Lure and weight shift tube for fishing

Abstract

Provided is a lure and a center-of-gravity shifting tube used favorably for assembly to the lure, which, like a fishing lure having a well-known center-of-gravity shifting mechanism, smoothly shifts the center of gravity of the lure and performs a motion that more closely approximates the motion of a small fish swimming in water. The fishing lure is one in which a straight pipe-shaped center-of-gravity shifting tube is fixed to the inside space of a lure body having an elongated space inside, the center-of-gravity shifting tube houses a rod-shaped center-of-gravity body, the center-of-gravity body has a shape that is left-right symmetrical in the width direction and can smoothly shift in the length direction. Furthermore, with regard to the center-of-gravity shifting tube, the center-of-gravity body housed inside is arranged in the inside space of the lure body in such a way that the center axis in the length direction of the center-of-gravity body shifts at a position on the lower side of the center axis in the inside space of the lure body, and with regard to the center-of-gravity body, the cross section in the width direction has a shape in which the plane along the largest diameter of the cross section is a flat top surface, a polygon, a semicircle, or a composite shape that is a combination of these.

Description

Technical Field

[0001] This invention relates to fishing bait with a built-in center of gravity shifting tube and a center of gravity shifting tube suitable for being built into fishing bait. Background Technology

[0002] As a fishing lure used for catching large fish in freshwater areas such as rivers and lakes, or in the sea, it generally utilizes a slender shape that mimics the shape of a small fish that becomes bait, with the hook attached to the belly or tail, etc. For example, as a representative example of fishing operations using lures in the sea, casting fishing is known, in which a lure attached to the tip of the fishing line is cast from the seashore, dock, or ship into the distant sea. In this casting fishing, it is necessary to cast the lure as far as possible, therefore, the lure is often configured to have a weight (weight) embedded inside it.

[0003] Patent Document 1 illustrates a typical series of bait-throwing operations in casting fishing using bait. The bait-throwing operations disclosed in Patent Document 1 will be shown. Figure 1 As Figure 1 This is reproduced in this instruction manual.

[0004] The desired design for a lure hook is that, after being cast into the water, it should move smoothly around the surface or in the water, similar to a live small fish, with its head slightly downwards, as the angler manipulates the rod and line. Therefore, in recent years, fishing lures with built-in center-of-gravity shifting systems for this purpose have been developed and marketed.

[0005] In the aforementioned Patent Document 1, a fishing bait is disclosed, which has an elongated shape that mimics that of a small fish. It includes a bait body (main body) having an elongated space inside and a hook mounted on the main body. A center of gravity shifting system is installed therein, which consists of a guide shaft housed and fixed within the internal space of the main body, and linear bushings with weights at both ends (which function as the center of gravity body) assembled in a manner that enables movement along the front-back direction of the guide shaft.

[0006] Therefore, the specific composition of the fishing bait disclosed in Patent Document 1 will be described below in accordance with the description in claim 1 of its claims.

[0007] The fishing bait disclosed in Patent Document 1 has a bait body with a shape that mimics the appearance of a small fish, and a lip-shaped part that slopes downwards from front to back is attached near the top. A guide shaft is provided from near the front to the rear inside the hollow interior of the bait body. Linear bushings with weights at both ends of the guide shaft are mounted so as to slide back and forth along the guide shaft (acting as a center of gravity). Furthermore, a magnet is mounted near the front end of the bait body, and after the bait is thrown into the sea, the aforementioned linear bushings are magnetically held (magnetically retained) by the magnet.

[0008] The figure shown in the figure disclosed in Patent Document 1, depicting the structure of a fishing bait, is selected and included in the figures of this specification as... Figure 2 Disclosure. The following description, based on Patent Document 1, will explain the... Figure 2 The composition and function of fishing bait.

[0009] Figure 2 (A), (B), and (C) are schematic side cross-sectional views of the bait body, illustrating the overall structure and center-of-gravity shifting system of the fishing bait disclosed in Patent Document 1. Within these views, (A) shows the center-of-gravity shifting system at the beginning of its movement. Figure 1 The image shows the position of the lure 10 before its normal deployment (i.e., during storage) (magnetically held in place by the magnet), (B) the position of the center of gravity immediately after the deployment operation begins, and (C) the position of the center of gravity just before and at the moment of deployment (the center of gravity is near the tail of the lure body). When the lure becomes... Figure 2 After state (C), if the angler pulls the bait closer, the center of gravity moves forward, the magnet remains in front of the magnet, and the angler returns to state (A).

