The invention relates to restrictors, and in particular to restrictors for limiting the maximum opening of a closure such as a window or door. The invention further relates to opening restriction systems having closures.

Restrictors are known for the purpose of limiting the maximum opening of windows or doors to a predetermined opening distance, such as less than 100mm, for example to prevent young children from falling out of the open window.

On the other hand, it is recommended that restrictors should be capable of being readily fully opened, if necessary, particularly in an emergency. GB 2551015 A discloses a cable restrictor for a window, which has a key-operated locking mechanism in order to be able to open the window more or fully by unlocking the locking mechanism with a key.

Restrictors with key-operated locking mechanisms have certain drawbacks for users. If the key is not stored near to the window or in a place easily accessible, it takes time to get the keys. In addition, if the key is different for each window, the right key needs to be selected from amongst other keys. Then, the key needs to be properly inserted in the keyway of the locking mechanism. These operations may be conducted without any difficulties under normal circumstances, but in the case of an emergency such as a fire or blackout, they may become difficult. Another disadvantage with such restrictors is that if the key is lost, the window can no longer be fully opened.

The object of the present invention is to provide a restrictor having a keyless locking mechanism to allow the closure to be readily opened fully when unlocked, whilst at the same time having some degree of child-resistance against unwanted opening of the locking mechanism. Solutions of the problems are described in the independent claims. The dependent claims relate to the further improvements of the invention.

According to a first aspect of the present invention, there is provided a keyless restrictor for limiting the maximum opening of a closure, comprising: a first fixture with a first connector part; a second fixture; and a cable element which is attached to the second fixture at one end and is provided with a second connector part at the other end, wherein the first connector part and the second connector part are configured to be detachably connectable with each other to form a nested connection defining a rotation axis, wherein the first connector part and the second connector part of the nested connection are locked together unless at least two movements of the second connector part in different directions relative to the first connector part of the first fixture are performed.

The present invention therefore provides a restrictor having a simple keyless locking mechanism. In addition, for unlocking, at least two different movements are required, resulting in some degree of child safety.

In a preferred embodiment, the keyless restrictor comprises one or more pairs of a projection and a slot, for locking the nested connection and guiding at least two movements of the second connector part. One of the paired projection and slot may be formed on one of the first and second connector parts, and the other of the paired projection and slot may formed on the other of the first and second connector parts.

In a preferred embodiment, the at least two different movements include a rotational movement of the second connector part relative to the first connector part around the rotation axis. The slot may include a circumferential path which is arranged within a plane orthogonal to the rotation axis and extends in a circumferential direction, or a helical path which extends helically around the rotation axis, in order to guide the rotational movement.

In a preferred embodiment, the slot includes at least one locking path which extends from the circumferential path or the helical path and holds with the projection stopping the movement thereof in the circumferential direction.

In a preferred embodiment, the at least one locking path defines a stop surface to stop the projection so that the second connector part is prevented from detaching from the first connector part.

In a preferred embodiment, the at least one locking path extends in parallel with the rotation axis.

In a preferred embodiment, the circumferential path extends partially in the circumferential direction, and the locking path is formed at each end of the circumferential path.

Alternatively, the circumferential path may extend around the entire periphery.

In a preferred embodiment, the slot includes at least one entrance allowing for the corresponding projection to enter,

In a preferred embodiment, the at least one locking path is arranged apart from the entrance by an angle of 10° or more around the rotation axis. Preferably, the angle is between 30° and 150°, more preferably between 50° and 130°, yet more preferably between 70° and 110°, and most preferably 90°. In a preferred embodiment, the keyless restrictor includes two or more pairs of the projection and the slot, wherein the two or more slots are equidistant from each other around the rotation axis.

In a preferred embodiment, the keyless restrictor comprises at least one elastic body and/or at least one pair of magnets which is arranged between the first and second connector parts and configured to urge the second connector part in such a way that the projection is retained within the locking path of the slot.

