direct-acting mechanism

Abstract

This application provides a direct-acting mechanism, the purpose of which is to improve rigidity while suppressing the enlargement of the mechanism in a direct-acting mechanism applicable to robotic arms and the like. The direct-acting mechanism (1) of this embodiment has: a plurality of direct-acting elements (11, 13, 15, 17) connected in series in a manner that allows them to move freely with each other; a shaft (41) fixed to one of the adjacent direct-acting elements (11, 13, 15, 17); and a sliding member (42) engaged with the shaft (41) in a manner that allows it to move freely and fixed to the other of the adjacent direct-acting elements.

Description

Technical Field

[0001] This application relates to a direct-acting mechanism. Background Technology

[0002] In robotic devices, highly flexible, extendable arms are sometimes used. These extendable arms are constructed from multiple nested cylindrical components of varying diameters. They require small size, lightweight design, high rigidity, and dust and drip resistance.

[0003] In telescopic booms where cylindrical components move relative to each other, a gap is required in the sliding parts to reduce sliding resistance during extension and retraction. This gap is essential for ensuring smooth sliding; however, it reduces the overall rigidity of the boom. Furthermore, telescopic booms typically have multiple segments of linear guides covered by a housing. In this structure, to improve rigidity, the linear guides need to be thicker, and to match this, the outer diameter of the housing also increases, resulting in an overall increase in boom size and weight. Summary of the Invention

[0004] The problem the invention aims to solve

[0005] In direct-acting mechanisms applicable to robotic arms, it is desirable to increase rigidity while suppressing the increase in the size of the mechanism.

[0006] means for solving problems

[0007] One aspect of the direct-acting mechanism disclosed herein includes: a plurality of direct-acting elements connected in series in a manner that allows them to move freely relative to each other; a shaft fixed to one of the adjacent direct-acting elements; and a slider engaged with the shaft in a manner that allows it to move freely, and fixed to the other of the adjacent direct-acting elements.

[0008] Another aspect of the direct-acting mechanism disclosed herein includes: a plurality of cylindrical bodies that move freely relative to each other and are arranged in a multi-level nested structure; a plurality of shafts housed inside the cylindrical bodies; and a plurality of sliding members that engage with the plurality of shafts in a freely movable manner; the shafts are fixed to one side of an adjacent cylindrical body among the plurality of cylindrical bodies, the sliding members are fixed to the other side of the adjacent cylindrical body, the plurality of cylindrical bodies move freely in the horizontal direction via the plurality of shafts and the plurality of sliding members, and the plurality of shafts are concentrated in the upper half of the cylindrical body, offset from the cylindrical centerline of the cylindrical body.

[0009] The effects of the invention

[0010] Based on this design, rigidity can be improved while suppressing the increase in the size of the mechanism in direct-acting mechanisms such as robotic arms. Attached Figure Description

[0011] Figure 1 This is a perspective view of the direct-acting mechanism during contraction in one embodiment.

[0012] Figure 2 It is a three-dimensional diagram of the linear motion mechanism during extension.

[0013] Figure 3 yes Figure 2 The front view of the direct-acting mechanism.

[0014] Figure 4 yes Figure 3 AA' cross-sectional view.

[0015] Figure 5 It is shown Figure 4 A diagram showing the state of the direct-acting mechanism during contraction.

[0016] Figure 6 yes Figure 3 BB' cross-sectional view.

[0017] Figure 7 It is shown Figure 6 A diagram showing the state of the direct-acting mechanism during contraction.

[0018] Figure 8 yes Figure 3 CC' cross-sectional view.

[0019] Figure 9 It is shown Figure 8 A diagram showing the state of the direct-acting mechanism during contraction.

[0020] Figure 10 It is shown Figure 1 A three-dimensional diagram of a deformed example of an arm structure.

[0021] Figure 11 It is shown Figure 10 A three-dimensional view of the extension of the direct-acting mechanism.

[0022] Figure 12 yes Figure 11 The front view of the direct-acting mechanism.

[0023] Figure 13 yes Figure 12 DD' cross-sectional view.

[0024] Figure 14 It is shown Figure 13 A diagram showing the state of the direct-acting mechanism during contraction.

[0025] Figure 15 yes Figure 12 E-E' cross-section.

[0026] Figure 16It is shown Figure 15 A diagram showing the state of the direct-acting mechanism during contraction.

[0027] Figure 17 yes Figure 12 FF' cross-sectional view.

