by 90° from the phase of the crank 31, and therefore the phase of the spring force generated by the spring mechanism 50 is shifted by 90° from the phase of the spring force generated by the spring mechanism 40.

[0045] (Effects of Load Compensation Mechanism 200) The effects of the load compensation mechanism 200 will be described below.

[0046] In the load compensation mechanism 200, similar to the load compensation mechanism 100, the spring forces of different phases generated by the spring mechanisms 40 and 50 cancel the moment due to the weight of the actuating arm 20 regardless of the rotation angle of the actuating arm 20, and it is possible to rotate the actuating arm 20 without limiting the rotation angle. Note that in the load compensation mechanism 200, it is not necessary to match the spring constants of the springs 46 and 56; it is sufficient to appropriately adjust the radii of the cranks 31 and 32 in accordance with the spring constants of the springs 46 and 56.

[0047] Furthermore, in the load compensation mechanism 200, by arranging the crank 31 on the Y-axis, it is possible to adjust the compensation load using a single positioning mechanism (positioning mechanism 60) without providing a positioning mechanism for the spring mechanism 50. Note that, because the shaft member 13 does not rotate relative to the base frame 10 and maintains the same angle, a pseudo-parallel link is formed in the load compensation mechanism 200. Therefore, when the work support table 15 is connected to the shaft member 13 and a workpiece W is mounted on the work support table 15, the workpiece W can be supported while maintaining its angle relative to the base frame 10, and the compensation load can be adjusted even when the workpiece W is mounted on the work support table 15 without considering the position of the center of gravity.

[0048] A load compensation device according to embodiment 3 will be described. The load compensation device according to embodiment 3 is designated as load compensation device 300.

[0049] Fig. 7A is a first schematic diagram of the load compensation device 300. Fig. 7B is a second schematic diagram of the load compensation device 300. As shown in Fig. 7A and Fig. 7B, the load compensation device 300 has a load compensation mechanism 100. In the load compensation device 300, a load compensation mechanism 200 may be used instead of the load compensation mechanism 100.

[0050] The load compensation device 300 forms a multi-joint arm (two joints in the example in FIG. 7A ). In the load compensation device 300, two load compensation mechanisms 100 are used for the first joint. One of the two load compensation mechanisms 100 is used for load compensation of the first joint, and the other of the two load compensation mechanisms 100 is connected to the second joint via a transmission member 310 and used for load compensation of the second joint. In the load compensation device 300, a driven shaft 320 is connected to the first joint, causing the first joint to rotate around the rotation axis of the driven shaft 320. The load compensation device 300 is not limited to this example. For example, as shown in FIG. 7B , by appropriately adjusting the number of load compensation mechanisms 100 and the number of driven shafts 320, it is possible to realize a load compensation device 300 with various uses and ranges of motion.

[0051] [Appendix] Various aspects of the present disclosure are summarized as appendices.

[0052] <Supplementary Note 1> A load compensation mechanism comprising: a base frame; an actuating arm; a crank; a first spring mechanism; and a second spring mechanism, wherein the actuating arm has a connection part connected to the base frame to be rotatable about a rotation axis and extends from the connection part in a plane perpendicular to the rotation axis, the crank is rotatable about the rotation axis together with the actuating arm and extends in a different direction from the actuating arm in the plane perpendicular to the rotation axis, the first spring mechanism generates a first spring force on the crank in accordance with a rotation angle of the actuating arm about the rotation axis in the plane perpendicular to the rotation axis, and the second spring mechanism generates a second spring force on the crank in accordance with the rotation angle of the actuating arm about the rotation axis in the plane perpendicular to the rotation axis, and a first direction that is a direction of the first spring force is perpendicular to a second direction that is a direction of the second spring force.

[0053] <Supplementary Note 2> The load compensation mechanism according to Supplementary Note 1, further comprising a positioning mechanism, wherein at least one of the first spring mechanism and the second spring mechanism is connected to the crank, and the positioning mechanism is configured to be able to adjust the position at which the spring of the other of the first spring mechanism and the second spring mechanism is at its natural length.

[0054] <Supplementary Note 3> The load compensation mechanism according to Supplementary Note 2, wherein the first spring mechanism has a first frame and a second frame, and a first spring; the second spring mechanism has a third frame and a fourth frame, and a second spring; the first frame is connected to the crank and is movable relative to the second frame along the first direction; the first spring generates the first spring force according to a position of the first frame relative to the second frame; the third frame is connected to the second frame and is movable relative to the fourth frame along the second direction; the second spring generates the second spring force according to a position of the third frame relative to the fourth frame; and the positioning mechanism moves the fourth frame along the second direction to adjust a position at which the second spring has a natural length.

[0055] <Supplementary Note 4> The load compensation mechanism according to any one of Supplementary Note 1 to Supplementary Note 3, wherein, in a plane perpendicular to the rotation axis, the extension direction of the actuating arm is perpendicular to the extension direction of the crank.