In a preferred embodiment, the at least one elastic body and/or the at least one pair of magnets generates a repulsive force between the first and second connector parts.

In a preferred embodiment, the at least one pair of magnets generates an attractive force between the first and second connector parts.

In a preferred embodiment, the at least one elastic body includes a spring, preferably a coil spring.

In a preferred embodiment, the first connector part includes a hole which retains the coil spring therein.

In a preferred embodiment, the hole includes a spiral groove onto which the coil spring screws.

In a preferred embodiment, the first connector part is formed as an anchor post having a circular cross section, and second connector part is formed as a receptacle having a circular or non-circular recess for receiving the anchor post. This allows a stable connection between the first and second connection part. In a preferred embodiment, the receptacle includes at least one guide rib for centering the receptacle on the rotation axis in association with the periphery of the anchor post.

In a preferred embodiment, the receptacle includes a rod extending in the direction of the rotation axis, and the anchor post includes a hole for receiving the rod.

In a preferred embodiment, the cable element is attached to the second connector part in a rotatable manner via a pivot.

In a preferred embodiment, the cable element includes a cable or chain or rope. The cable may be flexible.

According to a second aspect of the present invention, there is provided an opening restriction system, comprising a closure having a movable panel and a frame, the frame movably supporting the panel; and a keyless restrictor according to the first aspect. The first fixture is fitted to one of the movable panel and the frame, and the second fixture is fitted to the other of the movable panel and the frame.

The present invention will now be described by way of example with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a keyless restrictor, in use, in accordance with the present invention, fitted to a window;

FIG. 2 is a sectional view of an exemplary attaching structure for a cable element to a second fixture of FIG. 1;

FIG. 3 is a sectional view of first and second connector parts to form a nested connection, in accordance with the present invention; FIG. 4 is a perspective view of the first and second connector parts having a locking mechanism, with a part of the second connector part cut out;

Fig. 5 is the perspective view of FIG. 4, with another part of the second connector part cut out;

FIG. 6 is a bottom view of the second connector part in accordance with the preferred embodiment;

FIG. 7 is a perspective view of the first fixture of first variant;

FIG. 8 is a plan view of the first fixture of FIG. 7;

FIG. 9 is a side view of the first fixture of FIG. 7;

FIG. 10 is a perspective view of the first fixture of second variant;

FIG. 11 is another perspective view of the first fixture of FIG. 10;

FIG. 12 is a perspective view of the first fixture of third variant;

FIG. 13 is another perspective view of the first fixture of FIG. 12;

FIG. 14 is a perspective view of the first fixture of fourth variant;

FIG. 15 is another perspective view of the first fixture of FIG. 14;

FIG. 16 is a schematic of the movements of the second connector part of the first variant, in order to detach the second connector part from the first connector part;

FIG. 17 is a schematic of the movements of the second connector part of the second variant, in order to detach the second connector part from the first connector part;

FIG. 18 is a schematic of the movements of the second connector part of the third variant, in order to detach the second connector part from the first connector part;

FIG. 19 is a schematic of the movements of the second connector part of the fourth variant, in order to detach the second connector part from the first connector part;

FIG. 20 shows further possible variant of the slot;

FIG. 21 shows further possible variant of the slot; and

FIG. 22 shows further possible variant of the slot. FIG. 1 shows a keyless restrictor 10 in accordance with the present invention, which is in use. The keyless restrictor 10 serves for limiting the maximum opening of a closure.

In the illustrated use, the keyless restrictor 10 is applied to a window W. The keyless restrictor 10 may be fitted to another closure, such as a door. The window W has a movable panel W-l and a frame W-2 which supports the movable panel W- 1 whilst allowing relative movement. The keyless restrictor 10 of the present invention may be used upon a pivoting window as shown, but it should be understood that the keyless restrictor 10 can alternatively be used upon a sliding window or a tilt-turn window, or with a door.