[0028] Figure 18 It is shown Figure 17 A diagram showing the state of the direct-acting mechanism during contraction. Detailed Implementation

[0029] The direct-acting mechanism of this embodiment will now be described with reference to the accompanying drawings. In the following description, constituent elements having substantially the same function and structure will be given the same reference numerals, and will be described repeatedly only where necessary. The direct-acting mechanism of this embodiment can be used independently or as the arm (movable part) of a direct-acting telescopic joint of a robotic arm mechanism.

[0030] like Figure 1 , Figure 2 As shown, the direct-acting mechanism 1 has a plate-shaped base 90 and an arm 10 supported by the base 90 and capable of free extension and retraction. The arm 10 is composed of multiple direct-acting elements connected in series in a manner that allows them to move freely relative to each other. In this embodiment, a cylindrical body is used as an example of a direct-acting element. The arm 10 is composed of multiple cylindrical bodies that rigidly form a retractable structure (multi-level nested structure), and here, it is composed of four cylindrical bodies 11, 13, 15, and 17. In addition, the cylindrical body constituting the arm 10 may also be in the shape of a square tube.

[0031] like Figures 4 to 9 As shown, at the base 90, the last cylindrical body 11 is fixed to the rear flange of the base 90. The cylindrical body 13 is connected to the last cylindrical body 11 in a freely movable manner via a sliding bearing 21 located on the inner circumferential surface of the front end of the last cylindrical body 11. The cylindrical body 15 is connected to the cylindrical body 13 in a freely movable manner via a sliding bearing 23 located on the inner circumferential surface of the front end of the cylindrical body 13. The foremost cylindrical body 17 is connected to the cylindrical body 15 via a sliding bearing 25 located on the inner circumferential surface of the front end of the cylindrical body 15. By employing a structure that connects two adjacent cylindrical bodies via sliding bearings, the overall thickening of the arm 10 is prevented, and the waterproof and dustproof functions of the arm 10 are improved.

[0032] The arm 10 constituting the above-described telescopic structure can extend and retract along the centerline CL1 of the cylinder. Because of the telescopic structure, the arm 10 itself possesses a certain degree of rigidity. However, for example, in cases requiring a long extension length or in robotic arm mechanisms used for picking up heavy objects, it is necessary to further improve the rigidity of the arm 10. In this embodiment, a reinforcing structure is provided to further improve the rigidity of the arm 10 constituting the telescopic structure. Typically, the reinforcing structure is constituted by a ball spline mechanism. The ball spline mechanism is located between two adjacent cylinders. Furthermore, in this embodiment, from the viewpoint of ensuring rigidity, a ball spline mechanism is used as the reinforcing structure, but other direct-acting mechanisms, such as a direct-acting mechanism consisting of a guide rail and a sliding member engaging with the guide rail, may also be used.

[0033] Specifically, such as Figure 4 As shown, the first spline shaft 41, constituting the first ball spline mechanism, is fixed at its rear end to the base 90 with an orientation parallel to the cylinder centerline CL1. The first spline nut 42, inserted into the first spline shaft 41, is fixed to the first connecting plate 33, which is connected to the rear end edge of the cylinder 13. Thus, the first spline nut 42 moves with the movement of the cylinder 13 relative to the cylinder 11, thereby being able to move relative to the first spline shaft 41.

[0034] like Figure 6 As shown, the second spline shaft 43, constituting the second ball spline mechanism, is fixed at its rear end to the first connecting plate 33 with an orientation parallel to the cylinder centerline CL1. The second spline nut 44, inserted into the second spline shaft 43, is fixed to the second connecting plate 35, which is connected to the rear end edge of the cylinder 15. Thus, the second spline nut 44 moves with the cylinder 15 relative to the cylinder 13, thereby being able to move relative to the second spline shaft 43.

[0035] like Figure 8 As shown, the third spline shaft 45, constituting the third ball spline mechanism, is fixed at its rear end to the second connecting plate 35 with an orientation parallel to the cylinder centerline CL1. The third spline nut 46, inserted into the third spline shaft 45, is fixed to the third connecting plate 37, which is connected to the rear end edge of the cylinder 17. Thus, the third spline nut 46 moves with the cylinder 17 relative to the cylinder 15, thereby being able to move relative to the third spline shaft 45.

[0036] like Figure 5 , Figure 7 , Figure 9 As shown, when the arm 10 has been retracted, in order to prevent the first ball spline mechanism from colliding with the second connecting plate 35 and the third connecting plate 37, as follows: Figure 4As shown, openings 351 and 371 are respectively provided on the second connecting plate 35 and the third connecting plate 37. Openings 351 and 371 are respectively located on the center line of the first spline shaft 41 and are respectively sized to allow the first ball spline mechanism to pass through. When the arm 10 has been retracted, in order to prevent the second ball spline mechanism from colliding with the third connecting plate 37, as shown... Figure 6 As shown, other openings 372 are provided on the third connecting plate 37. The other openings 372 are located on the center line of the second spline shaft 43 and are sized to allow the second ball spline mechanism to pass through.

