Nut loosening preventive device

Abstract

To provide a loosening prevention device capable of generating an excellent loosening prevention action for an existing general nut.SOLUTION: A nut loosening prevention device 1 includes a cover member 2 and a locking nut member 3. The cover member 2 includes a cylindrical part 21 externally fitted to a nut N fastened to a bolt B and a flange part 22 that engages with the top face of the nut N. The locking nut member 3 includes a screw hole 31 screwed with a screw shaft of the bolt B above the nut N. The flange part 22 is provided with a through-hole 23 into which the bolt B is inserted. The locking nut member 3 includes a convex part 32 that engages with the through-hole 23. The convex part 32 is eccentric with respect to the through-hole 23 so that the outer periphery of the convex part 32 interferes with the inner periphery of the through-hole 23 in a part in a circumferential direction, and pressing force orthogonal to an axial direction is generated in the nut N.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a device for preventing a nut from loosening when fastened to a bolt. [Background technology]

[0002] The applicant of the present application has been developing a hard lock nut ("Hard Lock" is a trademark of the applicant of the present application) that is an anti-loosening nut that exhibits a high level of anti-loosening function, and has disclosed these in, for example, Patent Documents 1 to 4 described below.

[0003] This hard lock nut is composed of a lower nut having a threaded hole that screws onto a screw shaft, and an upper nut having a threaded hole that screws onto the screw shaft.

[0004] Either the lower nut or the upper nut is provided with a convex portion in the shape of a truncated cone that protrudes axially toward the other nut. The convex portion has a tapered outer peripheral surface with a predetermined taper angle that gradually decreases in diameter toward the tip side. The screw hole passes through the convex portion along the axial direction. A nut with a convex portion is called a "convex nut."

[0005] The other nut has a recess into which the protrusion fits. The recess has a tapered inner circumferential surface with a taper angle that matches the taper angle of the outer circumferential surface of the protrusion, preferably the same taper angle. The screw hole of the other nut opens to the bottom surface of the recess. A nut having a recess is called a "concave nut."

[0006] The Hardlock Nut has an eccentric fit between a convex portion and a concave portion, which creates a stress state just as if a wedge had been driven between the outer periphery of the screw shaft and the inner periphery of the screw hole in the nut, and this wedge action provides a powerful anti-loosening effect.

[0007] The eccentric fit between the convex portion and the concave portion is achieved by forming the outer peripheral surface of the convex portion eccentrically with respect to the screw hole of the convex nut, or by forming the inner peripheral surface of the concave portion eccentrically with respect to the screw hole of the concave nut. When the outer peripheral surface of the convex portion is eccentric, the inner peripheral surface of the concave portion and the screw hole of the concave nut are made concentric. On the other hand, when the inner peripheral surface of the concave portion is eccentric, the outer peripheral surface of the convex portion and the screw hole of the convex nut are made concentric.

[0008] In a Hardlock Nut, when the convex and concave portions of the upper and lower nuts are screwed onto the screw shaft, they are eccentrically fitted together, and the outer peripheral surface of the convex portion and the inner peripheral surface of the concave portion interfere with each other along part of the circumferential direction so that a pressing force is generated in each of the upper and lower nuts in the eccentric direction. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent No. 6762591 [Patent Document 2] JP 2016-125622 A [Patent Document 3] JP 2016-133136 A [Patent Document 4] JP 2002-195236 A [Patent Document 5] JP 2011-174600 A Summary of the Invention [Problem to be solved by the invention]

[0010] Replacing existing standard nuts with Hardlock Nuts can provide excellent anti-loosening effects, but in cases where there are a huge number of existing nuts, the work of removing the existing nuts is time-consuming and the total work time is long, so they have sometimes been replaced with simple anti-loosening clips such as those shown in JP 2011-174600 A (Patent Document 5). However, users are demanding a locking device that can apply the principles of the hard lock nut to prevent loosening of existing standard nuts. [Means for solving the problem]

[0011] The nut locking device of the present invention locks a nut fastened to a bolt from loosening, and includes a cover member having a cylindrical portion fitted onto the nut and a flange portion engaging with an upper surface of the nut, and a locking nut member having a screw hole that screws onto the screw shaft of the bolt above the nut. A through hole through which the bolt is inserted is provided in the flange portion. The locking nut member has a protrusion that fits into the through hole. The protrusion is eccentric with respect to the through hole so that an outer periphery of the protrusion and an inner periphery of the through hole interfere with each other at a portion in the circumferential direction, generating a pressing force on the nut perpendicular to the axial direction.

