An actuator having such quick release function is known from EP 0 685 662 to Linak A/S, and the present invention is a further development of this.

The example given in EP 0 685 662 of operating the quick release function is based on two cylindrical elements, where one with a Y-shaped rocker arm can be urged into the other, whereby the two cylinders due to a guideway are rotated in relation to each other. As a result the coupling spring is released, as its outwardly bent ends engaging tracks in the cylinders are rotated away from each other, causing the coupling spring to expand and thereby release its grip around the cylindrical coupling parts.

The present invention provides a different solution to operating the coupling.

The invention is characterized in that the two cylindri- cal elements are provided with an exterior toothing, and that the release has a corresponding toothing which may be caused to mesh therewith for mutual rotation of the cylinders. Hereby it is possible to construct the quick release just as short as the coupling spring used. In contrast, the quick release according to EP 0 685 662 is longer, as one of the cylindrical elements extends a dis- tance beyond the spring. According to the invention, both cylindrical elements may be contained within the length of the spring, they may even be made shorter. There is the additional advantage that the elements may be

identical. However, it is preferred that the elements abut each other and are formed with mutual guides.

The toothing may either be located on the curved surface of the cylinders or on the end faces thereof, the first mentioned location being preferred as this is obviously the simplest. Irrespective of the location, it will be understood that the extent of the toothing may be limited according to the desired movement. On the other hand, the simplest thing is that the toothing extends all the way around. On the curved surface, however, it may be an ad- vantage to limit the width of the toothing according to the width of the release, such that the rest of the sur- face may be used for other purposes such as guide or braking surface.

The release may be designed as two separate elements which activate their respective cylindrical elements, but this basically complicates the construction.

A Y-shaped release where a first leg and a second leg are formed with a toothing which may be caused to mesh with the toothing on the one or the other cylindrical element, respectively, simplifies the construction and may be used in connection with a toothing on the curved surfaces of the cylindrical elements as well as on the end faces.

With a toothing on the end faces directed toward each other, the release is arranged between the two cylindri- cal elements, otherwise the release rides over the two cylindrical elements in the longitudinal direction. Axial displacement of the release will then cause the two cyl- inders to rotate in opposite directions.

The construction may be configured such that the Y-shaped release, from a retracted position, is laterally dis-

placed into mesh with the cylindrical elements. When the legs have a smooth portion from their dividing point and a distance downwards and with the toothing arranged on the outer part of the legs, the release may be seated down over the cylinders, and pulling thereof may cause the toothing to mesh with the cylindrical elements.

To avoid unintentional release of the quick release the release is spring-loaded to assume a rest position, where the toothing is not in mesh with the cylindrical ele- ments.

This presents at the same time the possibility of operat- ing the release by means of a cable. By pulling the cable the coupling may be completely disengaged, i. e. that the connection is completely interrupted. Alternatively, the coupling may be released in a controlled manner such that a partial release of the coupling is achieved, resulting in a controlled movement of the activating element. The cable may be mounted directly or indirectly on the re- lease. In case the cable in the application of the actua- tor is in direct extension of the release, it is expedi- ent to mount the cable directly on the release. If, on the other hand, the direction of the cable is perpendicu- lar to the release, then the connection may be estab- lished by a mechanism which, when being operated, con- verts a rotary movement or an axial movement into a move- ment perpendicular thereto. An example are mechanisms based on a spindle and nut or a wedge-shaped disc.

A linear actuator according to the invention will be de- scribed in more detail in the following with reference to the accompanying drawing, in which:

Fig. 1 shows a longitudinal section through the ac- tuator, Fig. 2 shows a cross-section through the actuator, and Fig. 3 shows an enlarged view of the release for the quick release.

As shown in the drawing, the main parts of the actuator are constituted by a housing 1 with a reversible electric motor 2 which, through a worm gear 3, drives a spindle 4 having a spindle nut 5 to which an activation rod 6 sur- rounded by an outer tube 7 is attached. The actuator is of the same type as described in the international appli- cation WO 02/29284 Al to Linak A/S, and reference is made thereto.

The actuator has a quick release function comprising two coupling parts 8,9, where one part 8 is fitted perma- nently on the spindle, while the other part 9 is fitted permanently on the worm wheel 10 of the worm gear. More precisely, the side of the worm wheel facing the front end of the actuator is constructed with a cylindrical section, upon which a bushing with a corbie-step is fixed. The coupling part 8 on the spindle is constructed with a bowl which is seated over this corbie-step. A coupling spring 11 is fitted around the two parts 8,9, extending between the side of the worm wheel and a collar on the coupling part 8. In normal conditions, the spring 11 couples the two coupling parts 8,9 together, such that the spindle is connected to the motor via the worm gear.

Around the coupling spring 11 there are two cylindrical elements 12,13 provided with an exterior toothing. The

ends of the coupling spring 11 are bent radially outwards and are embedded in their respective elements.

A Y-formed release 14 rides with its legs over the two cylindrical elements 12,13 such that one leg is opposite to one element, while the other leg 15 is seated down over the other element 13. The upper portion of the legs is smooth, while the lower portion is provided with a toothing to engage the toothing on the elements 12,13.

The neck 16 of the Y-formed release 14 is controlled in a sleeve 17 fixed to the housing. On the neck there is a spring 18 which tightens between a shoulder in the open- ing of the sleeve and the upper side of the release, such that the release is spring-loaded in a parking position, where the lowest, toothed part of the legs is out of con- tact with the two cylindrical elements 12,13. A cable 19 connected to a operating handle (not shown) is fixed to the top end of the neck.

When the handle is pulled, the release is pulled up, as shown in Fig. 2, until the lower toothed part 20 of the legs engages the respective cylindrical elements 12,13, which are then turned opposite each other. The ends of the spring will then be pulled from each other, one clockwise and the other counterclockwise. In this way the spring will expand, i. e. its internal diameter will in- crease and the two coupling parts 8,9 are then released.

The spindle will then be released and can rotate freely.

If the activation rod 6 is under load and if it is in an extended position, it will then be pushed inwards, de- pending on the load being able to overcome the self-lock- ing ability of the spindle.

Although the embodiment relates to a linear actuator, it is obvious, as is also apparent from the claims, that the invention is also applicable in rotary actuators, e. g. of the type described in WO 01/17401 Al to Linak A/S.