Lead screw unit and lead screw system

Abstract

A lead screw unit according to the present disclosure comprises a shaft part that extends along the axial direction, a first holder part that rotatably holds one end of the shaft part, a second holder part that rotatably holds the other end of the shaft part, a first support part that supports the first holder part, and a second support part that supports the second holder part. A nut is provided with a cutout part penetrating in the axial direction. The width of the first support part and / or the second support part is smaller than the width of the cutout part of the nut.

Description

Feed screw unit and feed screw system

[0001] The present disclosure relates to a lead screw unit and a lead screw system.

[0002] Conventionally, there is a feed screw mechanism as a mechanism for converting rotational motion into translational motion. A typical feed screw mechanism includes a screw and a nut, and rotating one of them translates the other. A well-known example of this feed screw mechanism is a mechanical screw that is driven by contact force. Another example of this feed screw mechanism is a magnetic screw that transmits power using magnetic force. For example, Patent Document 1 proposes a magnetic power transmission structure that includes a shaft member and a cylindrical member.

[0003] International Publication No. 2020 / 085162

[0004] The present inventors have discovered that conventional feed screw mechanisms, including mechanical screws and magnetic screws, have the following problems. In conventional feed screw mechanisms, the shaft member (screw) must be lengthened to expand the translational range of the nut. However, there is a limit to how long the shaft member can be extended (i.e., to expand the translational range of the nut).

[0005] In one aspect, the present disclosure has been made in consideration of the above points, and an object of the present disclosure is to provide a technology that can easily widen the translation range of a nut.

[0006] In order to solve the above-mentioned problems, the present disclosure employs the following configurations. Note that the following configurations of the invention can be combined as appropriate.

[0007] A feed screw unit according to one aspect of the present disclosure is used in a nut. The feed screw unit includes a shaft portion having an axis and an outer circumferential surface and extending along an axial direction, a first holder portion rotatably holding one end of the shaft portion, a second holder portion rotatably holding the other end of the shaft portion, a first support portion supporting the first holder portion, and a second support portion supporting the second holder portion. The nut includes a notch portion penetrating in the axial direction. The width of at least one of the first support portion and the second support portion is smaller than the width of the notch portion of the nut.

[0008] In this configuration, the width of at least one of the first support portion and the second support portion is smaller than the width of the notch portion of the nut, so that the nut can be passed from at least one of the support portions to another feed screw unit. Therefore, by using multiple feed screw units, the translation range of the nut can be easily expanded. Therefore, with this configuration, it is possible to easily expand the translation range of the nut.

[0009] The feed screw unit according to the above aspect may further include a rail portion extending along the axial direction so as to be arranged parallel to the shaft portion. The width of the rail portion may be smaller than the width of the notch portion of the nut, so that the rail portion is positioned within the notch portion when the nut is attached to the shaft portion. With this configuration, the notch portion of the nut, which moves between feed screw units, can also be used as a rotation stopper. Therefore, a simplified configuration of the feed screw unit can be expected.

[0010] In the feed screw unit according to the above aspect, the nut may be configured to be driven by magnetic force. A mechanical screw is driven by contact force generated by meshing of a convex portion on the inner peripheral surface of the nut with a convex portion on the outer peripheral surface of the shaft (screw). Compared to this mechanical screw, a magnetic screw can be driven by magnetic force without meshing of the convex portion on the nut with the convex portion on the shaft. Therefore, a magnetic screw can tolerate a larger misalignment between feed screw units than a mechanical screw. Therefore, this configuration using a magnetic screw mechanism can particularly demonstrate the effects of unitizing the feed screw.

[0011] Also, a feed screw system according to one aspect of the present disclosure includes a nut, a first feed screw unit, and a second feed screw unit. Each of the first feed screw unit and the second feed screw unit includes a shaft portion having an axis and an outer circumferential surface and extending along an axial direction, a first holder portion rotatably holding one end of the shaft portion, a second holder portion rotatably holding the other end of the shaft portion, a first support portion supporting the first holder portion, and a second support portion supporting the second holder portion. The nut includes a notch portion penetrating in the axial direction. The second holder portion and the second support portion of the first feed screw unit, and the first holder portion and the first support portion of the second feed screw unit, are configured to be common or adjacent to each other. The width of each of the second support portion of the first feed screw unit and the first support portion of the second feed screw unit is smaller than the width of the notch portion of the nut.

[0012] In this configuration, the width of each of the second support portion of the first feed screw unit and the first support portion of the second feed screw unit is smaller than the width of the notch portion of the nut, allowing the nut to move between the two feed screw units. Therefore, the range of the shaft portions of the first feed screw unit and the second feed screw unit can be secured as the translation range of the nut. Therefore, with this configuration, a wide translation range of the nut can be secured. The number of feed screw units included in the feed screw system is not limited to two, and may be three or more.

[0013] In the feed screw system according to the above aspect, each of the first feed screw unit and the second feed screw unit may further include a rail portion extending along the axial direction so as to be arranged parallel to the shaft portion. In each of the first feed screw unit and the second feed screw unit, the width of the rail portion may be smaller than the width of the notch portion of the nut, so that the rail portion is positioned within the notch portion when the nut is attached to the shaft portion. With this configuration, the notch portion of the nut, which moves between the feed screw units, can also be used as a rotation stopper. Therefore, a simplified configuration of the feed screw system can be expected.

[0014] In the feed screw system according to the above aspect, the nut may be configured to be driven by magnetic force. The outer circumferential surface of the shaft portion of the first feed screw unit may be provided with a first ridge protruding radially outward from the shaft and formed helically around the shaft. The outer circumferential surface of the shaft portion of the second feed screw unit may be provided with a second ridge protruding radially outward from the shaft and formed helically around the shaft. The first ridge of the first feed screw unit and the second ridge of the second feed screw unit may have different helical leads.

