GB2463894A

GB2463894A - Locking washer

Info

Publication number: GB2463894A
Application number: GB0817718A
Authority: GB
Inventors: Gal Wollach; Michael Zettner
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-09-29
Filing date: 2008-09-29
Publication date: 2010-03-31
Anticipated expiration: 2028-09-29
Also published as: GB0817718D0; GB2463894B

Abstract

A locking washer 22 is securable between a fastener 20 and a surface 24. The locking washer 22 includes a locking mechanism 29, 30, 31 for securing the fastener 20 at a predetermined rotational angle and a positioning means for securing the position of the locking washer 22 relative to the fastener 20.

Description

LOCKING WASHER

FIELD OF THE INVENTION

s The present invention relates in general to locking washers. In more particular the present invention relates to locking washers and self locking threaded fasteners.

BACKGROUND OF THE INVENTION

io Locking the rotational motion of threaded fastener, such that they will not be unintentionally opened called for various solutions. A variety of solutions iii which the threaded fasteners are adapted and arranged for such locking are known. Exemplary are bolts and matching nuts in accordance with DIN 935, in which a pin inserted through a bore structured through the bolt provides such locking when is engaged with cogs of the nut. Locking washers (LW), which are among such solutions, are common in the marketplace. Exemplary is a LW in accordance with DIN 432. Reference is now made to Figs IA -I B in which LW according to DIN 432 is shown locking the rotational motion of nut 12 relative to bolt 14 (same numbers designate the same parts in Figs IA, lB.) Peg 16 provides for avoiding any rotational motion of LW 10 relative to surface 17. Recess 18 disposed at the rim of LW 10 provides for locking such rotational motion by any of its side walls when is respectively engaged with peg 16.

Any locking washer providing for locking the rotational motion of threaded fasteners (nuts, screws and/or bolts), the locking action of which can be such arranged that the magnitude of the force exerted by the locked fastener onto the surface to which it is attached, is of a level within a desired range; the magnitude of the torque required for closing said fastener is confined by respective desired limits; that the locking action is automatically activated while rotating the respective fastener in the closing direction, and does not require special tooling for such rotating in a closing direction, is beneficial

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1A is a sectional view of a locking washer (LW) according to DIN 432 while it locks the rotational motion of a nut screwed onto a bolt; Fig. 16 is an elevational view of the LW shown in Fig. 1; Fig. 2 is an isometric view of a LW according to an embodiment of the present invention while is locking the rotational motion of a nut screwed onto a bolt; Fig 3A is an isometric view of a bolt adapted to be rotationally locked by means of a LW according to an embodiment of the present invention; Fig. 3B is an isometric view of a LW according to a preferred embodiment of the present invention Fig. 3C is a sectional view of the LW shown in Fig. 3B placed at a rim of an aperture of a threaded bore; Fig. 3D is an isometric view of the bolt shown in Fig. 3A prior to its being rotationally locked by means of the LW shown in Fig. 3C; Fig. 3E is an isometric view of the bolt and LW shown in Fig. 3D at a locked position; Fig. 4 is an isometric view of a LW according to an embodiment of the present invention;

DETAILED DESCRIPTION OF THE PRESENT INVENTION

In accordance with the present invention a system and method for locking the rotational motion of threaded fasteners (nuts, screws and/or bolts) is provided. A locking washer (LW) of the invention has one or more locking mechanisms and at least one positioning means. A locking mechanism of the LW is adapted and arranged to automatically interlock with a respective engaging member that is placed either at a face of the threaded fastener or at the surface onto which the threaded fastener is to be attached. Such interlocking is automatically activated at the instant in which the threaded fastener accomplishes a rotation about its axis the magnitude of which equals a predefined rotational angle. In a case in which the engaging member is placed at a face of the threaded fastener, the automatic interlocking provides for blocking any rotational motion of the threaded fastener relative to the LW. In a case in which the engaging member is placed on the surface to which the LW is is attached, the automatic interlocking blocks the rotational motion of the LW relative to this surface. A positioning means of a LW of the invention is adapted and arranged to be engaged with a respective engager, such that the rotational motion of the LW relative to the engager is securely locked. The engager is respectively disposed either at the surface onto which the threaded fastener is to be attached, or at a face of the respective threaded fastener. In a case in which the engager is placed on a face of the threaded fastener any rotation of the LW relative to the fastener is avoided when a positioning means and the respective engager are mutually engaged. Similarly in a case that the engager is placed on the surface to which the LW is to be attached the LW cannot rotate relative to this surface when the respective positioning means and the engager are mutually engaged. Therefore either an engaging member is disposed at a face of the threaded fastener and an engager is disposed at the surface to which the LW is to be attached to, or vice versa, the engaging member is disposed at the surface whereas the engager is disposed at a face of the threaded fastener. The locking mechanisms employed according to the invention can be any of the type of snap locks as known, in which a resilient member is forced to open and released to close and/or vice versa.