The keyless restrictor 10 includes a first fixture 20 with a first connector part 30 (to be described later) and a second fixture 40.

In use, the first fixture 20 is fitted to one of a movable surface and a fixed surface, and the second fixture 40 is fitted to the other of the movable surface and the fixed surface of the window or door. To this end, each fixture 20, 40 may include a foot plate 22, 42 to be fitted on either the movable surface or the fixed surface, with fixing devices such as screws or nails (not shown). It should be understood that the movable surface means a surface of an opening member of a closure, such as the movable panel W-l, and the fixed surface means a surface of a fixed member of said closure, such as the frame W-2, or a wall surface near the closure. In FIG. 1, it can be seen that the first fixture 20 is fitted on the movable panel W-l, and the second fixture 40 is fitted on the frame W-2. These installation locations may be reversed if desired.

The keyless restrictor 10 further includes a cable element 50 which is attached to the second fixture 40 at one end and is provided with a second connector part 60 at the other end. The cable element 50 provides a flexible connection between the first fixture 20 and the second fixture 40 via the first and second connector parts 30, 60. The maximum opening of a closure depends in principle on the length of the cable element 50, as well as on the installation locations of the first and second fixtures 20, 40, i.e., the relative position of the first and second fixtures 20, 40. The length of the cable element 50 may be predetermined at the time of manufacturing, or may be adjustable on site afterward. The length, strength, and/or material of the cable element 50 may be chosen to comply with legal requirements set in a country or region where the product is used.

A suitable example of the cable element 50 is a cable, more preferably a flexible cable. The cable may be a multi-stranded wire/cable sheathed in a plastic covering. Another example of the cable element 50 may be a chain or rope.

FIG. 2 shows an exemplary attaching structure for the first end of the cable element 50 to the second fixture 40. The second fixture 40 may include a retention portion 44 projecting from the foot plate 42. The cable element 50 may be rotatably attached to the retention portion 44. To this end, the retention portion 44 may include a retention hole 46 with a shoulder 46a which can engage with an enlarged diameter of the first end of the cable element 50. A metal fitting 52 may be crimped or securely attached to the first end of the cable element 50 for the engagement with the shoulder 46a. This rotational flexibility of the cable element 50 relative to the second fixture 40 can be advantageous particularly during the attaching and detaching operation of the second connector part 60 to or from the first connector part 30. In an alternative design, the cable element 50 may be securely fixed to the second fixture 40.

Likewise, as shown in FIG.3, the other or second end of the cable element 50 may be rotatably attached to a retention hole 62 formed in the second connector part 60. The retention hole 62 may include a shoulder 62a which can engage with an enlarged diameter of the second end of the cable element 50. A metal fitting 54 may be crimped or securely attached to the second end of the cable element 50 for the engagement with the shoulder 62a. In an alternative design, the cable element 50 may be securely fixed to the second connector part 60. With further reference to FIGS. 4 and 5, it can be seen that the first connector part 30 of the first fixture 20, and the second connector part 60 are configured to be detachably connectable with each other to form a nested connection with a common rotation axis X. That is, the first and second connector parts 30, 60 can be connected in such a manner that at least a part of one positions inside the other.

FIG. 6 shows a rotation guide means for guiding the rotation of the second connector part 60 relative to the first connector part 30. The details of the rotation guide means will be described later.

Although the first connector part 30 and the second connector part 60 are separate and separable members, the mutually connected and locked state thereof is maintained by a locking mechanism discussed hereinafter; in this manner, the window W or the like can be opened only as far as the position in which the cable element 50 becomes taut, that is, by a predetermined opening distance, such as less than 100mm, at the same time achieving some resistance to mischief by children.

The locking mechanism is configured to prevent the second connector part 60 from releasing from the first connector part 30 by engaging the second connector part 60 with the first connector part 30. The locking mechanism is also configured to be unlocked by at least two movements of the second connector part 60 in different directions relative to the first connector part 30.