[0015] In a magnetic screw, when the shaft portion is rotated at a constant speed, the movement speed of the nut depends on the lead of the protrusions on the shaft portion. In this configuration, the first feed screw unit and the second feed screw unit have different leads of the protrusions on the shaft portion, which allows the movement speed of the nut to be changed. Therefore, with this configuration, the movement speed of the nut in each feed screw unit can be controlled.

[0016] According to the present disclosure, it is possible to easily widen the translation range of the nut.

[0017] FIG. 1 is a perspective view schematically showing an example of a feed screw unit. FIG. 2 is a side view schematically showing an example of a feed screw unit. FIG. 3 is a plan view schematically showing an example of a feed screw unit. FIG. 4 is a front view schematically showing an example of a feed screw unit. FIG. 5 is a cross-sectional view schematically showing an example of a feed screw unit. FIG. 6 is a perspective view schematically showing an example of a magnetic unit in a nut. FIG. 7 is a perspective view schematically showing an example of a relationship between a nut and a rail portion. FIG. 8 is a front view schematically showing an example of a relationship between a nut and a rail portion. FIG. 9 is a perspective view schematically showing an example of a feed screw system. FIG. 10 is a side view schematically showing an example of a feed screw system. FIG. 11 is a perspective view schematically showing another example of a magnetic unit.

[0018] Hereinafter, an embodiment according to one aspect of the present disclosure will be described with reference to the drawings. However, the embodiment described below is merely an example of the present disclosure in all respects. Various improvements and modifications may be made without departing from the scope of the present disclosure. In other words, when implementing the present disclosure, specific configurations according to the embodiment may be appropriately adopted. Note that, for convenience of explanation, the following description will be made based on the orientation of the drawings.

[0019] §1 Configuration Example FIGS. 1, 2, 3, 4, and 5 are a perspective view, a side view, a plan view, a front view, and a cross-sectional view that schematically show an example of a feed screw unit 1 according to this embodiment.

[0020] For ease of explanation, each diagram illustrates directions using the x-axis, y-axis, and z-axis. The y-axis direction corresponds to a direction perpendicular to the ground (up-down / vertical direction), and the positive direction of the y-axis corresponds to a vertically upward direction. The xz plane corresponds to a plane horizontal to the ground, and the x-axis and z-axis directions correspond to directions horizontal to the ground. For ease of explanation, the positive and negative directions of the x-axis will be referred to as "left" and "right," respectively, and the positive and negative directions of the z-axis will be referred to as "front" and "back," respectively.

[0021] The feed screw unit 1 according to this embodiment is used for a nut 5. The feed screw unit 1 includes a shaft portion 10, a first holder portion 11, a second holder portion 12, a first support portion 13, a second support portion 14, a rail portion 15, and a base 16.

[0022] [Shaft Portion] The shaft portion 10 has an axis 100 and an outer peripheral surface 101 and extends along the axial direction (z-axis direction). The shape of the shaft portion 10 may be selected arbitrarily. In the examples shown in the figures, the shaft portion 10 is formed in a cylindrical shape. The shaft portion 10 may be solid or hollow. The outer peripheral surface 101 of the shaft portion 10 is provided with ribs 105 that protrude radially outward from the axis 100. The ribs 105 are formed around the axis. The ribs 105 around the axis refer to the direction of rotation (circumferential direction) around the axis 100. The radial direction refers to the direction in a plane (x-y plane) perpendicular to the axial direction (i.e., the radial direction of a circle centered on the axis 100). The shaft portion 10 corresponds to the screw of a feed screw mechanism. The shaft portion 10 may be formed as a single unit or may be composed of two or more parts. For example, the ribs 105 and other parts of the shaft portion 10 may be formed as a single unit or as separate parts.

[0023] [Holder portion / support portion] The first holder portion 11 rotatably holds one end 108 of the shaft portion 10. The second holder portion 12 rotatably holds the other end 109 of the shaft portion 10. In the example of each figure, when viewed from the front, the first holder portion 11 is disposed on the front side, and the second holder portion 12 is disposed on the rear side. However, the arrangement of the first holder portion 11 and the second holder portion 12 is not limited to this example, and they may be interchanged.

[0024] The first support portion 13 is configured to support the first holder portion 11. The second support portion 14 is configured to support the second holder portion 12. In this embodiment, the first support portion 13 and the second support portion 14 are arranged spaced apart in the front-to-rear direction (z-axis direction) on a flat base 16. Each support portion (13, 14) is formed in an inverted T shape. Each support portion (13, 14) is fixed onto the base 16. The fixing method may be selected arbitrarily. In one example, each support portion (13, 14) may be fixed by screwing on both sides of the legs of the inverted T. In another example, each support portion (13, 14) may be fixed by adhesive.

[0025] In this embodiment, each holder portion (11, 12) is disposed on each support portion (13, 14). That is, each support portion (13, 14) supports each holder portion (11, 12) from below. Each holder portion (11, 12) and each support portion (13, 14) may be integrally formed or may be composed of separate parts. If composed of separate parts, each holder portion (11, 12) may be appropriately fixed to each support portion (13, 14).

[0026] The nut 5 has a hollow portion 52 and a notch portion 59. The hollow portion 52 is formed to penetrate in the axial direction near the center of a plane perpendicular to the axial direction (xy plane). During use, the shaft portion 10 is inserted into the hollow portion 52. In the example shown in each figure, the cross section of the hollow portion 52 perpendicular to the axial direction is formed to be approximately circular. The hollow portion 52 may be formed to have approximately the same diameter as the shaft portion 10 or a slightly larger diameter. The notch portion 59 extends radially outward from the hollow portion 52 of the nut 5 so as to open from the hollow portion 52 to a portion of the outer periphery around the axis of the nut 5. The notch portion 59 is formed to penetrate in the axial direction. In the example shown in each figure, the notch portion 59 extends downward from the hollow portion 52. The cross section of the notch portion 59 perpendicular to the axial direction is formed to be approximately rectangular.