[0012] According to the nut loosening prevention device of the present invention, when a cover member is fitted onto an existing nut (general nut) fastened to a bolt and a lock nut member is fastened to the bolt above the nut, the outer periphery of the protrusion and the inner periphery of the through hole interfere with each other in a circumferential portion, and the cover member is pressed in a direction perpendicular to the axial direction, and the inner periphery of the cover member and the outer periphery of the nut come into strong contact with each other in a portion diametrically opposed to the circumferential portion, and a pressing force perpendicular to the axial direction is generated on the nut. In addition, due to the interference, a pressing force is generated on the lock nut member that is opposite to the pressing force generated on the nut. The pressing force generated by the wedge action on the nut and the lock nut member provides an excellent locking effect on the nut and the lock nut member.

[0013] In the nut loosening prevention device according to the present invention, the screw hole of the lock nut member may be formed to open downward, and the lock nut may have a top portion that closes the upper end of the screw hole. This can prevent rainwater or the like from entering the screw hole, and can prevent corrosion of the screw hole and the bolt.

[0014] The outer peripheral surface of the locking nut member may be cylindrical or frusto-conical, which prevents the locking nut member from being tampered with by a general spanner or box wrench, and allows the locking nut member to be fastened by a special tool that is compatible with the outer peripheral surface shape of the locking nut member.

[0015] The outer circumferential surface of the cover member may be cylindrical or frusto-conical, which can prevent the nut from being loosened tamperingly with a common spanner or box wrench.

[0016] The outer peripheral surface of the protrusion and the inner peripheral surface of the through hole may be configured in a truncated cone shape with a diameter gradually decreasing downward. By tapering the protrusion and the through hole in this manner, a large pressing force can be generated on the nut in accordance with the fastening force of the lock nut member, and a larger wedge action can be generated.

[0017] The inner peripheral surface of the through hole may be concentric with the inner peripheral surface of the cylindrical portion, and the outer peripheral surface of the protrusion may be eccentric with respect to the screw hole. Alternatively, the inner peripheral surface of the through hole may be eccentric with respect to the inner peripheral surface of the cylindrical portion, and the outer peripheral surface of the protrusion may be concentric with the screw hole. The cover member and the locking nut member may be made of a hard material, preferably a metal such as a steel material having a strength equal to or greater than that of the existing nut. Effect of the Invention

[0018] According to the present invention, a nut loosening prevention device can be provided that can provide an excellent loosening prevention effect for existing general nuts. [Brief description of the drawings]

[0019] [Figure 1] 1 is a half-section longitudinal sectional view showing a state before installation of a nut loosening prevention device according to a first embodiment of the present invention. [Diagram 2] 1 is a vertical cross-sectional view of a nut loosening prevention device according to a first embodiment in an attached state. FIG. [Diagram 3] FIG. 4 is a perspective view of the anti-loosening device in an attached state. [Figure 4] FIG. 6 is a vertical cross-sectional view showing a state before installation of a nut loosening prevention device according to a second embodiment of the present invention. [Diagram 5] FIG. 4 is a vertical cross-sectional view of the anti-loosening device in an installed state. [Figure 6] FIG. 4 is a perspective view showing an embodiment of a cover member of the locking device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] 1 to 3 show a nut loosening prevention device 1 according to a first embodiment of the present invention. The loosening prevention device 1 prevents a nut N fastened to a bolt B and the nut N from loosening by being attached to the bolt B.