[0010] Figure 3 The fishing bait 10 shown is mainly composed of a hollow bait body (usually manufactured by molding synthetic resin) 11 that mimics the shape of a small fish. At the front end of the bait body 11 (corresponding to the head of a small fish), there is a swivel, to which a fishing line (or line) 13 is attached. From the belly near the front end of the bait body 11 to the rear end, there are multiple hook hangers, each with a front hook (front hook) 18, a middle hook (middle hook) 19, and a rear hook (rear hook) 20 via an open ring. Furthermore, a thin, plate-like lip (acting as a diving board) 21 is mounted on the lower side of the front end of the bait body at a slightly downward angle. Additionally, inside the hollow interior of the fishing bait 10, linear bushings (center of gravity bodies) 23 with weights at both ends are fitted in a manner that allows them to move along the length direction.

[0011] After the fishing bait 10 with this configuration is cast into the water, if the angler pulls the fishing line 13 to bring the bait 10 closer, the lip portion 21 is resisted by the water surrounding the bait. As a result, the center of gravity 23, which is movably mounted inside it, moves forward along the guide shaft 22 and comes into contact with a magnet attached to the front position, thus being temporarily fixed at the front position of the bait. Therefore, the bait body 11 engages in activities such as submerging in the sea or other waters in a forward-leaning posture.

[0012] Figure 3 (A) and (B) are diagrams showing the evolution of the above-mentioned actions in the water immediately after the fishing bait 10 is cast into the water. As shown in (A), the center of gravity 23 is positioned at the rear end of the bait 10 at the moment of casting into the water. Next, if the angler pulls the fishing line 13 to pull the bait 10 forward, the center of gravity 23 moves forward of the bait and comes into contact with the magnet and is temporarily fixed.

[0013] In addition, Figure 2 and Figure 3 The inner circumferential surface of the linear bushing shown in the figure is fitted with a ball bearing (sphere) that rotates while circumferentially moving along the long side of the guide shaft 22, similar to a linear bushing used as a general sliding part. With this configuration of the linear bushing body, the linear bushing moves smoothly forward along the guide shaft depending on the tilt state of the decoy body 11, and is temporarily magnetically fixed to the magnet.

[0014] The fishing bait disclosed in Patent Document 1 can be described as an easy-to-use and excellent fishing bait.

[0015] Patent document 2 discloses a decoy 40 as shown in the figures of this specification. Figure 4 and Figure 5 As shown, the fishing bait described in Patent Document 1 has a hollow interior, but it has a structure in which a straight tube-shaped center-of-gravity shifting tube 41 is built into the space formed inside it. Moreover, the center-of-gravity shifting tube 41 is composed of a cylindrical tube body 41a and a cylindrical center-of-gravity body (weight) 42 housed inside the tube body, and the center-of-gravity body 42 moves smoothly along the length direction inside the tube body.

[0016] Figure 4 and Figure 5The center of gravity 42 shown in the document, capable of the aforementioned movement, is also a linear bushing, but this linear bushing has a cylindrical shape with a ball bearing assembly capable of cyclic movement on its outer circumferential surface. Therefore, the center of gravity moving tube disclosed in Patent Document 2 can be said to be composed of a center of gravity body, which consists of a straight tubular body and a cylindrical linear bushing movably housed inside the tubular body. That is, the cylindrical center of gravity body is a linear bushing with a diameter slightly smaller than the diameter of the inner circumferential surface of the tubular body, and on its outer circumferential surface, three or more rows of ball circulation grooves 44, each consisting of two interconnected grooves, are arranged parallel to each other, the ball circulation grooves 44 cyclically accommodating and holding a number of tiny balls (ball bearings) 43.

[0017] Prior art literature

[0018] Patent documents

[0019] Patent Document 1: Japanese Patent Application Publication No. 2016-82907;

[0020] Patent document 2: WO2018 / 110424 A1. Summary of the Invention

[0021] The problem that the invention aims to solve

[0022] Both of the center-of-gravity shifting mechanisms of the bait described in Patent Document 1 and Patent Document 2 have excellent functions as center-of-gravity shifting mechanisms used in fishing baits.