[0027] The width of at least one of the first support portion 13 and the second support portion 14 is smaller than the width of the notch portion 59 of the nut 5. The width is the length in the direction perpendicular to the axial direction (x-axis direction). As a result, at least one of the first support portion 13 and the second support portion 14 is configured to allow the nut 5 to pass through in order to transfer the nut 5 to another feed screw unit. When the nut 5 passes through at least one of the support portions, the holder portion supported by the at least one support portion passes through the hollow portion 52 of the nut 5. Therefore, in a plane perpendicular to the axial direction, at least one of the first holder portion 11 and the second holder portion 12 (the holder portion on the side through which the nut 5 passes) is formed smaller (for example, with a smaller diameter) than the hollow portion 52 of the nut 5.

[0028] When two or more feed screw units 1 are connected and used, the holder portion and support portion between two adjacent feed screw units 1 are configured to allow the nut 5 to pass through. The holder portion and support portion between two adjacent feed screw units 1 may be provided separately or may be provided in common (i.e., may be configured as an integrated unit). When the latter is adopted, for example, the second holder portion 12 and the second support portion 14 of one of the two adjacent feed screw units 1 may also serve as the first holder portion 11 and the first support portion 13 of the other. When the former is adopted, for example, the second holder portion 12 and the second support portion 14 of one of the two adjacent feed screw units 1 may be disposed adjacent to the first holder portion 11 and the first support portion 13 of the other so that the nut 5 can be passed to the other. Furthermore, when the shaft portion 10 is configured to rotate around its axis to translate the nut 5, when transferring the nut 5 from one of two adjacent feed screw units 1 to the other, the other shaft portion 10 may be rotated around its axis as appropriate to match the nut 5 to be received.

[0029] [Nut] The type of nut 5 is not particularly limited and may be selected appropriately depending on the embodiment. A mechanical screw mechanism or a magnetic screw mechanism may be used as the feed screw mechanism for the nut 5 and the shaft portion 10. In this embodiment, the nut 5 is configured to be driven by magnetic force. That is, a magnetic screw mechanism is used as the feed screw mechanism for the nut 5 and the shaft portion 10.

[0030] In the example of FIG. 5 , the nut 5 includes a housing 50, a lid 51, a hollow portion 52, an inner peripheral surface 53, and two magnetic units 6. The housing 50 is formed in a cylindrical shape and has an internal space. One end of the housing 50 is open. The circular lid 51 is attached to the open opening at one end of the housing 50. In this way, the lid 51 is configured to close the open opening. The method of attaching the lid 51 is not particularly limited and may be selected appropriately depending on the embodiment. The other end of the housing 50 and the lid 51 have an opening corresponding to the hollow portion 52. The magnetic unit 6 is housed in the internal space within this housing 50.

[0031] (Magnetic Unit) FIG. 6 is a perspective view schematically illustrating an example of the magnetic unit 6 in the nut 5. The magnetic unit 6 includes a cylindrical unit 7, a first magnet 81, a first magnet 82, a second magnet 83, and a second magnet 84. In one example, the cylindrical unit 7 is formed in a cylindrical shape and has a hollow portion penetrating in the axial direction and an inner circumferential surface in contact with the hollow portion. When the magnetic unit 6 is housed in the housing 50, the hollow portion of the magnetic unit 6 forms at least a portion of the hollow portion 52 of the nut 5, and the inner circumferential surface of the magnetic unit 6 forms at least a portion of the inner circumferential surface 53 of the nut 5. A convex portion 54 protruding radially outward is formed on the inner circumferential surface 53 so as to face the ridge 105 of the shaft portion 10.

[0032] At least one of the ribs 105 of the shaft portion 10 and the convex portions 54 of the nut 5 is formed in a spiral shape around the axis. The spiral shape may be continuous or discontinuous, as long as the position of the convexity is shifted in the axial direction over one revolution around the axis. For example, the spiral shape may include a shape that extends continuously while rotating in the axial direction, or a shape in which multiple convexities are arranged in a discontinuous manner, shifting their positions around the axis, like a spiral staircase. Furthermore, the type of spiral may be selected arbitrarily. The type of spiral may be selected arbitrarily from known types, such as single-start threads and double-start threads. If one of the ribs 105 of the shaft portion 10 and the convex portions 54 of the nut 5 is not formed in a spiral shape, the shape of the other may be selected arbitrarily. For example, one of the ribs 105 of the shaft portion 10 and the convex portions 54 of the nut 5 may be formed in a shape that does not shift in the axial direction, such as a circumferential shape or an arc shape. The shapes of the ridge 105 of the shaft portion 10 and the convex portion 54 of the nut 5 are not particularly limited, and may be determined appropriately depending on the embodiment.

[0033] Furthermore, the opposing relationship between the ribs 105 of the shaft portion 10 and the convex portions 54 of the nut 5 may be achieved by timing when at least portions of the ribs 105 and the convex portions 54 are opposed to each other while the shaft portion 10 is being rotated about its axis relative to the nut 5. In one example, when the ribs 105 of the shaft portion 10 and the convex portions 54 of the nut 5 are both formed in a spiral shape, the spirals of the ribs 105 and the convex portions 54 may be configured to coincide (i.e., have the same spiral lead). However, the spirals of the ribs 105 and the convex portions 54 do not necessarily have to be configured in this manner. In another example, the spiral leads of the ribs 105 and the convex portions 54 may not coincide, and the ribs 105 and the convex portions 54 may be configured such that at least portions of the ribs 105 are opposed to at least portions of the convex portions 54 while the shaft portion 10 is being rotated about its axis relative to the nut 5.