Preferably, the locking mechanism is configured to be unlocked by a pushing or pulling movement of the second connector part 60 in a direction of the rotation axis X and by a rotational movement of the second connector part 60, by a user, relative to the first connector part 30 around the rotation axis X. Such distinctly different directions provide more reliable child resistance. Three or more movements, or more complex movements such as zig-zag or wave-like movements are also possible for more reliable child resistance. In the following, the locking mechanism for locking the nested connection will be explained in detailed manner with reference to FIGS. 7 to 15. FIGS. 7 to 9 show a first variant of the locking mechanism; FIGS. 10 and 11 show a second variant; FIGS. 12 and 13 show a third variant; and FIGS. 14 and 15 show a fourth variant.

In each variant, the locking mechanism may include one or more pairs of a projection 70 and a slot 80A-80D ("80" in general), for locking the nested connection and guiding the at least two movements of the second connector part 60. One of the paired projection 70 and slot 80 may be formed on one of the first and second connector parts 30, 60, and the other of the paired projection 70 and slot 80 may be formed on the other of the first and second connector parts 30, 60

In each variant shown, two projections 70 are provided on the second connector part 60, and the corresponding slots 80 are formed on the first connector part 30. Alternatively, only one, or more than two, projection(s) 70 may be provided on the second connector part 60. The reverse or mixed-up arrangement is also possible. That is, the first connector part 30 may have both one or more projections 70 and one or more slots 80, and the second connector part 60 may have both one or more corresponding slots 80 and one or more corresponding projections 70.

In each variant shown, the projection 70 is in the form of a pin, preferably a metal pin. The pin may be formed integrally with the first or second connector part 30, 60, or may be a separate member from the first or second connector part 30, 60 and press-fitted or screwed into the first or second connector part 30, 60.

In a case where more than one projection 70 is provided, these may be arranged at equal intervals in the circumferential direction of the first or second connector part. In each variant shown, two projections 70 are arranged at positions opposing each other.

In each variant, the slot 80 is configured to receive the projection 70. The slot 80 may be in the form of groove, cutout, or hole. The slot 80 may be made by cutting or boring, or may be made at the same time of the production of the first or second connector part 30, 60. For example, the slot 80 may be molded together with the first or second connector part 30, 60, or may be formed simultaneously with the production of the first or second connector part 30, 60 by using 3D printing technology.

In each variant shown, the first connector part 30 is formed as an anchor post projecting from the foot plate 22 of the first fixture 20 and has a circular or generally circular cross section crossing the rotation axis X; and the second connector part 60 is formed as a receptacle defining a circular or non-circular recess for receiving the anchor post. The first connector part 30 may extend in a direction perpendicular to the upper surface of the foot plate 22. The first connector part 30 may have a cylindrical shape. The second connector part 60 may be configured to accommodate the first connector part 30 completely. Preferably, when the recess of the second connector part 60 has a circular cross section crossing the rotation axis X, the inner diameter of the recess is slightly larger than the outer diameter of the first connector part 30 so that the second connector part 60 can smoothly fit on, and rotate around, the first connector part 30.

The reverse arrangement is also possible. That is, the first connector part 30 may be formed as a socket having a circular or non-circular recess; and the second connector part 60 may be formed as a plug which has a circular or generally circular cross section crossing the rotation axis X and is plugged into the socket to form the nested connection. In any case, the second connector part 60 is preferably rotatable relative to the first connector part 30 around the rotation axis X.

With reference to FIG. 6, the second connector part 60 in the form of the receptacle defining a non-circular recess is shown. This second connector part 60 may include the rotation guide means for guiding the second connector part 60 relative to the first connector part 30. The rotation guide means may include at least one guide rib 64 projecting inwardly into the receptacle in a direction toward the rotation axis X, with the result that the second connector part 60 can be positioned concentric with the first connector part 30 as indicated by a dotted line. The guide rib 64 may extend in the direction of the rotation axis X. In the example of FIG. 6, four guide ribs 64 extending in the direction of the rotation axis X are arranged at equal intervals along the circular direction.