[0023] However, based on the inventor's discussion, as can be understood from the diagrams disclosed in various patent documents, the guide shaft or center-of-gravity shifting tube, which functions to support the center-of-gravity shifting mechanism within the bait body, is fixed in the interior space of the bait body at a position approximately central in the vertical direction (approximately half the height within the interior space), resulting in the bait's center of gravity being at a relatively high position. Therefore, it is determined that there is a problem: even after being placed in water and the bait's center of gravity is magnetically fixed in front, unnatural swaying (lateral swaying) is likely to occur in the bait, which differs from the natural swimming state exhibited by a live small fish in the water.

[0024] Therefore, the objective of this invention is to provide an improved fishing bait that moves the center of gravity as smoothly as the center of gravity shifting mechanism disclosed in Patent Document 1 or Patent Document 2, and that, after being cast into the water, the bait exhibits natural activity that more closely resembles the natural swimming state of a live small fish in the water.

[0025] Furthermore, the present invention also provides a center-of-gravity shift tube that further enhances the usefulness of the center-of-gravity shift tube as a center-of-gravity shifting mechanism for constituting fishing bait.

[0026] Solution for solving the problem

[0027] In order to solve the aforementioned problems, the inventors of this invention conducted research aimed at improving the center-of-gravity shifting mechanism of the fishing bait disclosed in Patent Document 2 and developing a center-of-gravity shifting tube. Furthermore, as a result, a new structure for the center-of-gravity shifting tube was discovered, which effectively solves the aforementioned problems and provides a center-of-gravity shifting mechanism for the fishing bait. This new structure reduces the placement position (vertical or vertical position or height) of the center-of-gravity shifting tube within the internal space of the fishing bait.

[0028] First, the present invention relates to the following fishing bait.

[0029] A fishing bait has an elongated shape that mimics that of a small fish, comprising a bait body with an elongated internal space and a hook mounted thereon. Within the internal space of the bait body, a center-of-gravity shifting tube with a straight tube shape along its length is fixed. The center-of-gravity shifting tube accommodates a rod-shaped center-of-gravity body, which has a shape that is symmetrical about its width and allows for smooth movement along its length. This fishing bait has the following characteristics:

[0030] (1) Regarding the aforementioned straight-tube-shaped center-of-gravity shifting tube, the center-of-gravity body housed within it is positioned within the interior space of the bait body such that its longitudinal central axis moves below the central axis within the interior space of the bait body.

[0031] (2) Regarding the above-mentioned centroid, its cross section in the width direction has a shape such as a polygon, a semicircle, or a composite shape such as a combination of polygons and semicircles, with the plane along the maximum diameter of the cross section having a flat top surface.

[0032] In addition, a lip-shaped part may be attached to the front part (equivalent to the head of a small fish) of the body of the fishing bait of the present invention, just like the fishing bait described in Patent Document 1 or the fishing bait described in Patent Document 2, but the attachment of the lip-shaped part is arbitrary.

[0033] Secondly, the present invention relates to the following center of gravity shifting tube.

[0034] It is a center-of-gravity moving tube consisting of a tube body that is straight in the length direction and a rod-shaped center-of-gravity body that is symmetrical in the width direction and can be inserted into the inside of the tube body in a way that allows it to move along the length direction of the tube body. Regarding the aforementioned center-of-gravity body, its cross-section in the width direction is a polygon, a semi-circle, or a composite shape such as a combination of polygons and semi-circles with a flat top surface in the plane along the maximum diameter of the cross-section.

[0035] The center-of-gravity shifting tube of the present invention is suitable for use in fishing bait.

[0036] The preferred configuration of the center-of-gravity shifting tube suitable for use in the fishing bait of the present invention described above is as follows.

[0037] (1) It does not have a protrusion on the flat top surface of the center of gravity.

[0038] (2) The cross section of the center of gravity in the width direction has a trapezoidal shape in which the lateral width of the top surface is greater than the lateral width of the bottom surface.

[0039] (3) Regarding the center of gravity, the cross section shows a trapezoidal shape in which the lateral width of the top surface is greater than the lateral width of the bottom surface. Each of the opposite sides of the trapezoid and each of the opposite bottom corners are provided with a spherical circulation groove composed of two interconnected grooves and a sphere filling the spherical circulation groove.