[0034] In the examples shown in the figures, grooves (recesses) are formed in the outer peripheral surface 101 of the shaft portion 10 as gaps between the protrusions 105. In one example, these grooves may be filled with an insulating material such as resin. As a result, the outer peripheral surface 101 of the shaft portion 10 may be formed so that there are no apparent irregularities. The area filled with the insulating material does not have to be limited to the grooves. The insulating material may be filled to include the protrusions 105. Similarly, grooves (recesses) are formed in the inner peripheral surface 53 of the nut 5 as gaps between the protrusions 54. In one example, these grooves may be filled with an insulating material such as resin. As a result, the inner peripheral surface 53 of the nut 5 may be formed so that there are no apparent irregularities. The area filled with the insulating material does not have to be limited to the grooves. The insulating material may be filled to include the protrusions 54.

[0035] In one example, a pair of grooves (91, 92) penetrating in the axial direction are provided at the top and bottom of the cylindrical unit 7. The groove 92 arranged on the lower side is connected to the hollow portion and constitutes part of the cutout portion 59. In the example of Fig. 6, each of the grooves (91, 92) is formed in a substantially rectangular shape. However, the shape of each of the grooves (91, 92) is not limited to this example and may be changed as appropriate depending on the embodiment.

[0036] Furthermore, in one example, a pair of grooves (75, 76) are provided on the outer peripheral surface of the cylindrical unit 7, each formed around the axis (in a ring shape) at a position away from the axial end. The pair of grooves (75, 76) are formed at positions away from each other in the axial direction. The pair of grooves (75, 76) divide the cylindrical unit 7 into three parts: a first part 71, a second part 72, and a third part 73. The parts (71, 72, 73) and the inner peripheral part of the cylindrical unit 7 may be integrally formed or may be composed of two or more parts. In the example shown in FIG. 6 , a first magnet 81 and a first magnet 82 are arranged adjacent to each other around the axis in one groove 75. A second magnet 83 and a second magnet 84 are arranged adjacent to each other around the axis in the other groove 76.

[0037] Each magnet (81, 82, 83, 84) may be a permanent magnet or an electromagnet. Each magnet (81, 82, 83, 84) is magnetized in the axial direction. Each magnet (81, 82, 83, 84) is formed in an arc shape. The angle of the arc of each magnet (81, 82, 83, 84) may be 180 degrees or less. The arc shape may include a shape with a missing part (quasi-arc shape), such as an arch shape. The shapes of each magnet (81, 82, 83, 84) may be the same or may be at least partially different.

[0038] The first magnet 1 81 and the first magnet 2 82 are spaced apart in the left-right direction by an insulating layer to prevent them from contacting each other. Similarly, the second magnet 1 83 and the second magnet 2 84 are spaced apart in the left-right direction by an insulating layer to prevent them from contacting each other. Each groove (91, 92) acts as an insulating layer between the first magnet 1 81 and the first magnet 2 82, and between the second magnet 1 83 and the second magnet 2 84. The groove 91, which is unrelated to the passage of the support part, may be filled with an insulating material such as resin.

[0039] The first magnet 81 and the second magnet 83 are arranged to face each other in the axial direction. The first magnet 82 and the second magnet 84 are arranged to face each other in the axial direction. Each magnet (81, 82, 83, 84) has two end faces in the axial direction (z-axis direction). The first magnet 81 and the second magnet 84 may each be magnetized so that the end face on one side in the axial direction is the north pole. The first magnet 82 and the second magnet 83 may each be magnetized so that the end face on the other side in the axial direction is the north pole. In other words, the first magnet 81 and the second magnet 84 may be combined so that they are magnetized in the same axial direction. The first magnet 82 and the second magnet 83 may be combined so that they are magnetized in the same axial direction (the opposite direction to the magnetization direction of the first magnet 81 and the second magnet 84).

[0040] As an example, assume that the first magnet 81 and the second magnet 84 are magnetized so that their end faces on the positive side of the z-axis are north poles, and the first magnet 82 and the second magnet 83 are magnetized so that their end faces on the negative side of the z-axis are north poles. In this situation, in the range where the convex portion 54 of the nut 5 and the rib 105 of the shaft portion 10 face each other, the magnetic flux emitted from the first magnet 81 passes through the area of ​​the second portion 72 adjacent to the first magnet 81, the area of ​​the shaft portion 10 and the first magnet 82 adjacent to the second portion 72, and then heads toward the first magnet 82. The magnetic flux emitted from the first magnet 82 passes through the area of ​​the first portion 71 adjacent to the first magnet 82, the area of ​​the shaft portion 10 and the first magnet 81 adjacent to the first magnet 81, and then heads toward the first magnet 81. This forms a magnetic circuit that passes through the first magnet 81 and the first magnet 82.

[0041] Similarly, in the area where the protrusion 54 of the nut 5 and the rib 105 of the shaft portion 10 face each other, the magnetic flux emitted from the second magnet 1 83 passes through the area adjacent to the second magnet 1 83 in the second portion 72, the area adjacent to the second magnet 2 84 in the shaft portion 10 and the second portion 72, and then passes toward the second magnet 2 84. The magnetic flux emitted from the second magnet 2 84 passes through the area adjacent to the second magnet 2 84 in the third portion 73, the area adjacent to the second magnet 1 83 in the shaft portion 10 and the third portion 73, and then passes toward the second magnet 1 83. This forms a magnetic circuit passing through the second magnet 1 83 and the second magnet 2 84. When at least one of the nut 5 and the shaft portion 10 is rotated around its axis, the formation of these magnetic circuits can generate thrust. Note that the magnetization directions of the magnets (81, 82, 83, 84) may be opposite.

