5 The invention relates to a connecting device comprising a plug element and a socket element which can be coupled thereto.

⁵⁴ Such connecting devices are known in various embodiments.

In this connection, reference can be made to the plugs and sockets conventional for connecting electric cords. Another 10 example is constituted by the known connectors for hoses.

A drawback of these known coupling devices is that they can take only little tensile force.

If the known devices were of such design that some tensile force could indeed be taken, a simple, easy operation would no 15 longer be possible. As a consequence, the known plug-socket combinations have only a limited field of application.

The object of the invention is to provide a connecting device of the type described above which has a wide field of application and is suitable for taking relatively great tensile 20 forces, so that such a connecting device can also be used in situations wherein traditionally hooks, knots, bolts and nuts, buckles, bow shackles and the like are used.

To this end, according to the invention, a device of the type described is characterized in that the plug element 25 comprises a base member and a rotary head, mounted on the base member for rotation about a rotary shaft which extends in the direction of insertion, which rotary head is held in a first rotational position relative to the base member by spring force and can be rotated against the spring force through a 30 relatively slight angle to a second rotational position in which the plug element can be inserted into the insertion opening of the socket element, the insertion opening of the socket element being widened at at distance from the insertion ,-i end of the insertion opening by means of at least one recess,

35 which recess permits rotation of the rotary head to the first rotational position for assuming a locking position, with at

least one portion of the rotary head being received in the at least one recess; and that means are provided for bringing the rotary head, when in the locking position, into the second rotational position again so as to allow the plug element to be pulled out of the insertion opening of the socket element.

The invention will be further described hereinafter with reference to the accompanying drawings of some exemplary embodiments.

Fig. 1 schematically shows in front view an exemplary embodiment of a plug element according to the invention;

Fig. 2 shows the plug element of Fig. 1 in side view;

Fig. 3 shows the plug element of Fig. 1 and Fig. 2, fitted in a socket element according to the invention;

Fig. 5 shows an example of a modification of an assembly of plug and socket according to the invention;

Fig. 6 shows another modification;

Fig, 7 schematically shows an example of a plug element according to the invention designed as a plug for an electric cord; Figs 8-10 schematically show another exemplary embodiment of a connecting device according to the invention;

Figs 11 and 12 schematically show a plug element according to the invention designed as a cap; and

Figs 13 and 14 show another variant of the invention. Figs 1-3 schematically show a first exemplary embodiment of a plug element 1 and a complete connecting device according to the invention. The plug element comprises a base member 2 and a rotary head 3, mounted on the base member. In the example shown, the base member and the rotary head have substantially the same shape and dimensions in front view. In the rest position, however, the rotary head, as shown, is rotated to somewhat about the common longitudinal centre line y of the rotary head and the base member, so that in the rest position the shaded portions 4,5 of the rotary head extend beyond the contour of the base member. The angle α of this rotation should be sufficiently great to enable portions 4 and 5 to lock to a

sufficient extent behind an edge in a socket element in order to couple the plug element and the socket element firmly. In a practical embodiment, the angle can be 10 degrees, for instance, but the magnitude of the angle α also depends on the shape and dimensions of the plug element and the requirements to be met in a practical situation with regard to the mechanical strength of the connection.

The rotary head can be aligned with the base member against a spring force. For this purpose, the rotary head in the example of Figs 1-3 is journalled in the base member by means of a central shaft 6 which extends into the base member. The shaft 6 is locked in a chamber 8 in the base member by means of a locking pin 7 or a similar element. The chamber 8 is shaped so as to permit a rotation through at least the angle α. Further, a torsion spring 9 is fitted in a hollow of the base member, this spring in the present example being designed as a helical spring. The chamber accommodating the spring may adjoin the hollow 8 directly, but may also be a separate chamber 10, as shown. The chamber 10 shown is located directly behind the rotary head in the base member.