[0021] The locking device 1 includes a cover member 2 that is fitted onto a nut N, and a locking nut member 3 that is screwed onto a bolt B above the nut N.

[0022] The cover member 2 has a tubular portion 21 that fits around the nut N and a flange portion 22 that engages with the upper surface of the nut N. The tubular portion 21 is cylindrical, and its inner diameter is slightly larger than the maximum diameter portion of the nut N (i.e., the diameter of the corner portion of the hexagonal nut). The flange portion 22 may extend radially inward from the upper end of the tubular portion 21. The flange portion 22 is provided with a through hole 23 through which the bolt B is inserted. The through hole 23 has an inner diameter larger than the outer diameter of the bolt B, and is configured so that the protrusion 32 fits between the inner circumference of the through hole 23 and the outer circumference of the screw shaft of the bolt B. The inner peripheral surface of the through hole 23 is formed in a truncated cone shape that gradually becomes smaller in diameter as it approaches the bottom. The axis of the inner peripheral surface of the through hole 23 is arranged concentrically with the axis of the inner peripheral surface of the tubular portion 21.

[0023] The locking nut member 3 has a threaded hole 31 that screws onto the threaded shaft of the bolt B above the nut B, and a protrusion 32 that fits into the through hole 23. The threaded hole 31 is provided with an opening downward, and the upper end of the threaded hole 31 is closed by a top 33. The outer circumferential surface of the locking nut member 3 is formed in a truncated cone shape that gradually decreases in diameter toward the top. The protrusion 32 is configured in a truncated cone shape that gradually decreases in diameter toward the bottom.

[0024] The protrusion 32 of the locking nut member 3 screwed onto the bolt B is eccentric by a predetermined eccentricity amount d with respect to the through hole 23 of the cover member 2 fitted onto the outside of the nut N so that the outer circumferential surface of the protrusion 32 and the inner circumferential surface of the through hole 23 interfere with each other in a portion of the circumferential direction (the left side of the bolt B in FIG. 2 ), generating a pressing force perpendicular to the axial direction on the nut N. Note that the above configuration may be realized by making the protrusion 32 eccentric with respect to the screw hole 31, or by making the through hole 23 eccentric with respect to the cylindrical portion 21.

[0025] According to the nut loosening prevention device 1 of the first embodiment, by fitting the cover member 2 onto an existing general nut N fastened to a bolt B and fastening the lock nut member 3 to the bolt B above the nut N, a wedge action is generated by the eccentric fit between the through hole 23 of the cover member 2 and the convex portion of the lock nut member 3, and large opposing horizontal pressing forces are generated on the nut N and the lock nut member 3, thereby achieving an excellent loosening prevention function. Furthermore, after the installation of the loosening prevention device 1, the entire structure is covered with a circumferential surface or a conical surface as shown in Fig. 3, and it becomes impossible to use a general spanner or wrench, so that it is possible to prevent the nut N from being loosened by tampering or the like.

[0026] 4 to 6 show a nut loosening prevention device 1' according to a second embodiment of the present invention. The loosening prevention device 1' prevents a nut N fastened to a bolt B from loosening by being attached to the bolt B.

[0027] The locking device 1' comprises a cover member 2' that is fitted onto the nut N, and a locking nut member 3' that is screwed onto the bolt B above the nut N.

[0028] The cover member 2' has a cylindrical portion 21' that fits around the nut N and a flange portion 22' that engages with the upper surface of the nut N. The cylindrical portion 21' is hexagonal, and the inner peripheral surface shape is slightly larger than the outer peripheral surface shape of the nut N. The cover member 2' of this embodiment can be formed by bending the upper end of a thin-walled cylinder using a press or the like as shown in FIG. 6. The flange portion 22' extends radially inward from the upper end of the cylindrical portion 21', and extends downward at its radially inner end to form a through hole 23' through which the bolt B is inserted. The through hole 23' has an inner diameter larger than the outer diameter of the bolt B, and is configured so that the protrusion 32' fits between the inner circumference of the through hole 23' and the outer circumference of the screw shaft of the bolt B. The inner peripheral surface of the through hole 23' is formed in a truncated cone shape that gradually becomes smaller as it approaches the bottom. The axis of the inner peripheral surface of the through hole 23' is arranged concentrically with the axis of the inner peripheral surface of the cylindrical portion 21'.