[0042] In the example of FIG. 5 , two magnetic units 6 are housed in the housing 50. However, the number of magnetic units 6 housed in the housing 50 is not limited to two, and may be one, or three or more. When the nut 5 includes multiple magnetic units 6, each magnetic unit 6 may be configured to be able to change its phase around the axis. By aligning the phases of the magnets (81, 82, 83, 84) in each magnetic unit 6, the thrust can be increased. On the other hand, by shifting the phases of the magnets (81, 82, 83, 84) between the magnetic units 6, the thrust can be reduced.

[0043] [Rail Portion] The rail portion 15 extends along the axial direction so as to be arranged parallel to the shaft portion 10. In the example shown in each figure, the rail portion 15 bridges between the first support portion 13 and the second support portion 14 below the shaft portion 10. Each end of the rail portion 15 may be appropriately fixed to each support portion (13, 14). The width (length in the x-axis direction) of the rail portion 15 is smaller than the width of the notch portion 59 of the nut 5. As a result, when the nut 5 is attached to the shaft portion 10, the rail portion 15 is positioned within the notch portion 59. This rail portion 15 acts as a rotation stopper for the nut 5. In the example shown in each figure, the rail portion 15 is formed in a rectangular column shape. However, the shape of the rail portion 15 is not particularly limited as long as it can be positioned within the notch portion 59, and may be appropriately changed depending on the embodiment.

[0044] 7 and 8 are a perspective view and a front view, respectively, schematically illustrating an example of the relationship between the nut 5 and the rail portion 15. In the example illustrated in FIGS. 7 and 8, the housing 50 is formed larger radially outward than the magnetic unit 6 inside. The width of the cutout portion 59 in the housing 50 (and the lid portion 51) is larger than the groove 92 in the magnetic unit 6 (cylindrical unit 7). The width of the rail portion 15 is smaller than the width of the cutout portion 59 in the housing 50 and larger than the groove 92 in the magnetic unit 6. Therefore, the rail portion 15 is disposed adjacent to the magnetic unit 6 on the radially outer side (below) of the magnetic unit 6. The rail portion 15 may extend radially outward (below) from the cutout portion 59.

[0045] Arranging the rail portion 15 in this manner allows for flexibility in the width of the groove 92. However, the relationship between the notch portion 59 in the housing 50 portion and the groove 92 and the arrangement of the rail portion 15 are not limited to this example and may be changed as appropriate depending on the embodiment. In another example, the width of the groove 92 may be the same as or larger than the notch portion 59 in the housing 50 portion. As long as the support portion can pass through, the width of the notch portion 59 including the groove 92 may be determined arbitrarily. The rail portion 15 may be arranged inside the groove 92.

[0046] [Materials / Manufacturing Method] A magnetic material may be used as the material for the shaft portion 10 and the cylindrical unit 7 of each magnetic unit 6 of the nut 5. In one example, a soft magnetic material, carbon steel, or the like may be used for the shaft portion 10 and the cylindrical unit 7. Examples of soft magnetic materials include soft electromagnetic iron, silicon steel, and amorphous magnetic alloys. A known ball screw may be used for the shaft portion 10. A non-magnetic material may be used for the housing 50 and the lid portion 51. A bearing holder may be used for each holder portion (11, 12). A non-magnetic material may also be used for each support portion (13, 14), rail portion 15, and base 16. Examples of non-magnetic materials include aluminum, stainless steel, and resin.

[0047] As an example of a manufacturing method, a cylindrical magnetic material is prepared, and the outer peripheral surface of the prepared magnetic material is machined to manufacture the shaft portion 10 having the protrusions 105. The support portions (13, 14) may be manufactured as appropriate. The support portions (13, 14) are fixed to the base 16, and the rail portion 15 and the holder portions (11, 12) are attached to the support portions (13, 14). Then, the ends (108, 109) of the shaft portion 10 are held by the holder portions (11, 12). In this way, the feed screw unit 1 can be manufactured.

[0048] The outer periphery of the cylindrical unit 7 can be fabricated by preparing a cylindrical magnetic material and forming grooves (75, 76, 91, 92) on the outer periphery of the prepared magnetic material using any processing method, such as cutting. The cylindrical unit 7 can also be fabricated by drilling axial holes in the magnetic material and carving the teeth of the protrusions 54 into the inner periphery. The magnetic unit 6 can be fabricated by placing magnets (81, 82, 83, 84) in the grooves (75, 76) of the fabricated cylindrical unit 7. The housing 50 and the lid 51 may be fabricated as appropriate. The nut 5 can be fabricated by housing the magnetic unit 6 in the housing 50 and closing the opening of the housing 50 with the lid 51. The nut 5 may be attached to the shaft 10 as appropriate. The fabrication method is not limited to this example and may be modified as appropriate depending on the embodiment.

[0049] [Characteristics of the Feed Screw Unit] In this embodiment, the width of at least one of the first support portion 13 and the second support portion 14 is smaller than the width of the notch portion 59 of the nut 5, so that the nut 5 can be passed from one feed screw unit 1 to another feed screw unit 1 via at least one support portion. Therefore, by using multiple feed screw units 1, the translation range of the nut 5 can be easily widened. Therefore, the feed screw unit 1 according to this embodiment makes it possible to easily widen the translation range of the nut 5. In one example, a feed screw system may be configured with the nut 5 and two or more feed screw units 1.

[0050] In addition, in one example of this embodiment, by arranging the rail portion 15 inside the notch portion 59 of the nut 5, the notch portion 59 of the nut 5 for moving between the feed screw units 1 can also be used as a rotation stopper. As a result, according to this example of the present embodiment, it is expected that the configuration of the feed screw unit 1 can be simplified.