One end of the torsion spring is fixedly connected to the rotary head or to the shaft 6 and the other end of the torsion spring is fixedly connected to the base member. If the rotary head is brought into a position in alignment with the base member and is subsequently released, the torsion spring 9 brings the rotary head to the rest position again, shown in Fig. 1, wherein the portions 4 and 5 extend beyond the contour of the base member.

The rest position may be defined by the spring, but is preferably defined by a stopping means, which may for instance be formed by the pin 7. This offers the possibility of mounting the spring with pre-tension to create a greater resetting force.

Fig. 3 shows the plug element of Figs 1 and 2, fitted in a socket element 12. The socket element has an insertion opening 13, adapted to receive exactly the rotary head 3 and at least

the portion 14 of the base member that is located directly behind the rotary head, if during the insertion movement the base member is at least briefly brought into a position in alignment with the rotary head. Spaced from the front face 15, where the insertion opening 13 ends, the socket element has recesses or one single, combined recess, allowing the rotary head to move from the position in alignment with the base member to the rest position again under the influence of the spring force of the torsion spring. In that case, the portions 4 and 5 fall into the recess (es), preventing the plug element from being pulled out of the socket element again.

In the example shown in Fig. 3, the recesses are windows 16,17 in the wall of the socket element. The connection formed by the plug element coupled to the socket element can be disconnected by pushing, at one of the windows 16 or 17, against the portion of the rotary head that is accessible at that location, so that it is aligned with the base member again. Subsequently, the plug element can be pulled out of the socket element.

Preferably, the rotation angle α of the rotary head and the wall thickness of the socket element are matched such that the portions 4 and 5 of the rotary head do not extend beyond the contour of the socket element. Thus, the connection is prevented from disconnecting unintentionally, which is particularly important if the connection is subject to a certain tensile stress.

The windows 16, 17 can be open, as shown, but can also be closed by a flexible outer wall, capable of being depressed to an extent sufficient to bring the rotary head into the position in alignment with the base member. Such an outer wall can be an integral part of the socket element, in particular if the socket element is made of a suitable synthetic material. Alternatively, it is possible to provide the socket element, at least at the windows, with a flexible and/or resilient jacket

which tightly embraces the socket element, as indicated in Fig. 6 at 18.

It is also possible to form a resilient lip at the windows, cut loose from the material of the socket element on three sides, by means of which the rotary head can be pushed out of the rest position.

Further, it is possible to form in the socket element only an internal recess for the portions 4 and 5 of the rotary head and to provide the base member with means for controlling the rotary head. Fig. 2, by way of example, shows a pin 20, which extends in a slot 19 in the plug element, is connected to the shaft 6 of the rotary head and is operable at the circumference by means of a knob 21 for moving the rotary head out of the rest position and hence out of the locking position. If so desired, the pin 20 can also be designed as a locking member enabling the rotary head to be fixed in one of the two positions, or, optionally, in either position. For this purpose, a separate locking member can also be provided. In that case, the torsion spring could even be omitted. The resetting force for the rotary head can be obtained in various manners. Fig. 4 shows an exemplary embodiment in which the rotary head comprises a flat tongue 30 of resilient material, extending into a complementary slot 31 of the base member. Fig. 4a shows the position in which the rotary head is in alignment with the base member and in which the tongue 30 is twisted and exerts a resetting force. In this example, the tongue 30 has two resilient fingers 32 at the end remote from the rotary head, provided with arrowhead-shaped heads 33, constituting beards that lock behind an edge of a widened portion 34 of the slot 31.

To permit the connection of a plug element and a socket element according to the invention to be effected as easily as possible, the base member may be provided with bevelled portions, constituting run-on faces at the level of the projecting portions 4 and 5 of the rotary head. A plug element provided with such run-on faces 40 is schematically shown in

Fig. 5. In the exemplary embodiment shown in Fig. 5, the rotary head also comprises a bevelled front edge 41, constituting a locating face.