[0040] The effects of the invention

[0041] The fishing bait of the present invention is easy to manufacture, simple in construction, and possesses high strength. Furthermore, its center of gravity is located in a low position (close to the belly of the bait). Therefore, after being cast into the water, the fishing bait of the present invention readily exhibits movements close to the natural swimming behavior of a live small fish. Thus, the fishing bait of the present invention has high value in practical use.

[0042] The center-of-gravity shift tube of the present invention, if used for internal installation in fishing bait, can be easily fitted into a lower position inside the fishing bait. Therefore, fishing bait fitted with the center-of-gravity shift tube of the present invention exhibits movements in water that closely resemble the swimming behavior of a live small fish, thus possessing high value as fishing bait. Attached Figure Description

[0043] Figure 1 It is a schematic diagram showing the overall process of casting a bait attached to a fishing rod into the sea (or water) as disclosed in Patent Document 1.

[0044] Figure 2 This is a schematic diagram showing the overall structure and center of gravity shifting system of the fishing bait disclosed in Patent Document 1.

[0045] Figure 3 It is a diagram showing the evolution of the action of a fishing bait in the sea (or water) after it has been cast onto the surface (or surface) of the sea (or water).

[0046] Figure 4 It schematically shows the overall structure of the fishing bait and the side cross-sectional view of the center of gravity shifting tube disclosed in Patent Document 2.

[0047] Figure 5 yes Figure 4A 3D diagram of the center-of-gravity shifting tube of a fishing bait.

[0048] Figure 6 This is a side cross-sectional view of a representative example of the fishing bait of the present invention.

[0049] Figure 7 This is a cross-sectional view of the central portion of the fishing bait of the present invention cut along the width direction in the length direction.

[0050] Figure 8 This is a perspective view showing a representative example of the structure of the center-of-gravity shifting tube of the present invention (shown by cutting open the side).

[0051] Figure 9 It is contained in Figure 8 Front and side views of the center of gravity of the shifting tube.

[0052] Figure 10 It is a display Figure 7 This is an explanatory diagram showing the position of the center of gravity of the centroid in the cross-sectional view of the centroid-moving tube.

[0053] Figure 11 This is a perspective view showing another example of the configuration of the center-of-gravity shifting tube of the present invention (which is related to...). Figure 8 (The same image shown is cut from the side). Detailed Implementation

[0054] While referring to the attached diagram Figures 6-11 The present invention will be described in detail with respect to the fishing bait and the center of gravity shifting tube.

[0055] Able to refer to Figures 6-10 To understand the overall and internal structure of the fishing bait of the present invention.

[0056] If it is possible to Figure 6 Understood, the fishing bait of the present invention is a fishing bait that, like the fishing bait described in Patent Document 2, has an elongated shape that mimics a small fish, including a bait body 11 having an elongated space 52 inside and a hook mounted on the body. In the internal space 52 of the body, a straight tube-shaped center of gravity shifting tube 41 is fixed, the center of gravity shifting tube 41 accommodates a rod-shaped center of gravity body 42, the center of gravity body 42 has a shape that is symmetrical about the width and can move smoothly in the length direction, but the fishing bait of the present invention is characterized by having the following configuration.

[0057] (1) A straight-tube-shaped center-of-gravity shifting tube is disposed within the interior space of the decoy body. Regarding the center-of-gravity body housed within it, its longitudinal central axis moves to a position below the central axis within the interior space of the decoy body.

[0058] (2) Regarding the above-mentioned centroid, its cross section in the width direction has a shape such as a polygon, a semicircle, or a composite shape such as a combination of polygons and semicircles, with the plane along the maximum diameter of the cross section having a flat top surface.

[0059] Furthermore, on the flat top surface of the aforementioned center of gravity, as long as the portion that becomes the upper side of the top surface does not have a larger mass than the portion that becomes the lower side, it can also have protrusions of any shape.

[0060] Next, the fishing bait and center of gravity shift tube of the present invention will be described in detail. However, the main body (body) of the fishing bait is not significantly different from the main body (body) of the fishing bait described in Patent Document 2. Therefore, the description in Patent Document 2 will be used as the description of the main body (body) of the fishing bait of the present invention.

[0061] As mentioned above, the essential difference between the fishing bait described in Patent Document 2 and the fishing bait of the present invention is the assembly position of the center of gravity shifting tube in the internal space of the bait body and the difference between the shape of the center of gravity shifting tube and the shape of the center of gravity body. Therefore, this point will be explained in detail below.