Complementary tools for unlocking a rotationally locked treaded fastener in accordance with the present invention are further provided.

As the spatial orientation of a LW is arbitrary namely it can be oriented in any direction in space. The directions specified in the description below normally refer to the neighboring components to a component considered. For example a LW that interleaves between a threaded fastener and the surface which it is attached to has one face that faces the threaded fastener whereas the other face touches the surface. Normally the body of a LW of the invention is circular. Therefore dimensions measured along the radii are referred hereinafter as widths; lateral or tangential dimensions (that are normally measured along circular arcs) are referred as lengths, whereas dimensions axially measured along lines that are perpendicular to the faces of a LW are referred hereinafter as thicknesses or depths.

Reference is now made to Fig. 2 in which nut 20 that is adapted and arranged according to the present invention to be rotationally locked by means of LW 22 is shown at a closed position. LW 22 that is in accordance with a preferred embodiment of the present invention interleaves between nut 20 and surface 24 to which it is attached. Nut 20 has been continuously rotated about its axis, which is the same axis of bolt 26, in a closing direction (shown by curved arrow 27). When the rotational angle by which nut 20 is rotated exceeds a given threshold, engaging member 28 of nut 20 is released off tongue 29, thereby locking of the rotational motion of nut 20 is accomplished. Tongue 29 as well as sidewall 30 and niche 31, are integral components of the locking mechanism embedded according to the invention in LW 22. The threshold limiting the rotational angle by which the threaded fastener is rotated is the respective rotational angle in which the locking mechanism embedded in the LW is locked. This threshold is derived in consideration with the magnitude of the force to be exerted by the threaded fastener into the connection accomplished by means of the pair nut 20 and bolt 26, as well as by the maximal level of torque to be exerted on the threaded fastener for its closing.

Embodiment variants in which a recess implements the engaging member whereas a matching protrusion disposed at the free end of the tongue substitute niche 31 are in accordance with the present invention.

For better describing the features of the present invention another exemplary case in which the threaded fastener considered is a bolt, is hereby described with reference to Figs 3A -3E. In Fig. 3A an isometric view of bolt 36 is shown. Bolt 36 is provided with engaging member 38 the geometrical shape of which according to a preferred embodiment of the present invention is cubical. In Fig. 3B an isometric view of a LW according to a preferred embodiment of the present invention is shown. Body 40 of LW 42 encloses central bore 43 that provides LW 42 to be placed circumferential with the threaded fastener considered. Tongue 44 occupies most of the inner space enclosed by slot 45 that spans across central angIe 46 (the vertex of which disposed on the axis of LW 42, not shown). Tongue 44 is elastic due to its relatively small thickness. Such elasticity provides for bending tongue 44 when is stressed parallelly with the axis of LW 42 and for springing back to its former linear or planar form when is released off. Such stress is exerted by the engaging member when is slidingly rotated along tongue 44. One sidewall of tongue 44 is spaced apart from the lateral wall of slot 45 by spacing 47. One end of tongue 44 is attached, or preferably integrally connected, to one sidewall of slot 45. The locking mechanism of LW 42 consists of tongue 44 and niche 48 housed in slot 45. Niche 48 disposed between the free end of tongue 44 and sidewall 50 conforms to the lateral dimensions of the engaging member of the threaded fastener considered. The angle of introduction is the rotational angle in which the threaded fastener has to be rotated such that the engaging member starts touching tongue 44 as close as possible to its connected end The magnitude of the angle of introduction is defined by the orientation of the LW relative to the threads associated with the threaded fastener considered.