[0051] Furthermore, in one example of this embodiment, the nut 5 is configured to be driven by magnetic force. That is, a magnetic screw mechanism is used for the feed screw mechanism of the nut 5 and the shaft portion 10. A magnetic screw can be driven by magnetic force even if the convex portion of the nut and the convex portion of the shaft do not mesh. Therefore, a magnetic screw can tolerate a larger misalignment between the feed screw units than a mechanical screw. Therefore, in this example of this embodiment that uses a magnetic screw mechanism, the effect of unitizing the feed screw can be particularly demonstrated.

[0052] 9 and 10 are a perspective view and a side view schematically illustrating an example of a feed screw system S according to this embodiment. In the example shown in FIGS. 9 and 10, the feed screw system S includes a nut 5, a first feed screw unit 1A, a second feed screw unit 1B, and a third feed screw unit 1C. Each of the feed screw units (1A, 1B, 1C) is an example of the feed screw unit 1. Each of the feed screw units (1A, 1B, 1C) may be configured similarly to the feed screw unit 1. That is, each of the feed screw units (1A, 1B, 1C) includes a shaft portion 10, a first holder portion 11, a second holder portion 12, a first support portion 13, a second support portion 14, a rail portion 15, and a base 16.

[0053] The second holder portion 12 and the second support portion 14 of the first feed screw unit 1A, and the first holder portion 11 and the first support portion 13 of the second feed screw unit 1B, are configured to be common or adjacent. Similarly, the second holder portion 12 and the second support portion 14 of the second feed screw unit 1B, and the first holder portion 11 and the first support portion 13 of the third feed screw unit 1C, are configured to be common or adjacent. In the example shown in Figures 9 and 10, the second holder portion 12 and the second support portion 14, and the first holder portion 11 and the first support portion 13 are common between the adjacent first feed screw unit 1A and the second feed screw unit 1B, and between the adjacent second feed screw unit 1B and the third feed screw unit 1C.

[0054] The width of each of the second support portion 14 of the first feed screw unit 1A, the first support portion 13 of the second feed screw unit 1B, the second support portion 14 of the second feed screw unit 1B, and the first support portion 13 of the third feed screw unit 1C is smaller than the width of the notch portion 59 of the nut 5. Furthermore, in a plane perpendicular to the axial direction, the second holder portion 12 of the first feed screw unit 1A, the first holder portion 11 of the second feed screw unit 1B, the second holder portion 12 of the second feed screw unit 1B, and the first holder portion 11 of the third feed screw unit 1C are formed smaller than the hollow portion 52 of the nut 5.

[0055] In the feed screw system S according to this embodiment, the nut 5 is movable between the three feed screw units (1A, 1B, and 1C). Therefore, the range of the shaft portions 10 of the three feed screw units (1A, 1B, and 1C) can be secured as the translation range of the nut 5. Therefore, the feed screw system S according to this embodiment can secure a wide translation range for the nut 5. Furthermore, in one example of this embodiment, by arranging a rail portion 15 within the cutout portion 59 of the nut 5 in each feed screw unit (1A, 1B, and 1C), the cutout portion 59 of the nut 5 for moving between the feed screw units 1 can also be used as a rotation stopper. As a result, according to this example of this embodiment, the configuration of the feed screw system S can be expected to be simplified.

[0056] In one example, in the feed screw system S, the shaft portions 10 of the feed screw units (1A, 1B, 1C) may be configured to rotate about their axes in an interlocking manner. For example, the shaft portions 10 of the feed screw units (1A, 1B, 1C) may be connected at their ends and configured to rotate integrally with one another by a single motor. Also, for example, a separate motor may be provided for each feed screw unit (1A, 1B, 1C), and the motors may be driven in an interlocking manner, thereby allowing the shaft portions 10 of the feed screw units (1A, 1B, 1C) to rotate in an interlocking manner.

[0057] In one example of this embodiment, the nut 5 is configured to be driven by magnetic force. Accordingly, the ridges 105 provided on the outer peripheral surface 101 of the shaft portion 10 of each feed screw unit (1A, 1B, 1C) may be formed in a spiral shape around the axis. The ridges 105 of the first feed screw unit 1A may be referred to as first ridges. The ridges 105 of the second feed screw unit 1B may be referred to as second ridges. The ridges 105 of the third feed screw unit 1C may be referred to as third ridges. The helical leads of the ridges 105 of at least two of the three feed screw units (1A, 1B, 1C) may be different. For example, the helical leads of the ridges of the first feed screw unit 1A and the second feed screw unit 1B may be different. The lead refers to the amount (length) of axial displacement of the ridge during one revolution around the axis.

[0058] In a magnetic screw, when the shaft portion 10 is rotated around its axis at a constant speed, the movement speed of the nut 5 depends on the lead of the protrusion 105 of the shaft portion 10. The shorter the lead of the protrusion 105, the slower the movement speed of the nut 5, and the longer the lead of the protrusion 105, the faster the movement speed of the nut 5. According to one example of this embodiment, the movement speed of the nut 5 can be changed by varying the lead of the protrusion 105 between the feed screw units (1A, 1B, 1C). This makes it possible to control the movement speed of the nut 5 in each feed screw unit (1A, 1B, 1C).

[0059] In another example, the lead of the ridge 105 of the shaft portion 10 may be constant in each of the feed screw units (1A, 1B, 1C). Also, within one feed screw unit, the lead of the spiral of the ridge 105 of the shaft portion 10 may be constant or variable. As described above, by making the lead of the ridge 105 variable, the moving speed of the nut 5 can be controlled even within one feed screw unit.

[0060] §2 Modifications Although the embodiments of the present disclosure have been described in detail above, the above description is merely an example of the present disclosure in all respects. The processes and means described in the present disclosure can be freely combined and implemented as long as no technical contradictions arise. Various improvements or modifications may be made to the above embodiments as appropriate. With regard to each component of the feed screw unit 1 and feed screw system S, components may be omitted, replaced, or added as appropriate depending on the embodiment. The shape and dimensions of each component are not limited to the examples in the figures and may be changed as appropriate depending on the embodiment.