Fig. 6 shows a section at a window of a socket element, in which a plug element is fitted. The socket element comprises a flexible jacket 18 and one of the portions 4 or 5 of the rotary head, projecting in the locking position, extends into the window 16 or 17. In this example, the portions 4,5 of the rotary head are provided with an undercut 42, engaging a bevelled side edge 43 of the window. The rotary head is pushed by the undercut 42 against the side edge 43 of the windows by a resilient tongue in the socket element. This construction yields an extra locking against undesirable loosening of the connection. To disconnect the connection, the plug element should first be pushed somewhat further into the socket element, whereupon the rotary head can be reversed by exterting a pressure, indicated by an arrow 45, on the jacket 18 and the plug element can be pulled out of the socket element.

The plug and socket elements described can very suitably be used for interconnecting ends of ropes, belts, bars, chains, straps, safety belts and other elongated objects, but also for coupling a tool to a handle or grip, for instance a rake element to a rake handle. It is also possible to integrate a plug element or a socket element into any object that is to be detachably fixed to another object. One might think of, for instance, a sliding or revolving door comprising a plug element according to the invention provided with a rotary head with a bevelled locating face and/or a base member with run-on faces. In that case, the socket element is a hollow in the doorcase rebate. For releasing the connection, a push-button may then be provided with which the rotary head can be pushed out of the locking position. Conversely, the plug element may also be fitted in the doorcase rebate and the socket element may be formed or mounted in the door. Depending on the intended use, the plug and socket elements can be made of light or thin-walled material, for

instance synthetic material, or of heavier material, such as metal.

Obviously, the plug and socket elements should be provided with means for fastening the elements to the objects to be interconnected. Fig. 5, at 47, schematically shows, by way of example, a conventional fastening means for belts and straps and the like.

In the exemplary embodiments shown in Figs 1-6, the rotary head and at least the portion of the base member located directly behind the rotary head, as well as the complementary insertion opening in the socket element have, in front view, an elongated shape with rounded ends. As a result, the two projecting portions 4 and 5 are formed upon rotation of the rotary head relative to the base member or the recess in the socket element, which portions effect the coupling between the plug element and the socket element. However, it is also possible to choose a triangular or square or any other form or combination of forms, as long as the rotary head can assume a first position, with the rotary head, viewed in the direction of insertion, falling entirely within the contour of the base member, and a second position, realized by rotating the rotary head relative to the first position, with one or more portions of the rotary head extending beyond the contour of at least the front portion of the base member. If there is sufficient space between the rotary head and the front portion of the base member for an edge in the insertion opening of the socket element, thus enabling portions of the rotary head to grip behind that edge, it is not even necessary for the rotary head and the front portion of the base member to have the same shape. Of course, in that case, the front portion of the insertion opening should have a shape adapted to the front portion of the base member. Further, the front portion of the base member should be received in the recess of the socket element so as to be restrained from rotation, at any rate if the rotary shaft of the rotary head corresponds to the longitudinal centre line of the base member.

It is also possible to use an eccentric rotary shaft. An exemplary embodiment is shown in Figs 8-10 _r which show that in the case of an eccentric rotary shaft it is even possible to use a rotary head that is circular in front view. Fig. 8 shows in front view, in the same manner as Fig. 1, a base member 50, comprising a rotary head 52, rotatable about an eccentric shaft 51. By. means of a torsion spring or the like, the rotary head is held in a position that is to some extent rotated relative to the base member, in which position a portion 53 of the rotary head extends beyond the contour of the base member. However, against the spring force the rotary head can be brought into a position which aligns with the base member. Fig. 10 shows an example of a socket element matching the plug element of Fig. 8 and Fig. 9 shows a section, taken on the line IX-IX of Fig. 10, of the plug element of Fig. 8, inserted into the socket element of Fig. 10. The socket element 54 has a bore 55, capable of receiving the round rotary head 52 and the front portion of the base member 50. At a distance from the entrance face 56 of the bore 55, the bore is widened such that the rotary head, briefly aligned with the base member while the plug element is inserted into the bore 55, can rotate again relative to the base member into the position shown in Fig. 8.

