Safety screw assembly and operating key thereof

This invention relates to a safety screw assembly and operating key. The head of the screw is movable between a position where it is rotationally integral with the body and a position where it is freely rotatable. The head of the screw has on one face, an opening or a relief, that matches a relief or an imprint formed on part of the operating key. One end of the body of the screw has a stator and a rotor. The head of the screw forms a housing for receiving the rotor, and the assembly forms a translationally movable securing component which is movable between a loose position, where the head is freely rotatable and the rotor and the stator are rotationally integral, and a locked position, where the head and the stator are rotationally integral, where the key has at least one component for setting the rotor into rotation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to international patent application no. PCT/FR2018/050479, filed on Mar. 1, 2018, which is herein incorporated by reference in its entirety.

Not applicable.

THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT

Not applicable.

REFERENCE TO A SEQUENCE LISTING

Not applicable.

Not applicable.

BACKGROUND OF THE INVENTION

This invention relates to a safety screw assembly and operating key thereof.

The term screw here refers to a component mechanically linking at least two elements. This screw, made of metal or another rigid material, is generally elongated and, over at least a part of its length, has a thread and, at one end, a part called the head that enables the screw to be operated. This screw is adapted to operate in conjunction with an internal thread that matches its thread when a screw is inserted by screwing, thus by a combined rotational and translational movement, into the threaded housing that matches its shape.

The operation of this screw is performed by a screwdriver or key tool, one end of which matches the shape of an imprint formed on the screw head.

Although the use of screws makes it possible to establish links between at least two elements, the fact remains that this link is reversible. This is because the tool for screwing the screw into its threaded housing also enables the screw to be removed from the threaded housing by a rotational movement in the opposite direction.

This characteristic is, in many cases, desirable in order to facilitate the maintenance or dismantling of elements. However, in some cases, it is desirable that the ability to screw and/or unscrew is limited to certain users. The reasons for this restriction are generally protection and/or safety requirements, either for the user or for the equipment on which the screw is located, or both.

By way of non-exhaustive examples, mention may be made of locking screws for a vehicle wheel, screws holding a connection cover between two machine-tool elements in a closed or open position, screws closing a cover or an access door to a given area, whether this area is a volume accessible to living beings, humans or animals, or is an interior volume of an object in the broad sense. In these cases, it should generally only be possible to remove and/or insert the screw if this action is performed by an authorized person.

To meet this constraint, safety or antitheft nuts or bolts are known. These are bolts or nuts whose head has an imprint, in positive or negative relief, with a special geometrical shape, requiring a special tool with a matching shaped imprint to operate this nut or bolt. FR-A-2 728 318 presents this type of bolt. Also known from WO-A-2012 040 800 are safety bolts, where any attempt to unscrew causes part of the head to break, this part then becoming freely rotatable and preventing any transmission of rotational movement, whether for screwing or unscrewing, to the entire bolt. Also known from WO-A-2012 148 050 or WO-A-2005 012 737 are cap-type protection devices, positioned on the screw head, which prevent the nut from being loosened and/or stolen.

Although these various solutions are generally satisfactory as a means of limiting the theft of an object or to avoid unauthorized unscrewing, they nevertheless have certain disadvantages. This is because the number of technically possible geometric shapes for the screw head imprint is relatively limited and it is easy to obtain a tool that fits these imprints.

As a result, anyone with a suitable tool can operate the screw or bolt concerned, especially when these screws or bolts are used to secure the mounting of vehicle wheels. This is because it is easy to obtain a specific tool from the usual suppliers in the automotive or car repair sector.

Moreover, for some of the solutions presented by the documents cited, this implies a final implementation and single use of the securing means. In other words, once the safety configuration has been set, the screw is no longer removable, or at least not easily.

Also known from US-A-20021029596 is a safety screw with a dedicated key enabling the screw to be locked or the screw head to be set into free rotation. For this, the key enables a magnetic component to be moved that can only be translationally moved. Here, the key itself is not secured.

Under these conditions, the invention aims to provide a safety screw assembly and operating key thereof, which is easy to use and suitable for the quick insertion and removal of the screw, without this operation being possible by an unauthorized person.