In an alternative arrangement (not shown), the first connector part 30 in the form of the socket may include at least one guide rib 64 projecting inwardly into the socket in a direction toward the rotation axis X, with the result that the second connector part 60, as the plug, can be positioned concentric with the first connector part 30.

With reference to FIGS. 4 and 5, a further preferred embodiment can been seen; the first connector part 30 in the form of the anchor post includes a hole 32 at the centre, which extends in the extending or longitudinal direction of the anchor post. The hole 32 opens to the end surface of the anchor post opposite to the foot plate 22. The hole 32 may be a through hole penetrating the foot plate 22, but may be a blind recess. The second connector part 60 in form of the receptacle may include a rod 66 to be inserted in the hole 32. The rod 66 may be arranged in the centre of the recess and extend in the direction of the rotation axis X. The hole 32 and rod 66 may cooperate with each other to guide the axial movement of the second connector part 60, by a user, relative to the first connector part 30.

In each variant, the slot 80 is configured to engage with the projection 70 to form the locking mechanism. In the first variant shown in FIGS. 7 to 9, two slots 80A in the form of the groove are arranged on the outer periphery of the first connector part 30 in the form of the anchor post. These slots 80A are preferably equidistant from each other around the rotation axis X. Alternatively, only one, or more than two, slot(s) 80A may be arranged on the outer periphery of the first connector part 30.

Each slot 80A includes a circumferential path 81A arranged within a plane orthogonal to the rotation axis X and extending in a circumferential direction of the circular anchor post. The circumferential path 81A can guide the rotational movement of the second connector part 60 by a user through engagement with the projection 70. The circumferential path 81A may extend partially in the circumferential direction.

Further, each slot 80A may include a locking path 82A which extends from a first end of the circumferential path 81A and can engage with the projection 70 in the circumferential direction. This engagement can be seen in FIGS. 4 and 5 and prevents the second connector part 60 from rotating relative to the first connector part 30 around the rotation axis X.

First bend 83A, preferably with an acute or right angle, may be provided between the first end of the circumferential path 81A and the locking path 82A.

Preferably, the locking path 82A defines a stop surface 84A which can stop the projection 70 in the detaching direction in the rotation axis X and prevents the second connector part 60 from detaching from the first connector part 30. Such a stop surface 84A can provide another level of security. Preferably, the stop surface 84A faces the foot plate 22 side. More preferably, the stop surface 84A is shaped to substantially match the profile of the projection 70, resulting in more stable locking for the projection 70 located in the locking path 82A. The stop surface 84A may be a concave curved surface matching the profile of the projection 70 with a round pin shape.

Preferably, the locking path 82A extends in parallel with the rotation axis X. By these means, the circumferential movement of the projection 70 located in the locking path 82A is more reliably prevented. An inclined locking path 82A is, however, possible. Such an inclined locking path 82A may be used in a zig-zag or wavy slot.

In the first variant, each slot 80A further includes an introduction path 85A leading to the other or second end of the circumferential path 81A. The introduction path 85A defines an entrance 86A for the projection 70 to enter. The entrance 86A opens to the upper surface of the anchor post. Second bend 87A, preferably with an acute or right angle, may be provided between the second end of the circumferential path 81A and the introduction path 85A.