[0061] <2.1> In the above embodiment, the rail portion 15 is configured to bridge between the two support portions (13, 14). However, the configuration of the rail portion 15 is not limited to this example, and the rail portion 15 may be attached to a location other than the support portions (13, 14). In another example, the rail portion 15 may be supported by a separate member extending from or disposed on the base 16.

[0062] Furthermore, the method for preventing the nut 5 from rotating does not have to be limited to the method using the rail portion 15. The rail portion 15 may be omitted, and the nut 5 may be prevented from rotating by any method other than using the rail portion 15. In another example, both side surfaces (surfaces in the left and right directions) of the nut 5 may be formed flat, and walls may be provided on both sides of the nut 5. In this way, the nut 5 may be configured so that its rotation is prevented by having both side surfaces sandwiched between the walls. Other known methods may be used to prevent the nut 5 from rotating.

[0063] Furthermore, in the above embodiment, the number of rail portions 15 and cutout portions 59 is not limited to one, and may be two or more. In another example, cutout portions may be provided on both side surfaces of the nut 5. Accordingly, the feed screw unit 1 may include a pair of rail portions provided to pass through the cutout portions on both side surfaces.

[0064] <2.2> In the above embodiment, the number of nuts 5 is one. However, the number of nuts 5 is not limited to one, and may be two or more.

[0065] <2.3> In the above embodiment, the nut 5 has the configuration illustrated in Figures 5 and 6, thereby forming a magnetic screw mechanism. However, when a magnetic screw mechanism is adopted, the configuration of the nut 5 does not need to be limited to the example of the above embodiment. The number and arrangement of magnets may be changed as appropriate depending on the embodiment. The magnetization direction of the magnet does not need to be limited to the axial direction. In another example, a magnet magnetized in the radial direction may be used. The configuration of the nut 5 may employ a known configuration proposed in, for example, Patent Document 1. Regarding the configuration of the nut 5, it is possible to omit, replace, or add components as appropriate depending on the embodiment.

[0066] 11 is a perspective view schematically showing an example of a magnetic unit 6A. The magnetic unit 6A is a modified example of the magnetic unit 6. The magnetic unit 6A may be used in place of the magnetic unit 6 in the above embodiment.

[0067] In this magnetic unit 6A (cylindrical unit 7A), the groove 91, which is unrelated to the passage of the support portion, is omitted. As a result, each groove (75, 76) is separated into two grooves (751, 752) (761, 762). Partitions (78, 79) are provided between the grooves (751, 752) (761, 762) around the axis. Each partition (78, 79) may be configured as part of the cylindrical unit 7A. A magnetic material may be used as the material for each partition (78, 79). A first magnet 81 is inserted into the groove 751, and a first magnet 82 is inserted into the groove 752. The partition 78 fills the space between the first magnet 81 and the first magnet 82. Except for the area of ​​the groove 92, the first magnet 81 and the first magnet 82 are continuous around the axis via the partition wall 78. As a result, the first magnet 81 and the first magnet 82 can operate as a single pseudo-arc-shaped magnet. Similarly, the second magnet 83 is inserted into the groove 761, and the second magnet 84 is inserted into the groove 762. The partition wall 79 fills the space between the second magnet 83 and the second magnet 84. Except for the area of ​​the groove 92, the second magnet 83 and the second magnet 84 are continuous around the axis via the partition wall 79. As a result, the second magnet 83 and the second magnet 84 can operate as a single pseudo-arc-shaped magnet. The first magnet 81 and the first magnet 82 may be magnetized so that the end face on one side of the z-axis (axial direction) is a north pole and the end face on the other side of the z-axis is a south pole. The second 1 magnet 83 and the second 2 magnet 84 may be magnetized so that the end faces on the other side of the z axis (axial direction) are the north pole and the end faces on one side of the z axis are the south pole. Except for these points, the cylindrical unit 7A may be configured similarly to the cylindrical unit 7, and the magnetic unit 6A may be configured similarly to the magnetic unit 6.

[0068] As an example, assume that the first magnet 81 and the first magnet 82 are magnetized so that their end faces on the positive side of the z-axis are north poles, and the second magnet 83 and the second magnet 84 are magnetized so that their end faces on the negative side of the z-axis are north poles. In this situation, in the area where the convex portion 54 of the nut 5 and the rib 105 of the shaft portion 10 face each other, magnetic flux emitted from the end face on the positive side of the z-axis of the first magnet 81 passes through the second portion 72, the shaft portion 10, and the first portion 71 toward the end face on the negative side of the z-axis of the first magnet 81. This forms a magnetic circuit by the first magnet 81. Similarly, magnetic flux emitted from the end face on the positive side of the z-axis of the first magnet 82 passes through the second portion 72, the shaft portion 10, and the first portion 71 toward the end face on the negative side of the z-axis of the first magnet 82. This forms a magnetic circuit by the first magnet 82. The magnetic flux emitted from the end face of the second first magnet 83 on the negative side of the z-axis passes through the second portion 72, the shaft portion 10, and the third portion 73, and heads toward the end face of the second first magnet 83 on the positive side of the z-axis. This forms a magnetic circuit by the second first magnet 83. The magnetic flux emitted from the end face of the second second magnet 84 on the negative side of the z-axis passes through the second portion 72, the shaft portion 10, and the third portion 73, and heads toward the end face of the second second magnet 84 on the positive side of the z-axis. This forms a magnetic circuit by the second second magnet 84. These magnetic circuits can generate thrust. The magnetization directions of the first magnet group (the first first magnet 81 and the first second magnet 82) and the second magnet group (the second first magnet 83 and the second second magnet 84) may be opposite.