[0056] <Supplementary Note 5> A robot includes a base frame, an actuating arm, a first spring mechanism and a second spring mechanism, a first crank and a second crank, and a positioning mechanism, wherein the actuating arm has a connection part connected to the base frame rotatably about a rotation axis and extends from the connection part in a plane perpendicular to the rotation axis, the first spring mechanism and the second spring mechanism are stored inside the actuating arm, the first spring mechanism has first and second frames and a first spring, the second spring mechanism has third and fourth frames and a second spring, the first frame is movable relative to the second frame in the extension direction of the actuating arm, the first crank is connected to the first frame movably in a direction perpendicular to the movement direction of the first frame, and the first spring generates a first spring force on the first crank according to the relative position of the first frame to the second frame, The positioning mechanism adjusts the position at which the first spring is at its natural length by moving the second frame along the extension direction of the actuating arm, the third frame is movable relative to the fourth frame in the extension direction of the actuating arm, the second crank is connected to the second frame so as to be movable in a direction perpendicular to the movement direction of the third frame, the phase of the second crank is shifted by 90° from the phase of the first crank, and the second spring generates a second spring force on the second crank according to the relative position of the third frame to the fourth frame, a load compensation mechanism.

[0057] <Supplementary Note 6> A load compensation device comprising: at least one of the load compensation mechanisms according to any one of Supplementary Note 1 to Supplementary Note 5; and a driven shaft, wherein the actuating arm has a tip end in an extension direction of the actuating arm, and the tip end is moved by transmission of rotation of the driven shaft to the load compensation mechanism.

[0058] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of this application is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0059] 10 base frame, 11 shaft member, 12, 13 shaft member, 14 transmission member, 15 work support table, 20 operating arm, 21 linear motion mechanism, 21a rail, 21b slide block, 30, 31, 32 crank, 40 spring mechanism, 41, 42 frame, 43 spring, 44 frame, 44a slit, 45 frame, 46 spring, 50 spring mechanism, 51, 52, 53 spring, 54 frame, 54a slit, 55 frame, 56 spring, 60 positioning mechanism, 61 trapezoidal screw, 61a screw shaft, 61b nut, 62 handle, 100, 200 load compensation mechanism, 300 load compensation device, 310 transmission member, 320 driven shaft, L, R distance, W work.

Claims

1. A load compensation mechanism comprising: a base frame; an actuating arm; a crank; a first spring mechanism; and a second spring mechanism, wherein the actuating arm has a connection part connected to the base frame so as to be rotatable about a rotation axis and extends from the connection part in a plane perpendicular to the rotation axis, the crank is rotatable about the rotation axis together with the actuating arm and extends in a different direction from the actuating arm in the plane perpendicular to the rotation axis, the first spring mechanism generates a first spring force on the crank in accordance with the rotation angle of the actuating arm about the rotation axis in the plane perpendicular to the rotation axis, and the second spring mechanism generates a second spring force on the crank in accordance with the rotation angle of the actuating arm about the rotation axis in the plane perpendicular to the rotation axis, and a first direction which is the direction of the first spring force is perpendicular to a second direction which is the direction of the second spring force.

2. A load compensation mechanism as described in claim 1, further comprising a positioning mechanism, one of the first spring mechanism and the second spring mechanism being connected to the crank, and the positioning mechanism being configured to be able to adjust the position at which the spring of the other of the first spring mechanism and the second spring mechanism is at its natural length.

3. The load compensation mechanism according to claim 2, wherein the first spring mechanism has a first frame and a second frame, and a first spring; the second spring mechanism has a third frame and a fourth frame, and a second spring; the first frame is connected to the crank and is movable relative to the second frame along the first direction; the first spring generates the first spring force according to the relative position of the first frame to the second frame; the third frame is connected to the second frame and is movable relative to the fourth frame along the second direction; the second spring generates the second spring force according to the relative position of the third frame to the fourth frame; and the positioning mechanism adjusts the position at which the second spring is at its natural length by moving the fourth frame along the second direction.

4. A load compensation mechanism as claimed in any one of claims 1 to 3, wherein, in a plane perpendicular to the rotation axis, the extension direction of the operating arm is perpendicular to the extension direction of the crank.

5. A device comprising: a base frame; an operating arm; first and second spring mechanisms; a first and second crank; and a positioning mechanism, wherein the operating arm has a connection part connected to the base frame so as to be rotatable around a rotation axis, and extends from the connection part in a plane perpendicular to the rotation axis, the first and second spring mechanisms being stored inside the operating arm, the first spring mechanism having first and second frames and a first spring, the second spring mechanism having third and fourth frames and a second spring, the first frame being movable relative to the second frame in the extension direction of the operating arm, the first crank being connected to the first frame so as to be movable in a direction perpendicular to the movement direction of the first frame, and the first spring generating a first spring force on the first crank according to the relative position of the first frame to the second frame, A load compensation mechanism in which the positioning mechanism adjusts the position at which the first spring is at its natural length by moving the second frame along the extension direction of the actuating arm, the third frame is movable relative to the fourth frame in the extension direction of the actuating arm, the second crank is connected to the second frame so as to be movable in a direction perpendicular to the movement direction of the third frame, the phase of the second crank is shifted by 90° from the phase of the first crank, and the second spring generates a second spring force on the second crank according to the relative position of the third frame to the fourth frame.

6. A load compensation device comprising at least one of the load compensation mechanisms described in any one of claims 1 to 5 and a driven shaft, wherein the operating arm has a tip end in the extension direction of the operating arm, and the tip end is moved by the rotation of the driven shaft being transmitted to the load compensation mechanism.

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