This angle can be increased or decreased by respectively rotating the LW about its axis in the closing direction or vice versa. The magnitude of the angle of introduction, the level by which the engaging member extends off the face of the threaded fastener (the same face that faces LW 42) towards LW 42; the lateral dimensions of this engaging member; the length of tongue 44; the length of niche 48; the pitch of the threads of the threaded fastener considered; the materials from which the LW as well as both the male and female threads are made, as well as the material from which the body a surface of which is the surface to which the LW is to be attached, uniquely define the level of the force to be exerted by the threaded fastener on LW 42 as well as the magnitude of the torque required for rotating the fastener into a closed position. The rotational angle its magnitude equals the sum of the angle of introduction and the central angle spanned by the tongue is the respective threshold beyond which the threaded fastener has to be rotated into a close position. The magnitude of this angle is uniquely related to the magnitude of the torque for closing the threaded fastener and to the force exerted onto the LW. Depth 51, which is the maximal distance along which the free end of tongue 44 can move when is pressed by the engaging member is selected in consideration with the length of tongue 44 and the pitch of the threaded fastener Is In Fig. 3C LW 54 which is similar to the LW described above is shown placed on top of surface 55 circumferential to the aperture of bore 56. The threads of bore 56 conform with the threads of the bolt considered. Positioning means 57 the geometrical shape of which is cubical extends into an engager implemented by a recess disposed at the rim of the aperture of bore 56. Both positioning means 57 and the engager provide for avoiding any rotation of LW 54 about its axis when respective torques are exerted onto LW 54 while bringing the bolt into the closed position. The site in which the engager is axially located relative to the threads is selected in consideration with a specified point positioned relative to the threads in which the engaging member first touches the surface of LW 54 while is rotated at a closing direction, such that it touches the tongue as close as possible to its connected end. Embodiment variants in which a niche implements the positioning means of a LW whereas a matching protrusion implements the engager are in accordance with the present invention. In Figs 3D -3E two stages, such as by respective snapshots taken at Iwo different points in time, of the process of the locking activity effected by the locking mechanism according to a preferred embodiment of the present invention are respectively shown. (The same parts are designated by the same numbers in Figs 3D, 3E.) The locking mechanism of LW 60 is activated at the rotational angle that equals the angle of introduction. The LW can not rotate as it is fixed to the surface by a positioning means (not shown). Engaging member 62 starts pressing against tongue 64 while threaded fastener 65 is continuously rotated by the angle of introduction at the closing direction, shown by curved arrow 66. In Fig. 3D tongue 64 is shown bended almost to its maximal extent in the direction shown by arrow 67. The point in time in which engaging member 62 stops pressing against tongue 44 while is being continuously rotated at the same closing direction, tongue 44 is sprung back to the same non-stressed io position at the same level in which it was positioned before the instant in which the locking mechanism is activated, as shown in Fig. 4E. Locking is therefore accompanied by a "click" signaling the user accordingly. The rotational motion of engaging member 62 as well as of the threaded fastener in the direction of arrow 66 is blocked by sidewall 68 of the niche of the locking mechanism of LW 60. The free end of tongue 64 blocks any rotational motion of threaded fastener in the opposite direction. In turn the rotational motion of threaded fastener is locked, unless the level of the free end of tongue 64 is forced back to its extreme bended state which occurred immediately prior to the closed stage.

A LW according to an embodiment of the present invention that provides a user with an extended tolerance in the level of the torque for closing the threaded fastener is provided with two or three different locking mechanisms.

The tongue of a locking mechanism need not extend beyond the rim of the threaded fastener. Such LW and the complementary threaded fastener may provide for closing an enclosure such that a tamper evident closed enclosure is provided. Reference is now made to Fig. 4 in which a sectional view of tamper evident screw 90 and LW 92 according to an embodiment of the present invention are shown while being at a closed position. The outline of the missing portion of the face of screw 90 that faces LW 92 is presented by dashed line 94. Screw 90 and LW 92 are attached to the surface 95 of an enclosure, not shown. Engaging member 96 that protrudes off the face confined by dashed lines 94 is enclosed within the niche disposed between the free end of the tongue of LW 92 and the respective sidewall of the slot housing this locking mechanism. Circumferential sidewall 97 extends off the face of screw 90 skirts LW 92 such that the tongue of LW 92 cannot be accessed from the outside when screw 90 is at closed position. Alternatively, the slot housing the locking mechanism can be structured circumferential to the bore of the LW, such that the body of the LW blocks any access towards the bendable tongue.

A breakable or rupturable tongue and a window disposed at this sidewall at a site facing the tongue provide for visually inspecting whether an unauthorized opening of the threaded fastener, hence damaging the LW has been accomplished. Furthermore, any segment of the body of a LW of the present invention can be such geometrically shaped and/or sized, or made of such material that makes the LW breakable or rupturable at a site disposed within this segment. Such LW provides for tamper evident connection as any opening of the respective threaded fastener involves breaking or tearing off the respective LW. Optionally, a bore having two apertures, is structured through the screw head such that its inner aperture faces the tongue at a site adjacent to its free end; the other aperture is located at the external face of the head of the screw. This aperture is typically sealed off with a tamper evident seal as known. The seal does not interfere when rotating the screw such as by a screwdriver or hexagonal key. However for opening and releasing off screw 90 first the seal has to be removed such that the screw will be rotationally unlocked. Unlocking is accomplished by pressing the free end of the tongue to bend it until its end lies beyond the level of the extreme face of the engaging member. A slender shaft the cross section of which conforms with the cross section of the bore provides for unlocking the rotationally locked screw.