In the example shown, the enlargement of the bore is obtained by providing a number of windows 57, which may or may not be covered by a thin wall or thin jacket, or lips cut loose from the wall of the socket element. The windows render it possible to push the rotary head into a position again in alignment with the base member and the bore so as to allow the connection to be disconnected. Provisions can be made on the base member and the front portion of the socket element, for instance consisting of a projection 58 on one part and a complementary recess 59 on the other part to ensure that the plug element can be inserted into the socket element in one position only. In that case, one single window may also suffice, because the projecting part 53 of the rotary head will then always be in the same position.

If the rotary shaft of the rotary head is formed by a hollow bush, such a bush can serve as a passage for a lead or for material. A bush with a relatively large cross-section can for instance serve as a part of a fluid line, that is if the bush continues through the base member or connects to a corresponding passage in the base member and the socket element. Thus, with the use of the principle of the invention, a hose coupling can be constructed.

Fig. 7 shows an example of an electricity plug 60, comprising a rotary head 61, a base member 62 and a connector part 63, located in front of the rotary head and provided with connecting points or bushes 64. The rotary head is rotatably mounted by means of a bush 65, secured in the base member and in the connector part. Reaching through the bush 65 and a passage connected thereto in the base member and in the connector part is an electric cord 66, whose cores 67 are connected in the connector part in a conventional manner to the pins or bushes 64. The socket element is not shown, but this element has again a widening insertion opening for receiving portions of the rotary head that extend beyond the contour of the base member in the rest or locking position. Obviously, the recess should be sufficiently deep to receive the connector part as well. Further, means should be provided, in the manner described above, that allow the rotary head, when located in the socket element, to be rotated out of the locking position. It is observed that after the foregoing, various modifications will readily occur to a person skilled in the art. Examples of possible modifications have already been described hereinabove. According to another modification, the base member comprises one or more projecting parts, which, upon rotation of the base member relative to the rotary head, can be received in recesses formed at a distance from the front face of the insertion opening in the socket element . Such an embodiment renders it possible, for instance, to integrate the connector part of the plug of Fig. 7 with the rotary head.

Another application of the principle of the invention is schematically shown in Figs 11 and 12. Fig. 11 shows in cross section a modification of a plug element according to the invention, designed as a cap for a container, for instance a bottle or a tank. The cap has a jacket 70. In recesses 71 in the jacket, locking elements 72 are arranged, mounted for rotation about a shaft 74, which locking elements, against a spring force of spring elements not further shown, can be brought to a position falling within the contour of the cap (Fig. 11a), but which normally extend inwardly (Fig. lib) . In this latter position, the locking elements may extend under an outwardly extending collar 73 of, for instance, a bottle neck, as shown in Fig. 12. In the example shown, two locking elements 72 are used. A very safe closure is obtained by using more, for instance three, locking elements.

According to still another modification, the socket element could have a slot-shaped insertion opening, so that the plug element can be slidably coupled to the socket element. An example is schematically shown in Figs 13 and 14, showing such an embodiment in cross section and in top plan view respectively. Figs 13 and 14 show a U-shaped rail 80 having inwardly facing flanges 81. The rail 80 constitutes the socket element. The plug element 82 has a neck 83, fitting precisely between the inwardly facing flanges, which neck 83 prevents the plug element from rotating, and a rotary head 84, in the rest position fitting into the rail behind the flanges 81. The rail may be provided with recesses so as to bring the rotary head into a position in alignment with slot 85 of the rail and to permit removal of the plug element. Alternatively, the plug element itself may be provided with means for bringing the rotary head into the aligned position, for instance in a similar manner as indicated at 19 and 21 in Fig. 2. Also, the plug element may again comprise a locking device, capable of locking the rotary head in a particular position. When an I-shaped rail is used, the principle of the cap with two locking elements, shown in Fig. 11, can be applied,

which elements are then located in flanges fitting round the rail.

If, in addition, means are provided for fixing a plug element relative to the rail, the shown combination of plug element and rail-shaped socket element can be used for constructive purposes, for instance in stand construction.

These and similar modifications are considered to fall within the scope of the invention.