The introduction path 85A may be parallel to the rotation axis X or may be inclined with respect to this parallel direction. The introduction path 85A may be inclined in such a way that the introduction path 85A starts at the entrance 86A and goes away from the locking path 82A as it approaches the foot place 22. Such an inclined introduction path 85A, in cooperation with the circumferential path 81A and the locking path 82A, requires more complex movements of the second connector part 60 in order to detach the second connector part 60 from the first connector part 30. For example, at least three movements of the second connector part 60 in different directions will be necessary: a pushing movement of the second connector part 60 toward the foot plate 22 to disengage the projection 70 from the locking path 82A; a rotational movement in an anticlockwise direction along the circumferential path 81A; and additional rotational movement in a clockwise direction along the inclined introduction path 85A.

In a preferred embodiment, as shown in FIGS. 7 and 8, the locking path 81A is arranged apart from the entrance by an angle Q of 10° or more around the rotation axis X and/or the circumferential path 81A extends by an angle Q of 10° or more around the rotation axis X. This provides a sufficient length of the circumferential path 81A, which results in more reliable child resistance for the keyless restrictor 10. The angle Q is preferably 30°-150°, more preferably 50°-130°, furthermore preferably 70°-110°, and most preferably 90°.

In a preferred embodiment, a biasing means in the form of at least one elastic body and/or at least one pair of magnets is arranged between the first and second connector parts 30, 60. The biasing means may urge the second connector part 60 in a direction of the rotation axis X, wherein the projection 70 is retained within the locking path 82A of the slot 80A and is preferably in contact with the stop surface 84A of the locking path 82A. This ensures more reliable engagement of the second connector part 60 with the first connector part 30. The elastic body may include a spring, preferably a coil spring 90, as shown in FIG. 3. More preferably, the coil spring 90 is accommodated and retained in the hole 32 of the first connector part 30. The coil spring 90 may push the rod 66 in the direction of the rotation axis X so that the second connector part 60 separates from the first connector part 30. The coil spring 90 may be assembled in the hole 32 by press fitting or screw fitting. In FIG. 3, the hole 32 includes a spiral groove 32a onto which the coil spring 90 screws.

The at least one pair of magnets may be between the first and second connector parts 30, 60. The magnets may be arranged so as to repel or attract each other. One of the paired magnets may be arranged on the first connector part 30, for example on the upper surface of the anchor post; and the other of the paired magnets may be arranged on the second connector part 60, for example on the lower surface of the receptacle facing the upper surface of the anchor post.

Such magnets generate either a repulsive force or attractive force between the first connector part 30 and the second connector part 60. Whether the repulsive force or attractive force is used, depends upon in which direction the locking path 82A extends with respect to the circumferential path 81A. More specifically, as shown in FIGS. 7 and 9, if the locking path 82A extends upward from the first end of the circumferential path 81A, toward the upper surface of the first connector part 30, the repulsive force should be used. Such a repulsive force keeps each projection 70 in contact with the stop surface 84A, thereby, improved engagement of the second connector part 60 with the first connector part 30 is maintained. In this case, the disengaging direction of the projection 70 in which each projection 70 moves away from the stop surface 84A and toward the bend 83A is the pushing direction in the rotation axis X. In contrast thereto, if the locking path 82A extends downward from the first end of the circumferential path 81A, toward the foot plate 22, the attractive force should be used (not shown). In this case, the disengaging direction of the projection 70 in which each projection 70 moves toward the circumferential path 81A is the pulling direction. The principle of engaging and disengaging of the first and second connector parts 30, 60 in the first variant will now be described. For engaging, a user pushes the second connector part 60, to which the end of the cable element 50 is coupled, down onto and over the first connector part 30 in the form of the anchor post, against the repulsive force from the biasing means such as the coil spring 90, with the pair of opposing, inwardly projecting projections 70 engaging in the corresponding pair of profiled slots 80A. Once each projection 70 comes to the bottom (i.e., the second bend 87A) of the introduction path 85A of each slot 80A, the second connector part 60 is twisted through a predetermined angle (90 degrees clockwise in this variant, but either direction and any adequate angular range can be applied). During the angular travel caused by the user twisting the second connector part 60, the opposing projections 70 of the second connector part 60 now travel in the circumferential paths 81A, which may essentially be at right angles with regard to the introduction path 85A. This engagement, being perpendicular to the direction of the bias from the biasing means such as the coil spring 90, prevents the second connector part 60 from being pushed backwards. However, once the angular rotation is stopped by the projections 70 hitting an abrupt change of direction at the bends 83A of the slots 80A, the projections 70 can now move backwards in the direction of the repulsive force until they hit the stop surfaces 84A of the slots 80A (see FIGS. 4 and 5). The second connector part 60 and its attached cable element 50 cannot, therefore, be removed from the first connector part 30 unless and until someone pushes down, particularly hard enough to overcome the repulsive force from the biasing means, and turns the second connector part 60 in the opposite rotational direction until the projections 70 find the entrances 86A of the slots 80A within which they were initially aligned. In the first variant, at least two movements of the second connector part 60 in different directions relative to the first connector part 30 are required in order to detach the second connector part 60 from the first connector part 30.