[0029] The locking nut member 3' has a threaded hole 31' that screws onto the threaded shaft of the bolt B above the nut B, and a protrusion 32' that fits into the through hole 23'. The threaded hole 31' is provided penetrating in the vertical direction. The outer circumferential surface of the locking nut member 3' is formed into a hexagonal shape in a plan view. The protrusion 32' is configured in a truncated cone shape that gradually becomes smaller in diameter as it extends downward.

[0030] The convex portion 32' of the locking nut member 3' screwed onto the bolt B is eccentric by a predetermined eccentricity amount d with respect to the through hole 23' of the cover member 2' fitted onto the nut N so that the outer peripheral surface of the convex portion 32' and the inner peripheral surface of the through hole 23' interfere with each other in a part of the circumferential direction (the left side of the bolt B in Figure 5), generating a pressing force on the nut N perpendicular to the axial direction.

[0031] A dome-shaped closing portion 4' is integrally provided at the top of the locking nut member 3'. By providing the closing portion 4' in a dome shape in this way, even if the existing bolt protrudes somewhat greatly, the locking nut member 3' can be screwed onto the bolt while receiving the bolt protrusion. The screw hole 31' can be provided with an upward opening, and a closing member separate from the locking nut member 3' can be fitted from above into the screw hole 31' of the locking nut member 3' to close the screw hole 31'. Such a closing member 4' may be made of an elastic material such as rubber, or may be made of a hard material such as metal or plastic.

[0032] The nut loosening prevention device 1' according to the second embodiment can also exhibit the same excellent loosening prevention function as the first embodiment.

[0033] The present invention is not limited to the above embodiment, and the design can be modified as appropriate. For example, the outer peripheral surface of the protrusion and the inner peripheral surface of the through hole may be formed in a right cylindrical shape. In the above embodiment, the outer peripheral surface of the protrusion is eccentric with respect to the screw hole, and the through hole and the cylindrical portion are arranged concentrically, but the protrusion and the screw hole may be arranged concentrically, and the inner peripheral surface of the through hole may be eccentric with respect to the inner peripheral surface of the cylindrical portion. [Explanation of symbols]

[0034] 1 Nut locking device 2 Cover material 21 Cylindrical part 22 Flange 23 Through hole 3 Locking nut member 31 Screw hole 32 Convex 33 Occlusion

Claims

1. A device for preventing loosening of a nut fastened to a bolt, comprising: a cover member having a cylindrical portion fitted onto the nut and a flange portion engaged with an upper surface of the nut; and a lock nut member having a screw hole screwed onto a screw shaft of the bolt above the nut, The flange portion is provided with a through hole through which the bolt is inserted, The locking nut member has a protrusion that fits into the through hole, The protrusion is eccentric with respect to the through hole so that an outer periphery of the protrusion and an inner periphery of the through hole interfere with each other in a circumferential portion, thereby generating a pressing force perpendicular to the axial direction on the nut. A device to prevent nuts from loosening.

2. The nut loosening prevention device according to claim 1, A nut loosening prevention device, wherein the screw hole of the locking nut member is formed to open downward, and the locking nut has a top portion closing an upper end of the screw hole.

3. The nut loosening prevention device according to claim 1, A nut loosening prevention device, wherein the outer peripheral surface of the locking nut member is cylindrical or frusto-conical.

4. The nut loosening prevention device according to claim 1, 2 or 3, A nut loosening prevention device, wherein the outer peripheral surface of the cover member is cylindrical or frusto-conical.

5. The nut loosening prevention device according to claim 1, A nut loosening prevention device, wherein an outer peripheral surface of the convex portion and an inner peripheral surface of the through hole are configured to have a truncated cone shape whose diameter gradually decreases toward the bottom.

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