[0062] Regarding the fishing bait of the present invention, the first feature is that, as Figure 6 , Figure 7 as well as Figure 10 As illustrated, the straight-tube-shaped center-of-gravity shifting tube 41 is configured such that the central axis of the center-of-gravity body 42 moves below the central axis inside the internal space 52 of the decoy body. Here, the central axis of the center-of-gravity body 42 refers to the point where it passes through the intersection of the center position in both the width direction (left-right direction) and the height direction (up-down direction) of the center-of-gravity body's shape. Figure 7 A), and an axis that coincides with the straight line (imaginary line) extending along the length direction of the centroid 42.

[0063] Furthermore, the central axis of the interior space of the decoy body also refers to the intersection point that is both the center of the interior space of the decoy body in the left-right direction and the center of the interior space in the up-down direction. Figure 7 (B), and an axis aligned with a straight line (imaginary line) that extends the internal space of the decoy body along its length. It should be able to... Figure 6 and Figure 7 Clearly understand this characteristic structure. Furthermore, such as... Figure 7 and Figure 8As shown, the center of gravity 42 is typically housed within an elongated, dish-shaped tube 41a in a manner that allows for smooth movement along its length. The upper part of this tube 41a is also covered by an elongated cap. Furthermore, the center of gravity movement tube 41, thus configured, is typically secured by a center of gravity movement tube fixing member (see reference 1) formed in a manner that protrudes inwards towards the bait body. Figure 7 ( ) to fix itself to the bait body.

[0064] Next, in the fishing bait of the present invention, if it is possible to... Figures 7-9 Understood, regarding a centroidal body, the basic shape of its cross-section in the width direction has a polygonal, semi-circular, or a composite shape such as a combination of polygons and semi-circles, with the plane along the maximum diameter of the cross-section having a flat top surface.

[0065] The main body of the fishing bait of the present invention is typically manufactured from a pair of molded bodies obtained by parting molding (cut molding) of resin material. Furthermore, it can be manufactured by integrating the two molded bodies together by methods such as bonding after assembling the center-of-gravity shift tube inside them. Ideally, the center-of-gravity body is made of a metal material such as stainless steel, but it can also be formed from a composite material of metal and resin materials or solely from resin material, depending on preference.

[0066] Figure 7 and Figure 8 The center of gravity shown is a polygonal shape with a trapezoidal cross-section in the width direction as a representative shape, and the lateral width of the top surface is greater than the lateral width of the base surface of the trapezoid. The expression "polygonal" does not exclude polygons with rounded (beveled) corners, as is common in mechanical parts. Regarding the center of gravity used in this invention, the cross-section can also be of other shapes, as long as the plane with the largest diameter along its width direction is a flat top surface. That is, it can be other polygons (quadrilaterals other than trapezoids, polygons larger than quadrilaterals such as pentagons), semicircles, or composite shapes such as combinations of polygons and semicircles.

[0067] The centroid of the present invention, whose cross-section in the width direction is a polygon, a semicircle, or a composite shape such as a combination of polygons and semicircles, with a flat top surface along the plane of the maximum diameter of the cross-section, has the advantage of being easily assembled into the lower part of the interior of a decoy body with a shape that narrows in the lower part and bottom side.

[0068] As described above, the center of gravity body housed in the center-of-gravity shifting tube of the present invention has a polygonal or semi-circular shape in which the lateral width of the top surface is greater than the lateral width of the bottom surface. Protrusions of any shape may also be formed on the flat top surface of this center-of-gravity body, but it is undesirable for the portion of the protrusion forming the upper side of the top surface to have a greater mass than the portion forming the lower side of the top surface. This is because it is necessary to ensure a low center of gravity position for the center-of-gravity body of the center-of-gravity shifting tube of the present invention.

[0069] For example, in such a case Figure 10 When the center of gravity is a circular rod with a circular cross-section (perfect circle shape) as shown by a single-dot dashed line, the position (C) of the center axis of the center of gravity tends to be relatively high, making it difficult to assemble the center of gravity moving tube into the interior space of the decoy at a low position.