Accordingly, a restrictor having the simple keyless locking mechanism is provided. In addition, for unlocking, at least two movements of the second connector part 60 in different directions, particularly along the locking path 82A and the circumferential path 81A, relative to the first connector part 30, are required, resulting in some degree of child safety. With reference to FIGS. 10 and 11, the second variant of the locking mechanism is shown.

In this variant, the locking mechanism includes one or more (two, in the example shown) slots 80B, but includes only one circumferential path 81B extending around the entire periphery of the first connector part 30. The circumferential path 81B is arranged within a plane orthogonal to the rotation axis X and extends in the circumferential direction.

Like the first variant, the locking mechanism may include one or more (two, in the example shown) introduction paths 85B defining entrances 86B, and one or more (two, in the example shown) locking paths 82B defining stop surfaces 84B.

The description and preferred embodiments described in the first variant are applicable to the second variant. Some of them can be seen in FIGS. 10 and 11 with the same reference numeral as in the first variant.

This variant allows locking in either clockwise/anticlockwise direction and unlocking in either clockwise/anticlockwise direction and thus facilitates the locking operation of the second connector part 60, but still provides child resistance since at least two movements of the second connector part 60 in different directions are required in order to detach the second connector part 60 from the first connector part 30. To be more precise, the pushing movement of the second connector part 60 to disengage the projections 70 from the locking paths 82B, and the rotational movement of the second connector part 60 along the circumferential path 81B until the projections 70 find the entrances 86B of the slots 80B within which they were initially aligned are required.

With reference to FIGS. 12 and 13, the third variant of the locking mechanism is shown. In this variant, the locking mechanism includes one or more (two, in the example shown) slots 80C, and each slot 80C includes a circumferential path 81C which extends partially in the circumferential direction of the first connector part 30, similar to the first variant. Each slot 80C include two locking paths 82C extending from both ends of the circumferential path 81C via bends 83C. Each slot 80C further includes an introduction path 85C with an entrance 86C between the ends of the circumferential path 81C.

The description and preferred embodiments described in the first variant are applicable to the third variant. Some of them can be seen in FIGS. 12 and 13 with the same reference numeral as in the first variant.

This variant allows locking in either clockwise/anticlockwise direction, but unlocking can only be effected by pushing down the second connector part 60 to disengage the projections 70 from the locking paths 82C, and subsequently twisting the second connector part 60 only in the reverse direction along the circumferential paths 81C. This facilitates the locking operation of the second connector part 60, whilst at the same time ensuring a certain level of the child protection.

With reference to FIGS. 14 and 15, the fourth variant of the locking mechanism is shown.