Following pressing the tongue beyond the level of the free face of the engaging member the screw is rotated slightly in the opening direction. By such rotation the free end of the bended tongue is supported by the free face of the engaging member. From this stage on, the engaging member can be further slidingly rotated along the face of the tongue such that the screw can be continuously rotated in the opening direction.

Any common tool, that is normally used for rotating a threaded fastener such as a screw, bolt or nut; that is normally provided with a key adapted and arranged for rotating the threaded fastener considered; that is further provided with a lever laterally shifted off its main axis, such that it avoids the periphery of the threaded fastener and yet provides for pressing against the periphery of the tongue extending beyond the edge of the threaded fastener considered, can be employed for opening and releasing off such rotationally locked threaded fastener. Obviously, a lever that can be introduced through a bore structured in the body of the threaded fastener such that its apertures face the tongue of the LW is in accordance with the present invention.

Claims

CLAIMS1. A locking washer (LW) for locking the rotational motion of a threaded fastener, wherein said LW has a body in which a bore is structured, and wherein said threaded fastener is rotatably movable from an open position into a closed position and vice versa, and wherein said LW provides for interleaving between a face of said threaded fastener and a surface onto which said threaded fastener is to be attached, said LW comprising * at least one locking mechanism adapted and arranged to automatically interlock at a predefined rotational angle; at least one positioning means for securing the position of said LW relative to a predefined point axially positioned relative to a thread associated with said threaded fastener and securing the Is orientation of said LW at a given rotational angle relative to an axis of said threaded fastener.
2. A LW as in claim 1, wherein said predefined rotational angle is selected in consideration with the magnitude of the torque providing for rotating said threaded fastener into said closed position.
3. A LW as in claim 1, wherein said predefined rotational angle is selected in consideration with the magnitude of the force to be exerted by said threaded fastener onto said LW.
4. A LW as in claim 1, wherein said at least one locking mechanism conforms to the geometrical shape of a portion of at least one engaging member, and wherein said at least one positioning means conforms to the geometrical shape of a portion of at least one engager.
5. A LW as in claim 4, wherein said at least one locking mechanism comprises * a slot disposed circumferential to any member selected from a group of members consisting of said body and said bore; * an elongated and bendable tongue one end of which connected to a first end of said slot.
6. A LW as in claim 5, wherein said at least one locking mechanism further comprises a niche disposed between the free end of said elongated bendable tongue and the second end of said slot, and wherein said niche accommodated to enclose at least a portion of said engaging member.
7. A LW as in claim 5, wherein said at least one locking mechanism further comprises a protrusion extending off the free end of said elongated bendable tongue, and wherein said engaging member comprises a recess accommodated to enclose at least a portion of said protrusion.
8. A LW as in claim 4, wherein said engaging member positioned on said face, and wherein said engager positioned on said surface.
9. A LW as in claim 4, wherein said engaging member positioned on said surface, and wherein said engager positioned on said face.
10. A LW as in claim 5, wherein a portion of said tongue extends beyond the rim of said threaded fastener.
11. A LW as in claim 1, wherein a portion of the body of said LW is characterized by any feature selected from a group of features consisting of breakable and rupturable.
12. A LW as in claim 5, wherein said elongated and bendable tongue is characterized by any feature selected from a group of features consisting of breakable and rupturable.
13. A method for locking the rotational motion of a threaded fastener, wherein said threaded fastener is movable from an open position into a closed position by rotating in a closing direction, and wherein said threaded fastener comprises a face directed towards a locking washer (LW), and wherein said LW interleaves between said threaded fastener and a surface to which said threaded fastener is to be attached, said method comprising a. securing the axial position and orientation of said LW by means of at least one positioning means embedded in said LW, wherein said axial position selected relative to a thread associated with said threaded fastener, and wherein said orientation selected relative to the axis of said threaded fastener; b. automatically interlocking at least one locking mechanism embedded in said LW by rotating said threaded fastener in said closing direction by a rotational angle which is not smaller compared to a predefined threshold.
14. A method as in claim 13, wherein said threshold selected in consideration with the magnitude of a torque providing for said rotating.
15. A method as in claim 13, wherein said threshold selected in consideration with the level of force to be exerted by said threaded fastener onto said LW.
16. A method as in claim 13, wherein said at least one locking mechanism comprises * a slot disposed circumferential to said body; * an elongated and bendable tongue one end of which connected to a first end of said slot.