[0070] Furthermore, ideally, on the sides and bottom of the sides (corners) of the center of gravity, such as Figures 7-9 As shown, a spherical circulation groove is formed, consisting of two parallel and interconnected grooves. This groove accommodates numerous spheres (ball bearings) side-by-side, allowing the spheres to be cyclically held and moved. Each of these spherical circulation grooves has a closed bottom, configured such that, during the movement of the center of gravity, the spheres in one of the two circulation grooves (the side bottom (corner) side) rotate and circulate within the groove while in contact with the inner circumferential surface of the center of gravity movement tube. Simultaneously, the spheres in the other groove also rotate and circulate.

[0071] The center-of-gravity shifting tube assembled within the internal space of the fishing bait of the present invention accommodates the center of gravity body in a manner that allows it to move smoothly within the tube. The tube body may also be a single, integrally formed tube body with a polygonal or other cross-section, but from the viewpoint of tube body manufacturing, such as Figure 7 and Figure 9 As shown, the preferred tube is composed of a portion that houses and holds the center of gravity and a cover portion.

[0072] exist Figure 11 This image shows one other example of the configuration of the center-of-gravity shifting tube for the fishing bait of the present invention. For example... Figure 11 As shown in the diagram, regarding the center-of-gravity shifting tube 41, as long as the center-of-gravity body 42 housed within it can move smoothly along its length, it is not necessary to assemble it as shown in the diagram. Figures 6-10 The image shows a ball bearing that enables the smooth movement of a body with a shifting center of gravity.

[0073] Symbol Explanation

[0074] 10. Fishing bait

[0075] 11. Main body of the bait

[0076] 13 Fishing Line

[0077] 22 guide shaft

[0078] 23 Linear Bushing

[0079] 41. Center of gravity shifting tube

[0080] 41a pipe body

[0081] 42. Center of gravity

[0082] 43. Sphere (ball bearing)

[0083] 44. Sphere circulation tank.

Claims

1. A fishing bait having an elongated shape mimicking a small fish, comprising a bait body having an elongated space inside and a hook mounted thereon, wherein a center-of-gravity shifting tube, integrally formed as a straight tube in the length direction, is fixed within the space of the bait body, the center-of-gravity shifting tube accommodating a rod-shaped center-of-gravity body having a shape symmetrical about left and right along the width direction and capable of smooth movement in the length direction, the fishing bait having the following characteristics: (1) Regarding the center-of-gravity shifting tube, the center-of-gravity body housed within it is positioned within the interior space of the decoy body such that it moves along its length at a position below the central axis within the interior space of the decoy body. (2) Regarding the center of gravity, its cross-section in the width direction is symmetrical in the width direction, and it has a trapezoidal shape in which the lateral width of the top side of the small fish is greater than the lateral width of the bottom side of the small fish. It also has a pair of spherical circulation grooves. Each of the two spherical circulation grooves consists of two grooves that are arranged in parallel and connected to each other. The spherical circulation grooves are filled with spheres in a circulating manner. One side of each spherical circulation groove is located on the opposite non-parallel sides of the trapezoid, and the other side of each spherical circulation groove is located at the corner of each non-parallel side and the bottom. It does not have a spherical circulation groove other than the aforementioned pair of spherical circulation grooves. As the center of gravity moves, the spheres circulate within the sphere circulation grooves in a state of contact with the inner circumferential surface of the center of gravity moving tube in the groove on the other side of each sphere circulation groove.

2. A center-of-gravity shifting tube, comprising a tube body and a rod-shaped center-of-gravity body having a shape symmetrical about left and right along the width direction, which is inserted into the inner side of the tube body in a manner capable of moving along the length direction of the tube body, and having an overall straight tube shape along the length direction, characterized in that, Regarding the aforementioned center of gravity body, its cross-section in the width direction is symmetrical along the width direction, having a trapezoidal shape where the lateral width of the top surface is greater than that of the bottom surface, and possessing a pair of spherical circulation grooves. Each of these spherical circulation grooves consists of two grooves arranged parallel to each other and interconnected. These spherical circulation grooves are filled with spheres in a circulating manner. One side of each spherical circulation groove is located on each of the opposite non-parallel sides of the trapezoid, and the other side of each spherical circulation groove is located at the corner of each non-parallel side and the bottom surface. It does not have a spherical circulation groove other than the aforementioned pair of spherical circulation grooves. As the center of gravity moves, the spheres circulate within the sphere circulation grooves on the other side of each sphere circulation groove, in a state of contact with the inner circumferential surface of the tube.

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