In this variant, the locking mechanism includes one or more (two, in the example shown) slots 80D. Each slot 80D include a helical path which extends from near the upper surface of the first connector part 30 toward the foot plate 22, with a spiral form around the rotation axis X. The slot 80D may include a locking path 82D extending from first end of the helical path 81D via first bend 83D and defining a stop surface 84D. The slot 80D may further include an introduction path 85D extending from the other or second end of the helical path 81D via second bend 87D. The first bend 83D may have an acute angle. The second bend 87D may have an obtuse angle; or vice-versa. The helical path 81D can facilitate the engagement operation of the second connector part 60 because, during the engagement operation, the rotation of the second connector part 60 by a user can lead the second connector part 60 closer to the first connector part 30.

Another advantage of the helical path 81D is that the helical path 81D can be freely designed with any length, regardless of the number of slots 80D and projections 70. For example, the helical path 81D may be formed over 360 ° or more around the rotation axis X. Surprisingly, this can significantly improve the child resistance. In this case, it is advantageous if the cable element 50 does not hinder the rotation of the second connector part 60 by a user. To this end, it is conceivable to connect the receptacle (i.e., the lower portion of the second connector part 60 accommodating the first connector part 30) and the cable retention (i.e., the upper portion of the second connector part 60 connected to the cable element 50) via a pivot (not shown). This makes it possible to rotate only the receptacle around the rotation axis X without substantially moving the cable element 50.

Of course, the helical path 81D may extend by 360° or less, such as 90°, as illustrated in FIGS. 14 and 15.

The description and preferred embodiments described in the first variant are applicable to the fourth variant. Some of them can be seen in FIGS. 14 and 15 with the same reference numeral as in the first variant.

Although the exemplary slot 80D includes the introduction path 85D communicating between the entrance 86D and the helical path 81D, the introduction path 85D may be omitted. In such a case, the entrance 86D of the slot 80D may be defined by the end of the helical path 81D opposing the locking path 82D.

FIGS. 16-19 summarise how the second connector part 60 (or the projection 70) is moved in different directions relative to the first connector part 30 (or the slot 80) in order to detach the second connector part 60 from the first connector part 30, according to the invention.

FIG. 16 indicates that at least the axial movement al along the locking path 82A and the subsequent rotational movement a2 along the circumferential path 81A are necessary to disengage the second connector part 60, according to the first variant.

FIG. 17 indicates that at least the axial movement al along the locking path 82B and the subsequent rotational movement a2 or a3 along the circumferential path 81B are necessary to disengage the second connector part 60, according to the second variant.

FIG. 18 indicates that at least the axial movement al along the locking path 82C and the subsequent rotational movement a2 only in the reverse direction along the circumferential path 81C are necessary to disengage the second connector part 60, according to the third variant.

FIG. 19 indicates that at least the axial movement al along the locking path 82D and the subsequent rotational movement a4 along the helical path 81D are necessary to disengage the second connector part 60, according to the fourth variant.

Further possible variants can be seen in FIGS. 20 to 22.

FIG. 20 shows a slot 80E having more paths than the first variant. The slot 80E includes an additional path 88E extending from the upper end of the locking path 82E and extending in the circumferential direction. This variant requires at least three movements a5, al and a2 of the second connector part 60 in different directions relative to the first connector part 30 are required, resulting in more improved child resistance. FIG. 21 shows a slot 80F having a zig-zag shape. In this variant, it can be seen that two discrete helical paths 81F and two locking paths 82F are combined in turns. At least two axial movements a6, a8 and two rotational movements a7, a9 to disengage the projection 70 from the slot 80F are required, resulting in more improved child security. Three or more discrete helical paths 81F and locking paths 82F may be provided to form the zig-zag slot.

FIG. 22 shows a slot 80G having a wavy shape. This also requires at least two axial movements a6, a8 and two rotational movements a7, a9 to disengage the projection 70 from the slot 80G, resulting in more improved resistance.

It goes without saying and without showing that a more complicated slot path is possible. Most importantly, however, the present invention is based on the idea that it is difficult for children to move the second connector part 60 in predetermined different directions, particularly rotating the second connector part 60 whilst pushing or pulling the same.