BRIEF SUMMARY OF THE INVENTION

For this purpose, the subject of the invention is a safety screw assembly and operating key thereof comprising said screw formed of a body and a head, the head being movable between a first position where it is rotationally integral with the body and a second position where it is freely rotatable, the head having, on one face, an opening or a relief, the shape of which matches a relief or an imprint formed on part of said operating key, characterized in that an end of the body of the screw comprises a first part called the stator, and a second rotationally movable part, called the rotor, the head of the screw defining a housing element for receiving the rotor, and in that the assembly comprises a translationally movable securing component, said component being movable between a first securing position, called the loose position, in which the head is freely rotatable, and the rotor and the stator are rotationally integral, and a second position, called the locked position, in which at least the head and the stator are rotationally integral, and in that the key has at least one component for setting the rotor into rotation.

In this way, it is possible, by rotating the key, to set the rotor into rotation and, as a result, to secure or rotationally disengage the head and the body of the screw by a translational movement of the securing component. This rotation of the rotor is, advantageously, obtained by a mechanical and magnetic link between the key and the rotor. For this, magnets are inserted into the key and rotor. If a single magnet is used, the latter may, alternatively, consist of several magnetized segments of different polarities or, if several magnets of different polarities are used, it is conceivable that the rotor and the key can only be magnetically linked, and therefore rotationally secure, for a specified key/rotor torque. Thus, tightening or loosening of the screw is secured and only an authorized person with the appropriate key can use the screw. Furthermore. the fact that magnetic means are used prevents any attempt to forcibly establish a link between the head and the rotor by the known means of picking a lock.

Depending on the advantageous but non-obligatory aspects of the invention, this assembly may comprise one or more of the following characteristics:The stator comprises two cylindrical parts with a circular base, the smaller-diameter part having a bottom with at least two wells forming housing elements to receive pistons that are translationally movable in a direction parallel to the longitudinal axis of the body.The rotor comprises two parts whose shape matches the parts of the stator, the smaller-diameter part comprising at least two wells forming housing elements to receive the magnets housed in the rotor.The wall of the larger-diameter part of the rotor has a helical incline terminated by two stops.The securing component is a flat ring fitted with at least one tab extending outwards and coplanar to the solid part of the ring.The securing component is said flat ring fitted with five tabs extending outwards and coplanar to the solid part of the ring.The ring comprises two reliefs extending towards the inner aperture of the ring, coplanar with the solid part of the ring adapted to operate in conjunction with the stops of the slope when the ring is in position on the larger-diameter part of the rotor.The inner face of the head has an annular groove adapted to receive the tab(s) of the ring when the head is in a freely rotatable configuration.The inner face of the head has at least one longitudinal groove, one end of which opens onto the annular groove, and is adapted to receive at least one tab of the ring when the head is rotationally integral with the rotor.The inner face of the head has five longitudinal grooves, one end of which opens onto the annular groove, and is adapted to receive the five tabs of the ring when the head is rotationally integral with the body of the screw.The operating key comprises said component for setting the rotor into rotation, of which there is at least one, fitted with at least one magnet whose polarity matches the magnet, of which there is at least one, housed in the rotor.

DETAILED DESCRIPTION OF THE INVENTION

FIG.1shows a screw1belonging to a screw assembly and key according to one embodiment of the invention. The screw1comprises a cylindrical body with a circular and threaded base2. The length, diameter and thread pitch of the body2are preferably chosen from standardized screw data. Alternatively, this data is specific and adapted to how the screw1is used.

A cylindrical screw head3with a circular base is fitted to one end4of the body2. The end4is a component of the stator of the screw1. The outer face5of head3has a through opening6. Here, the opening6is pentagonal with straight walls. Alternatively, it can be in another form that is not shown: for example, hexagonal or octagonal with curved walls.

A bottom7blocks part of the opening6, as can be seen inFIG.1. The bottom7is independent of the head3. It consists of a rotor25. The bottom7is flat and made of a material permeable to magnetic waves. In this case it is made of metal.

A lug8is fixed perpendicularly to the bottom7, in the vicinity of the periphery thereof. As is apparent fromFIG.8, the lug8is cylindrically shaped and is positioned in the center of a hole80, so that its top is coplanar with the bottom7. In another embodiment, the bottom7has more than one lug and/or of different shapes. For example, one or two lugs8extend perpendicularly from the bottom7.

FIG.2shows an operating key9according to one embodiment. The shape of key9is cylindrical. Advantageously, it is made of a non-corrosive metal, for example stainless steel. Alternatively, it is made of polymers or of a composite metal- and polymer-based material.

One end of the key9is formed by a relief10, whose shape matches that of the opening6of the head3. Here, the relief10is pentagonal. Once inserted into the opening6, the dimensions of the relief10make it possible, by rotating the key9around its longitudinal axis A9, to turn the head3of the screw in one direction or the other, as per the double arrow F9. In other words, the relief10makes it possible for the screw1to be tightened or loosened. The key9makes it possible to tighten it with a given, specific tightening torque for each screw assembly and key, as needed.