[0037] In addition, such as Figure 5 As shown, the first spline shaft 41, the second spline shaft 43, and the third spline shaft 45 are preferably arranged at a position offset from the cylinder centerline CL1. This allows the drive mechanism for realizing the extension and retraction of the arm 10 to be housed within a free space, thus preventing the arm 10 from becoming too large. As the drive mechanism for the arm 10, any mechanism such as a block-type feed / retract mechanism, a rack and pinion mechanism, or a ball screw mechanism can be used.

[0038] In addition, such as Figure 4 , Figure 6 , Figure 8 As shown, the diameter R1 of the first spline shaft 41, preferably fixed to the base 90 on the root side of the arm 10, is larger than the diameters R2 and R3 of the second spline shaft 43 and the third spline shaft 45. Making the first spline shaft 41, which applies the greatest load to the base side of the arm 10, thicker helps to improve the rigidity of the root of the arm 10. Similarly, the diameter R3 of the third spline shaft 45 on the front side of the arm 10 is preferably smaller than the diameters R1 and R2 of the first spline shaft 41 and the second spline shaft 43. Making the third spline shaft 45, which applies the least load to the front side of the arm 10, thinner helps to reduce the weight of the linear motion mechanism.

[0039] According to the linear motion mechanism 1 described above, the load applied to the arm 10 can be distributed to both the multiple cylindrical bodies 11, 13, 15, and 17 constituting the telescopic structure and the multiple ball spline mechanisms. Furthermore, the multiple ball spline mechanisms can be housed inside the arm 10, thus achieving increased rigidity without increasing the size of the arm 10 of the telescopic structure. Of course, the ball spline mechanisms added to strengthen the arm 10 are also linear motion mechanisms, just like the telescopic structure itself, and therefore do not impede the linear motion of the arm 10.

[0040] Furthermore, the structure of the arm of a linear mechanism is not limited to a telescopic structure. For example, the linear element constituting the arm may not be a cylindrical body, but rather an element composed of a linear guide and a moving body that moves along the linear guide. In a variation, an example will be given using a cylindrical rod as the linear guide and a plate-shaped moving plate as the moving body.

[0041] like Figure 10 , Figure 11 As shown, the modified direct-acting mechanism 2 has a plate-shaped base 100 and an arm 50 supported by the base 100 and capable of free extension and retraction. The arm 50 is composed of multiple rods, here four rods 51, 53, 55, and 57, and multiple movable plates 73, 75, and 77 connecting adjacent rods.

[0042] like Figures 13 to 18 As shown, among the multiple rods 51, 53, 55, and 57, the last rod 51 is fixed to the base 100 with its rear end aligned parallel to a specific axis (moving axis) CL2. A first moving plate 73 is connected to the last rod 51 via a sliding bearing 63 in a freely movable manner. The rear end of rod 53 is fixed to the first moving plate 73 with its orientation parallel to the moving axis CL2. A second moving plate 75 is connected to rod 53 via a sliding bearing 65 in a freely movable manner. The rear end of rod 55 is fixed to the second moving plate 75 with its orientation parallel to the moving axis CL2. A third moving plate 77 is connected to rod 55 via a sliding bearing 67 in a freely movable manner. The rear end of the first rod 57 is fixed to the third moving plate 77 with its orientation parallel to the moving axis CL2.

[0043] The arm 10, constructed as described above, can extend and retract along the moving axis CL2. Because a sliding bearing is located between the rod and the moving plate, the arm 50 itself also possesses a certain degree of rigidity. The direct-acting mechanism 2 has multiple ball spline mechanisms as a reinforcing structure to further improve the rigidity of the arm 50. The ball spline mechanisms are located between two adjacent moving plates.

[0044] like Figure 13 As shown, the first spline shaft 81, constituting the first ball spline mechanism, is fixed to the base 100 with its rear end aligned parallel to the moving shaft CL2. The first spline nut 82, into which the first spline shaft 81 is inserted, is fixed to the first moving plate 73. Figure 15 As shown, the second spline shaft 83, constituting the second ball spline mechanism, is fixed to the first moving plate 73 with its rear end facing parallel to the moving shaft CL2. The second spline nut 84, into which the second spline shaft 83 is inserted, is fixed to the second moving plate 75. Figure 17 As shown, the third spline shaft 85, which constitutes the third ball spline mechanism, is fixed to the second moving plate 75 with its rear end facing parallel to the moving shaft CL2, and the third spline nut 86, which is inserted into the third spline shaft 85, is fixed to the third moving plate 77.