[0069] The number and arrangement of magnets in the magnetic unit 6A may be modified as appropriate depending on the embodiment. For example, either the first magnet group (first magnet 81 and first magnet 82) or the second magnet group (second magnet 83 and second magnet 84) may be omitted. When a magnet group is omitted, the corresponding groove group (groove into which each magnet is inserted) may also be omitted. Furthermore, for example, in the cylindrical unit 7A, a pair of grooves around the axis may be formed at one or more locations on the z-axis in the range from the pair of grooves around the axis (761, 762) on the positive z-axis side. A partition may be provided between the pair of grooves around the axis. A magnet may be inserted into each of the formed pairs of grooves. As a result, a third or subsequent magnet group may exist. If a third or subsequent magnet group exists, the direction of the end face magnetized to the N pole of each magnet group may alternate. For example, odd-numbered magnet groups (magnets) may be magnetized so that the end face on one side of the z axis (axial direction) of the two end faces is the north pole and the end face on the other side of the z axis is the south pole, while even-numbered magnet groups (magnets) may be magnetized so that the end face on the other side of the z axis (axial direction) of the two end faces is the north pole and the end face on one side of the z axis is the south pole.

[0070] <2.4> In another example, a mechanical screw mechanism may be used for the feed screw mechanism of the nut 5 and the shaft portion 10, instead of a magnetic screw mechanism. When a mechanical screw mechanism is used, the nut 5 is driven by contact force with the shaft portion 10. In this case, the convex portion 54 on the inner circumferential surface 53 of the nut 5 and the ridge 105 on the shaft portion 10 are formed to mesh with each other in a spiral shape. The outer diameter of the shaft portion 10 and the diameter of the hollow portion 52 of the nut 5 are determined so that the convex portion 54 of the nut 5 and the ridge 105 on the shaft portion 10 mesh with each other. Any material other than a magnetic material may be used for the shaft portion 10 and the nut 5. In addition, the materials of each component may be changed as appropriate depending on the embodiment.

[0071] <2.5> In the above embodiment, the base 16 may be omitted. Furthermore, in the above embodiment, each support portion (13, 14) extends vertically upward from the base 16 and supports each holder portion (11, 12) from below. However, the method by which each support portion (13, 14) supports each holder portion (11, 12) is not limited to this example and may be changed as appropriate depending on the embodiment. In another example, each support portion (13, 14) may extend vertically downward from the base 16 and support each holder portion (11, 12) from above. In this way, each holder portion (11, 12) and each support portion (13, 14) may be configured to suspend the shaft portion 10. Other known support methods may be used as appropriate.

[0072] <2.6> In the feed screw system S, the third feed screw unit 1C may be omitted. Furthermore, the feed screw system S may further include a fourth feed screw unit or subsequent feed screw units. In other words, the number of feed screw units 1 used as components of the feed screw system S is not limited to three, and may be two, or four or more.

[0073] DESCRIPTION OF SYMBOLS 1...Feed screw unit, 10...Shaft portion, 100...Axis, 101...Outer peripheral surface, 105...Protrusion, 11...First holder portion, 12...Second holder portion, 13...First support portion, 14...Second support portion, 15...Rail portion, 5...Nut, S...Feed screw system

Claims

1. A feed screw unit used in a nut, comprising: a shaft portion having an axis and an outer peripheral surface and extending along an axial direction; a first holder portion rotatably holding one end of the shaft portion; a second holder portion rotatably holding the other end of the shaft portion; a first support portion supporting the first holder portion; and a second support portion supporting the second holder portion; wherein the nut has a notch portion that passes through in the axial direction, and the width of at least one of the first support portion and the second support portion is smaller than the width of the notch portion of the nut.

2. A feed screw unit as described in claim 1, further comprising a rail portion extending along the axial direction so as to be arranged in parallel with the shaft portion, wherein the width of the rail portion is smaller than the width of the notch portion of the nut, so that when the nut is attached to the shaft portion, the rail portion is arranged within the notch portion.

3. The lead screw unit according to claim 1, wherein the nut is configured to be driven by magnetic force.

4. A feed screw system comprising: a nut; a first feed screw unit; and a second feed screw unit, wherein the first feed screw unit and the second feed screw unit each comprise: a shaft portion having an axis and an outer peripheral surface and extending along the axial direction; a first holder portion rotatably holding one end of the shaft portion; a second holder portion rotatably holding the other end of the shaft portion; a first support portion supporting the first holder portion; and a second support portion supporting the second holder portion, wherein the nut has a notch portion penetrating in the axial direction, and the second holder portion and the second support portion of the first feed screw unit, and the first holder portion and the first support portion of the second feed screw unit, are configured to be common or adjacent to each other, and the width of each of the second support portion of the first feed screw unit and the first support portion of the second feed screw unit is smaller than the width of the notch portion of the nut.

5. The feed screw system described in claim 4, wherein each of the first feed screw unit and the second feed screw unit further comprises a rail portion extending along the axial direction so as to be arranged in parallel with the shaft portion, and in each of the first feed screw unit and the second feed screw unit, the width of the rail portion is smaller than the width of the notch portion of the nut, so that when the nut is attached to the shaft portion, the rail portion is arranged within the notch portion.

6. The feed screw system according to claim 4, wherein the nut is configured to be driven by magnetic force, the outer peripheral surface of the shaft portion of the first feed screw unit is provided with a first ridge that protrudes radially outward from the shaft and is formed in a spiral around the shaft, and the outer peripheral surface of the shaft portion of the second feed screw unit is provided with a second ridge that protrudes radially outward from the shaft and is formed in a spiral around the shaft, and the first ridge of the first feed screw unit and the second ridge of the second feed screw unit have different spiral leads.

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