The opposite end of the key9with the relief10is formed by the relief11, with a cylindrical circular base and a flat and circular top. The dimensions of the relief11enable the relief11to be inserted into the opening6, but without the rotation of the relief11causing the head3to rotate.

FIG.9shows another embodiment of an operating key90in compliance with the invention. The key90is also cylindrical. The functionally identical elements between the keys9;90have the same references, multiplied by a factor of ten. The end relief100of the key90is therefore identical to the end relief10of the key9. The relief110of the key90is identical to the relief11of the key9.

As is apparent fromFIG.9, the top120of the relief110is flat and circular. It has a hollow relief13whose shape matches that of the lug8and the well80located on the bottom7. The top12of the relief11is similar to the top120of the relief110. It also has a hollow relief, similar to the relief13and not visible in the various figures.

It is conceivable that during insertion of the relief11or110into the opening6, there is complementarity of shape between the lug8, the well80and the relief13so as to angularly position the relief11or110in the opening6and on the bottom7.

At least one cylindrical magnet is therefore housed inside the relief11;110, behind the flat metal top12;120. This magnet may be monopole or multipolar. Depending on the complexity of the desired coding, several magnets, preferably multipolar magnets, will be used. In this case, according to an advantageous embodiment of the invention, there are three multipolar magnets. This term refers to magnets made from several parts, here cylinder segments, which alternate their polarities. One end of such a magnet therefore has a given alternation of south and north poles, with a given angular orientation. This arrangement is known per se from EP-A-1 601 848.

Thus, the keys9;90of two different embodiments of the invention are cylindrically shaped, with identical ends10;100and11;110. They differ by their central parts, also called the main body.

The main body14of the key9is formed of two coaxial sleeves15,16. The sleeve15has a zone150of greater external diameter than that of the other part151constituting the sleeve15. The zone150thus forms a gripping ring of the sleeve15. By means of translational movement in accordance with the double arrow F, the zone150enables the end11to be brought into or out of the sleeve15, more particularly in part151. During periods when the key9is not used, protection of the end relief11and, more specifically, of its top12is therefore provided. This is because the flat top12must be protected against any impact and/or deformation in order to guarantee the integrity of the magnets housed in the end11and to enable the lug8to be secured with the lug13. To allow the passage of magnetic radiation emitted or received by the magnets inserted into the relief11, it is conceivable that the top12will be thin, which, de facto, reduces its mechanical resistance to impacts and deformation. In an embodiment that is not shown, a protective cap, for example screwable or clip-on, is provided to protect the relief11or110.

The sleeve16, the outer diameter of which is similar to the outer diameter of the part150, ensures that the key9is engaged and able to operate during the tightening or loosening of the screw1.

The key90comprises a main body17comprising an outer sleeve170. The sleeve170receives an inner, coaxial sleeve171with the end relief110. The sleeve171is screwed, or alternatively slides, into the sleeve170. This ensures, by means of a helical movement or translation in a direction parallel to the longitudinal axis A90of the key90, that the sleeve171enters and exits the end relief110.

FIG.3shows the body2of the screw only, without the head3.

The non-threaded end4of the body2is cylindrically shaped, with a circular base and open. The end4comprises at least one, advantageously three, housing elements18in the form of circular cylindrical wells. The wells18are suited to receive translationally movable pistons in a direction parallel to the longitudinal axis A2of the body2. For more legibility, the pistons are not shown inFIG.3. The housing elements18, with the pistons and the end4, define a stator.

The access openings of the housing18are coplanar with the bottom19of the end4. The bottom19is flat and circular.

The cylindrical outer wall20of the end4has at least one, advantageously five, rectangular notches21formed at the free upper edge of the wall20. The notches21are evenly distributed on the wall20.

The interior volume of the end4is defined by two coaxial cylinders and of different diameters. The smaller-diameter part22extends from the bottom19to about half the height of the wall20.

The part23is the terminal part of the end4and extends the part22outwards. Thus, the larger-diameter part23defines the access to the volume of the end4, and therefore to the stator as defined above.

An annular groove24is formed on the outer face of the wall20, specifically at the junction zone between the parts22and23.

The end4forms a housing element with an access opening of diameter greater than that of the bottom of the housing. The end4is adapted to receive a part25with a matching shape called rotor.

