Rotary actuator" D E S C R I P T I O N

The invention relates to a rotary actuator, in particular for moving shutters. Numerous rotary actuators are known in the art, used for example for rotating shutters of gates, doors and also robot members. Reference shall be made here to the first of these. Generally, these actuators are formed by an electric motor and by a mechanical arm (or a bracket) kinematically connected to the output shaft of the motor. The arm is connected during the installation of the actuator to the shutter, which can thus rotate, thrust or drawn into motion by the arm. An example can be seen in the document US 5.102.377.

Some known electromechanical actuators 11 for a shutter 13 - see fig. 1 - have a box casing 10 in which a motor is inserted, and whose shaft 12 - see the bottom view detail in the circle of fig. 1 - projects from the bottom part of the bottom 16 of the casing 10 in order to sustain and drive an arm 14. The bottom 16 of the casing 10 is flat and has a radial toothing 18 with which a movable catcher 20 interacts, catcher used to define the opening end of the arm 14 movement, and thus of the shutter 13 movement. By means of clamping screws 22 and corresponding threaded holes (not shown) in the bottom 16, the catcher 20 can be fixed as desired along the toothing 18, with which the catcher 20 is stably engaged due to its own corresponding toothing (not shown). A protective cover 24 covers part of the bottom 16, the junction between the motor and the arm 14 and also the catcher 20.

During the installation, the angular movement of the arm 14 is decided upon. The maximum opening position of the shutter 13 is defined (opening end-position), according to the requirements of the single application, with the position of the catcher 20 on the toothing 18. When the arm 14 being moved encounters the opposition of the catcher 20, the motor comes under stress and the control unit of the actuator 11 commands its stopping. The other stop is obtained by simply taking advantage of the resistance of the gate frame on the shutter 13 when it is closed.

The making of these actuators involves several disadvantages. The number of components is high and affects the production costs. The position of the catcher 20 causes some difficulties and/or inconveniences when adjusting after the installation (one must disassemble at least the cover 24 and in some cases also the actuator 11). Moreover, in order to ensure multiple positions of the catcher 20 on the toothing 18, one is required to make a number of holes on the casing 10, which increases its production steps and weakens its structure. The same toothing 18 is costly to make, since it complicates the production of the moulds. The object of the invention is to obtain an actuator of the described type which is simpler and cheaper to produce. Another object is to obtain a more reliable actuator. Another object is to obtain an actuator which has an adjustment of the opening stop position which

can be easily set, even after installation.

Such objects are obtained with an electromechanical rotary actuator comprising a motor enclosed in a casing, a rotating arm connected to the motor in order to set in motion a shutter or a leaf, a movable catcher (or equivalent opposing element) to define one end of the circular stroke of the arm (i.e. it defines the position of an end-stop), a cover placed over the rotation centre of the arm, characterised in that the catcher is mounted outside the cover.

The characteristic of the invention allows adjusting the end-stop without disassembling anything, since the catcher is situated outside the actuator and is therefore immediately accessible. The catcher can be applied to the cover for externally interfering with the arm. For example, if one uses a bracket as catcher, it can be fixed to the cover with an orientation such that a part thereof ends up colliding with the arm in the desired stop point.

One advantageous solution, which reduces size and increases reliability, consists of making one or more through-openings in the cover through which the catcher can extend inside the cover, so as to interfere with the movement of the arm there. Here the openings are obtained on the cover and not on the casing, the first being much simpler and cheaper to industrially produce than the second.

A very effective embodiment of the described variant is obtained if a circular series of through-openings is made in the cover, which allows multiple angular positions of the interfering part of the catcher (and thus of the stop point). The catcher can have one or more expansions adapted to penetrate into a through-opening, or it can be composed of a body which is totally insertable in the openings (for example a pin). The making of the expansions results particularly simple and effective by bending one end of the catcher, in order to have the expansions in the form of tabs. Another advantageous variant is had if the catcher comprises an element of elongated form which is rotatably pivoted to one end of the cover. A reduction of the components is obtained if the elongated element is pivoted to the cover by means of the same pin of the arm, allowing it, in this manner, a movement analogous to a watch hand. Thus the free end of the catcher can be moved along a circumference arc and establish a stop point. Hence the movable end can, in one case, reach and insert itself into the through-openings made on the cover, defining a stop inside the cover, and in the other (if the stop point is outside the cover) it can come into contact with the arm in a point outside the actuator, due for example to a suitable curving of the elongated element.

In the case of internal end-stop, a stop element can be effectively mounted on the arm, element adapted to collide with the extension of the catcher inside the cover so as to ensure a reliable detection of the end-stop. One particular conformation of the actuator is obtained if the cover comprises a plate which has a circular seat in which an analogous circular head of

the arm is rotatably supported (to give stability to the arm movement). A stop element can be integrally arranged on the head, element which extends inside a circular groove obtained inside the seat, in the surface of which (groove) one or more through-openings are obtained. In this manner, the expansions of the catcher pass through the wall of the cover inside the through-openings and are positioned inside the groove in the stop point set by the user. When the arm enters into rotation, the stop element likewise moves inside the groove, and has a circular stroke limited at one end, i.e. by the point of collision with the catcher's expansions.