17. A method as in claim 16, wherein said elongated and bendable tongue is bended by rotating said threaded fastener at a rotational angie the magnitude of which does not exceed said threshold, and wherein said tongue is sprung when said rotational angle exceeds s said threshold in a direction in which said tongue is less stressed, and wherein said springing effects said interlocking.Amendment to the claims have been filed as followsCLAIMS1. A locking washer (LW) for locking the rotational motion of a threaded fastener having a body in which a bore is structured, wherein said threaded fastener has a face which is the fastener face, and wherein said threaded fastener is movable in a closing direction, and wherein said LW further comprises at least one positioning means for securing the orientation of said LW relative to the axis of said threaded fastener, and wherein said LW interleaves between said fastener face and the face of an object onto which said threaded fastener is to be attached, which is the object face, said LW comprising at least one locking mechanism wherein said locking mechanism comprises a locking member and a resilient member, and wherein said locking member adapted and arranged to automatically is interlock with a respective engaging member when said threaded fastener is rotated by a predefined rotational angle **.. * * * *. * **S*2. A LW as in claim 1, wherein the face selected from said group of faces is the first face, and wherein at least a portion of said at least one positioning means engaged with an engager associated with the * ** * * * second face of said group of faces. S. * S * * S *3. A LW as in claim 1, wherein said at least one ocking mechanism comprises a slot disposed circumferential to any member selected from a group of members consisting of said body and said bore, and wherein an elongated and bendable tongue one end of which connected to a first end of said slot implements said resilient member.4. A LW as in claim 3, wherein a niche positioned between the free end of said elongated and bendable tongue and the second end of said slot implements said locking member.5. A LW as in claim 3, wherein a protrusion extending off the free end of said elongated and bendable tongue implements said locking member.6. A LW as in claim 3, wherein a portion of said tongue extends beyond the rim of said fastener face.7. A LW as in claim 3, wherein a member of a group of members consisting of a portion of said body of said LW and said elongated and bendable tongue is characterized by any feature selected from a : **.* group of features consisting of breakable and rupturable. S...: .. 8. A method for locking the rotational motion of a threaded fastener, *..j wherein said threaded fastener is movable in a closing direction, and wherein said threaded fastener comprises a face, which is the fastener face, directed towards a locking washer (LW), and wherein said LW interleaves between said fastener face and a face of an object to which said threaded fastener is to be attached, which is the object face, and wherein said LW comprises a body in which a bore is structured, and wherein said LW further comprises at least one positioning means and at least one locking mechanism, and wherein said at least one locking mechanism comprises a locking member and a resilient member, said method comprising a. orienting said LW at a predefined orientation relative to the axis of said threaded fastener by engaging said at least one positioning means with an engager associated with a face which is the first face and which is selected from a group of faces consisting of said fastener face and said object face; b. interlocking said locking member of said at least one locking mechanism with a respective engaging member by moving said resilient member of said at least one locking mechanism axially with said threaded fastener, wherein said respective engaging member associated with the second face of said group of faces, and * I I I. I *:* wherein said interlocking automatically accomplished by rotating : *. said threaded fastener in said closing direction by a rotational angle the magnitude of which is not smaller compared to a predefined : *. threshold, and wherein said locking member confined within a *.I.volume enclosed by the projection of said fastener face onto said object face and the envelop of said bore.9. A method as in claim 8, wherein said at least one locking mechanism further comprises a slot disposed circumferential to any member selected from a group of members consisting of said body and said bore, and wherein an elongated and bendable tongue one end of which connected to a first end of said slot implements said resilient member.10. A method as in claim 9, wherein a niche enclosed by the free end of said elongated and bendable tongue and the second end of said slot implements said locking member.11. A method as in claim 9, wherein a protrusion extending off the free end of said elongated and bendable tongue implements said locking member.12. A method as in claim 9, wherein said elongated and bendable tongue is forced to bend by rotating said threaded fastener at least at one rotational angle the magnitude of which does not exceed said : ** predefined threshold, and wherein said elongated and bendable *...tongue spontaneously sprung when said rotational angle exceeds : *.. said at least one predefined threshold. S. * I* * S.13. A method as in claim 9, wherein said at least one predefined threshold is selected in consideration with the length of said elongated and bendable tongue and the pitch of said threads.