This rotor25is shown inFIGS.5and6. It comprises a cylindrical part with a circular base26whose outer diameter is smaller than the internal diameter of the part22, so that the part26, once inserted into the part22, is maintained therein while also being freely rotatable. The part26has at least one, advantageously three, wells27.

The wells27are cylindrical with a circular base and each with a longitudinal groove28. The wells27are adapted to receive magnets, which may or may not be multipolar, with a given angular position, not shown and known per se. Each magnet is rotationally fixed in its well27by a relief formed on the magnet and inserted into the groove28.

The rotor25comprises a second part29, also cylindrical with a circular base.

The bottom7of the part29is common with the closed end of the part26and thus defines the bottom of the wells27. The bottom7is visible when the rotor25is in place in the end4and the head3caps the rotor25. Thus, the bottom7of the part29of the rotor25forms a visible flat interface between the outside and the magnets of the rotor, as shown inFIG.1.

The outer face of the wall30of the part29features a helical incline31. The incline31comprises the stops32, at the top and bottom dead centers.

FIG.4shows the head3only, according to two angles of view. The head3is in the form of a cylindrical cap with a circular base, fully open at one end and with an opening6formed on the opposite face5of the head3. The inner face33of the head3has at least one, advantageously five, longitudinal grooves34, here on the rectangular cross-section, running parallel to the longitudinal axis A3of the head3. An annular groove35is formed on the face33of the head3and located at one end of the grooves34, in the vicinity of the bottom of the head3, therefore of the face5. Another annular groove36is formed on the inner face33. This groove36is parallel to the groove35and intended to, partially, receive a connecting ring or clips when this ring or these clips is/are inserted, also partially, into the annular groove24of the wall20of the end4of the body when the head3is in position on the body2. Disassembly of the head3is therefore prevented, while its rotation in relation to the body2is authorized.

FIG.7shows an embodiment of a rotating securing component37of the rotor25with the head3. The component37is configured as a flat ring. At least one, advantageously five, in this place rectangular, tabs38extend outwards from the solid part39of the ring37. The tabs38are coplanar with the solid part39. Two reliefs40, also coplanar with the solid part39, extend therefrom towards the central aperture of the ring37. The tabs38match the shape and dimensions of those of the grooves34.

FIGS.11to17show the various positions of the constituent elements of a screw1and the operation of the screw with a key according to one embodiment of the invention.

FIGS.11and12show the screw1as a cross-section along two longitudinal sectional planes forming between them an angle in the vicinity of 120°, in a configuration where the head3is said to be rotationally loose.

In this configuration, the head3, mounted on the body2, is freely rotating around the aligned longitudinal axes A2and A3, while the body2is rotationally fixed. The rotor25is rotationally integral with the body2, more particularly with the end4. Thus, the inner face33of the head3is not rotationally integral with the wall20of the end4of the body2while also being connected thereto. In other words, the head3is rotationally loose but is integral with the body2and cannot be detached therefrom.

This configuration is obtained by mounting the ring37between the head3and the rotor25. The ring37is mounted around the helical incline31of the rotor25, the latter being positioned in the end4, with the part26of the rotor25having the magnets opposite the wells18, in the part22of the end4.

The rotor25is held in position in the end4. A seal, not shown, is inserted into an annular groove42, visible inFIG.6, and positioned on the outer face of the part29.

When the ring37is on the helical incline31, the tabs38extend outwards from the end4through the notches21. The translational movement generated by the helical incline31of the rotor35is limited by the stops32of the rotor25when in contact with the reliefs40of the ring37. The movement of the ring37is limited by the rotation of the rotor25, rotation limited to about a quarter of a turn by the contact between the reliefs40of the ring37on the stops32of the incline31. The tabs38inserted into the notches21ensure that the ring37and the end4of the body2are rotationally integral. In other words, the ring37provides a link between the head3and the body2.

When the ring37is in an upper position on the incline31, it is positioned at the bottom of the head3, at the level of the groove35. In this case, the tabs38have been displaced translationally in a guided manner in the notches21and the grooves34of the head3. Since the grooves34open onto the groove35, the tabs38are de facto inserted into the groove35at the end of the movement. It can be seen that this translational movement of the ring37results from rotational movement of the rotor25.

When initiating a rotational movement of the head3, irrespective of the direction of rotation and/or the range of movement, the grooves34are shifted in relation to the tabs38of the ring37, which remains rotationally fixed. As the tabs38are no longer engaged with the grooves34, the head3is rotationally disengaged from the end4of the body2of the screw1.