One convenient variant consists of connecting the motor to the arm by means of the engagement of a pinion on an internal gear present on a circular head of the arm itself, which involves greater compactness and save of pieces.

The advantages of a device in accordance with the invention will be more evident from the following description of a preferred embodiment, which makes reference to the attached drawing set: Fig. 1 shows a known actuator;

Fig. 2 shows a three-dimensional top exploded view of an actuator according to the invention;

Fig. 3 shows a three-dimensional bottom exploded view of the actuator of fig. 2; Fig. 4 shows a bottom view of part of the actuator of fig. 2; Fig. 5 shows a catcher of the actuator of fig. 2.

In fig. 2 and 3, an electromechanical rotary actuator 52 is shown in its entirety according to the invention. It comprises an electric motor (not shown), enclosed in a casing 50, which drives a rotating arm 56 by means of a pinion 83, arm in turn connected to a gate shutter (not visible) so as to move it, and a lower cover 58 which can conveniently have support and guide functions of the arm. The cover 58 comprises a plate 60 where a circular seat 62 has been obtained, at whose interior a circular groove 68 is present, seat which rotatably supports a circular head 64, with corresponding size, of the arm 56. It is noted how the plate 60 also has a protective function of the rotation point of the arm 56. A stop element is integrally arranged on the head 64; in this example such element is in the form of a projecting tooth 66. The tooth 66, once the head 64 is inside the seat 62, extends inside the circular groove 68. In this manner, by the rotation of the arm 56 (see arrow F in fig. 2), the tooth 66 moves inside the groove 68. One or more through-openings 70 (of which only some are shown) are present on the surface of the groove 68, openings arranged in a circular series (or annulus).

Below and outside the plate 60, a catcher 72 is rotatably connected (fig. 5), angularly movable (see arrow G in fig. 2 and 4), as will be described, in order to define an end-stop of the arm 56. The catcher 72 comprises an elongated element 74 with an eyelet end 76 rotatably connected to the plate 60 by means of a fixing screw 82 (or also for example with bolt, rivet

or equivalent means engaging the eyelet), such that the other end 78 can rotate along a circumference arc. At the centre of the eyelet 76, a hole 87 is provided for the screw 82, which can be screwed inside the end of a pin 90, around which the arm 56 is also pivoted. The free end 78 is provided with two tabs 80 which are orthogonal to the elongated element 74, obtained by bending two portions of the free end 78.

The catcher 72 has a pivoting point on the plate 60 which is concentric to the circular series of openings 70, and is sized such that the free end 78 overlaps the openings 70. Therefore the tabs 80 can penetrate (with a simple manoeuvre) into the respective through- openings 70, and, through these, can extend inside the plate 60 in the groove 68 so as to interfere with the movement of the arm 56.

The electric motor of the actuator 52 is connected to the arm 56 by means of the engagement of a pinion 83, fit on its shaft, with an inner toothing 84 with facing teeth (internal gear with inner toothing) present in an annular cavity 86 in the circular head 64. The functioning of the components described for the actuator 52 is now described. As stated, the arm 56 rests and can rotate in direction F on the plate 60, driven by the pinion 83 of the motor. With this rotation, the tooth 66 moves by a same angle inside the groove 68. During the installation, the catcher 72 is angularly adjusted as desired (movement G in fig. 4) so as to make the tabs 80 penetrate into two through-openings 70 of the plate 60, such that they pass through the plate and occupy a sector of the groove 68. Then the catcher 72 is permanently fixed to the plate 60, by means of the screw 82, in a manner such that it cannot move. Since the tooth 66, rotating with the arm 56, when it encounters one of the tabs 80 inside the groove 68 collides with it and does not move beyond it (the tabs 80 are firmly blocked in the openings 70), it is clear that the angular position of the catcher 72 defines an angular end-stop for the arm 56 (the motor under stress is stopped by the actuator 52 control). Hence one end of the angular stroke of the tooth 66, and consequently the arm 56, is adjustable by varying the angular position of the catcher 72. The other end coincides with the closed position of the shutter, in which the catcher for the arm 56 is the frame of the gate.

Other variants of the invention, like (i) the variation of the form of the movable catcher,

(ii) the arrangement of the through-openings, (iii) the rotatable connection means between the catcher and the cover, (iv) the position of the cover, which can be over the motor, (v) the possibility of using more than one catcher for setting more than one end-stop in an adjustable manner (in a structure with more than one elongated element 74 outside the cover 58, for example, each end —stop mounted on the cover 58 rotatably independent from the other, and advantageously with the same pivoting point and means), are all comprised in the protective scope of the subsequent claims.