[0045] like Figure 14 , Figure 16 , Figure 18As shown, when the arm 50 has been retracted, in order to prevent the first ball spline mechanism and rod 51 from colliding with the second moving plate 75 and the third moving plate 77, as follows: Figure 13 As shown, openings 751 and 752 are provided on the second movable plate 75, and openings 771 and 772 are provided on the third movable plate 77. Openings 752 and 772 are respectively located on the centerline of the first spline shaft 81 and are respectively sized to allow the first ball spline mechanism to pass through. Openings 751 and 771 are respectively located on the centerline of the rod 51 and are respectively sized to allow the rod 51 to pass through. When the arm 10 has been retracted, in order to prevent the second ball spline mechanism and the rod 53 from colliding with the third movable plate 77, as shown... Figure 15 As shown, other openings 773 and 774 are provided on the third movable plate 77. Opening 774 is formed on the center line of the second spline shaft 83 and is sized to allow the second ball spline mechanism to pass through. Other openings 773 are formed on the center line of the rod 53 and are sized to allow the rod 53 to pass through.

[0046] In addition, such as Figure 12 As shown, the first spline shaft 41, the second spline shaft 43, and the third spline shaft 45 are arranged at equal intervals on a circumference centered on the moving shaft CL2. This allows for improved torsional rigidity while maintaining the weight balance of the arm 50. Furthermore, as... Figure 12 As shown, by arranging the rod and ball spline mechanism close to the moving shaft CL2, the enlargement of the arm 50 can be suppressed.

[0047] Of course, in order to improve the rigidity of the arm 10, it is preferable that the first spline shaft 81, which is fixed on the base 100 at the root of the arm 50, is thicker than the second spline shaft 83 and the third spline shaft 85. In addition, in order to make the direct-acting mechanism lightweight, it is preferable that the third spline shaft 85 at the front end of the arm 50 is thinner than the first spline shaft 81 and the second spline shaft 83.

[0048] According to the above description of the linear action mechanism 2, the load applied to the arm 10 can be distributed to two mechanisms: multiple linear action elements (rods and moving plates) connected in series and multiple ball spline mechanisms. In addition, since multiple ball spline mechanisms can be arranged close to the moving shaft CL2, the rigidity can be improved without making the arm 50 larger.

[0049] While some embodiments have been described, these embodiments are presented by way of example only and are not intended to limit the scope of the invention. In fact, the novel methods and systems described herein can be embodied in various other forms; furthermore, various omissions, substitutions, and modifications can be made to the implementation of the methods and systems described herein without departing from the spirit of the invention. The appended claims and their equivalents are intended to cover forms or modifications falling within the scope and spirit of the invention.

Claims

1. A direct acting mechanism characterized in that, Having: a plurality of cylindrical bodies that are freely movable with respect to each other and are configured in a multi-stage nested structure; a plurality of shafts that are housed inside the cylindrical bodies; a plurality of sliders that are respectively engaged with the plurality of shafts in a freely movable manner; and a plurality of sliding bearings that are provided to inner circumferential surfaces of front ends of the cylindrical bodies, the shafts are fixed to one of the adjacent cylindrical bodies among the plurality of cylindrical bodies, the sliders are fixed to the other of the adjacent cylindrical bodies, the adjacent cylindrical bodies are connected in a freely movable manner via the sliding bearings, the plurality of cylindrical bodies are freely movable in a horizontal direction by the combination of the plurality of shafts and the plurality of sliders and the plurality of sliding bearings, the plurality of shafts are collectively arranged in a range of an upper half of the inside of the cylindrical bodies that deviates from a cylinder center line of the cylindrical bodies.

2. The direct motion mechanism according to claim 1, wherein a drive mechanism that drives movement of the plurality of cylindrical bodies is housed in a range of a lower half of the inside of the cylindrical bodies that deviates from the cylinder center line across the cylinder center line.

3. The direct motion mechanism according to claim 1, wherein a specific shaft that is fixed to a last-stage cylindrical body among the plurality of cylindrical bodies has a diameter that is thicker than diameters of other shafts, and is arranged at a position that is higher than the other shafts.

4. The direct motion mechanism according to any one of claims 1 to 3, wherein the shafts and the sliders together constitute a ball spline mechanism.

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