The tabs38in position in the groove35enable the head3to rotate freely in relation to the body2of the screw1. Insofar as the opening6formed in the head3enables the screw1to be tightened or loosened, it is not possible to perform these operations: only the head3, and not the rest of the screw1, is set into rotation. This so-called loose configuration is therefore a secure configuration, no change is possible to the position of the screw1, whether tightened or not.

Maintaining the ring37in position in the groove35is optimized by the springs41occupying the bottom of the head3in one direction of thrust, and by the rotor25itself in the opposite direction of thrust.

This is because in this configuration, the springs, not shown, inserted into the wells18push the pistons towards the rotor25. Under the action of the springs, the ends of the pistons, are partially inserted into the housing elements27of the rotor25receiving the magnets.

In this configuration, the rotor25is rotationally locked by the pistons in relation to the rest of the body2. In this position, while the ring37is in the position in the groove35, only the head3can rotate freely around the aligned axes A2, A3.

This configuration, also called disengaged, also corresponds to a so-called coding configuration of the magnets in the rotor25. This is because the magnets are rotationally and translationally fixed.

To move from this position to a so-called engaged position, in which the head3is rotationally integral with the body2, it is necessary to operate the rotor25with a key9or90.

FIGS.16and17show this operation using a key90, it being understood that the operation is identical using a key9. The end120is inserted through the opening6and positioned so that the lugs13and8are in contact. In this way, the magnets of the rotor25are aligned with those of the relief120. In other words, the positioning is guided, the lugs13and8acting as locating pins.

As is apparent fromFIG.17, a spring43pushes the lug13onto the lug8, thus securing the positioning of the relief120on the bottom7of the rotor25. In this alignment configuration of the magnets of the rotor25and the key90, the polarities of the same sign, north or south, of the magnets of the relief120and the rotor25are opposite each other.

Since the magnets of the rotor25are translationally movable in the housing elements27, with this translation being guided by the grooves28which prevent the magnets from rotating, the magnets of the rotor25move towards the stator, namely towards the wells18of the end4. In this way, the pistons are pushed back to the bottom of the wells18. The pistons are no longer partially inserted into the housing elements27and thus no longer rotationally lock the rotor25.

It is then possible, with a movement of the key90, to set the rotor25into rotation, as per the double arrow F90. This rotational movement is possible due to the link between the lugs13and8. The rotational movement of the rotor25translates the ring37on the helical incline31. Translation is only possible when the tabs38of the ring37are opposite to the grooves34of the head.

As shown inFIGS.14and15, when the tabs38are engaged in the grooves34, the head3is rotationally integral with the ring37. By locking the reliefs40on the stops32in the lower position on the incline31, this ring37is rotationally integral with the stator, therefore with the end4of the body2.

In other words, the ring-shaped securing component37provides a link between the stator, formed by the end4and the pistons, and the head3, with these elements being fixed in relation to each other. The user can then tighten or loosen the screw1with the relief10or100of the key9or90.

The presence of a flat bottom7, without any opening or joining plane prevents any fraudulent forcing of the rotor25. In other words, since magnets with different polarities are present, only a given key enables the rotor25, and therefore the screw1, to be operated, it being understood that this key cannot be copied if the arrangement of the magnet(s) of the rotor25is not known.

This assembly has applications in, for example, securing the closure of an access cover for elements controlling and/or operating machine tools, automatic barriers, access points, parking meters, traffic lights, street lamps, vending machines for products or services, mailboxes, and security boxes, electrical cabinets or otherwise.

In other embodiments, a key enables several screws with the same magnetic coding to be operated.

Alternatively, a key can receive the reliefs11;110, whether removable or not, enabling the operation of several screws or sets of screws with different codings.

In another embodiment, the key has more than one relief receiving magnets: for example, a set of reliefs each fitted with magnets coding for a given screw series.

Alternatively, the screw is operated by a known tool, with the head opening configured to match a standardized geometric shape.

In another embodiment, the head opening is configured to receive only the relief fitted with the magnets. The screw is tightened or loosened by a key engaged with the outside of the head, which, for example, has an external pentagonal shape.

In another embodiment not shown, the relief operating the head of the screw is hollow and its inner volume receives the relief fitted with the magnets. The latter is translationally movable: for example, by sliding in the first relief. Thus, we go from a configuration where, once the relief with the magnets has been released, it is only possible to set the rotor into rotation in a configuration where, once inserted into the operating relief of the head, the screw can be set into rotation. In other words, in this embodiment, one relief serves as a protective sleeve for the other.