"LIMIT SWITCH DEVICE FOR A MOVEMENT OPERATOR, MOVEMENT OPERATOR AND METHOD FOR SETTING A LIMIT-SWITCH POINT"

The present invention relates to an innovative limit switch device to be inserted into the electric circuit of a movement operator for moving movable elements, such as windable roll-up shutters and the like. The invention also relates to a movement operator and to a method for setting a limit-switch point in a movement operator. In the prior art of movement operators for moving movable elements, such as windable roll-up shutters and the like, limit-switch devices are known provided with two cursors coupled with a threaded bar commanded to rotate by the rotation of the operator, so that they slide simultaneously on the bar in a manner corresponding to the movement of the driven element. With each cursor a detecting sensor is associated (in general a microswitch) , which reports when the respective cursor has reached the position corresponding to the limit-switch position desired for the driven element. In order to adjust and vary the two limit-switch positions, it is necessary to adjust the initial position of the two cursors on the threaded bar manually. This generally occurs by releasing two clutches that normally prevent free rotation of the cursors on the threaded bar and manually rotating each cursor to place the cursor in the activation position of the sensor when the element moved by the actuator is in the corresponding desired limit-switch position. In such limit-switch devices the correct setting of the

limit-switch positions is reached via various attempts and the time employed and the setting difficulty are considerable. The time that such an adjusting method requires is particularly clear in the case of operators of the type mounted directly above the winding roller of a roller shutter or the like, where the limit-switch device is accessible only when the roll-up shutter is completely shut (i.e. completely unwound by the roller). This makes it impossible to adjust directly the limit-switch position corresponding to the completely open roll-up shutter and makes it necessary to adjust by trial and error starting with the completely closed roll-up shutter position. The general object of the present invention is to overcome the aforesaid drawbacks by providing a limit switch device, a movement operator provided with such a device and a method for setting a limit-switch point in a movement operator, that enable the limit-switch point to be set automatically, with just a movement of the element driven by the movement operator. In view of this object it has been decided to provide, according to the invention, a limit switch device to be inserted into the electric circuit of an operator for moving movable elements, such as windable roll-up shutters and the like, comprising a rotating control shaft, two detecting sensors each corresponding to one of two end movement positions to be detected by the alternating rotation of the control shaft, two cursors each associated with one of the two detecting sensors and coupled with a threaded bar commanded to rotate by said control shaft to

produce alternating translation of the cursors to the respective sensor as far as a detection point of the cursor by the sensor, characterized in that it comprises in combination, for running an automatic procedure for setting the point of the limit switch for one of the sensors, deactivating means for deactivating detection of the corresponding cursor for the sensor and arresting means for arresting the movement of the corresponding cursor towards the sensor in the point of normal detection thereof by the sensor.

Still according to the principles of the invention, it has been decided to provide an operator unit for moving movable elements such as windable roll-up shutters and the like, comprising a movement reduction gear that is operationally associated with a limit-switch unit according to what is disclosed above to define two end stop positions of the element moved by the reduction gear with an automatic setting of the limit-switch point of at least one of such two end positions. According to the principles of the invention it is been decided to make a method for setting a limit-switch point in a movement operator for moving a movable element, such as a windable roll-up shutter and the like, and provided with a limit switch device that is inserted into the electric circuit of the operator, which is kinematically sensitive to the movement of the movable element and which comprises two detecting sensors, each associated with one of two end movement positions, and two cursors each associated with one of the two detecting sensors and

coupled with a threaded bar that is commanded to rotate by the operator to produce alternating movement of the cursors to the respective sensor as far as a detection point of the cursor by the sensor, the method comprising the steps of: deactivating the action of the sensor corresponding to the limit-switch point that it is desired should be set; moving the movable element to the position corresponding to that of the limit-switch point that it is desired should be set, so as to move or maintain the corresponding cursor towards the point of normal detection thereof by the sensor, simultaneously preventing, by means of a yielding of the connection that causes dragging of the cursor caused by the rotation of the threaded bar, the cursor being able to proceed beyond that point; reactivating the action of the sensor after the movable element has reached the position corresponding to the limit-switch point that it is desired should be set.

In order to explain more clearly the innovative principles of the present invention and the advantages thereof over the prior art with the help of the following attached drawings a possible embodiment thereof applying such principles will be disclosed below. In the drawings:

- figure 1 is a partially sectioned schematic view of a movement operator with a limit switch device according to the invention;

- figure 2 is a partially sectioned limit-switch device along line II-II in figure 1;

- figure 3 is a partial perspective view of a guide element in the limit-switch device;

- figure 4 is a partial view of a zone of the limit-switch device in a normal operating condition.

With reference to the figures, in figure 1 there is shown in longitudinal section a movement operator indicated generally by 10 of the type used for moving movable elements such as windable roll-up shutters and the like. This operator 10 comprising a movement reduction gear 11 and a limit switch device 12 operationally associated in a known manner causes the corresponding driving of the limit-switch device, which is provided with two detecting sensors 13, 14, each corresponding to one of two end movement positions to be detected. The sensors of the limit switch device are inserted in a known manner into the electric circuit of the reduction gear so as to enable the normal operation thereof between the two end stop positions established by the limit switch device. In the device shown in the figures, the sensors are made with limit microswitches .

In particular, the operator 10 shown is of the type intended for being mounted directly on a rolling roller or shaft 15 of a roller shutter or similar windable elements. For this purpose, the operator comprises a wheel 16 with a toothed internal crown for. engaging a cog 17 of the reduction gear and a gear 18 splined on the control shaft 19 of the limit switch device. The rolling shaft 15 traverses axially the wheel 16 and is connected thereto to be rotated by the reduction gear. Advantageously, the wheel 16 is openable radially by means of a known system (not shown) to enable the operator to be mounted on the rolling shaft. A bar or threaded screw 20 is commanded to rotate by the

control shaft 19 to produce a translation of two threaded cursors 21, 22 alternatively in one direction or the other on the bar towards or away from the respective sensor 13 or 14 as far as a detection point of the cursor by the sensor. In the specific case, each cursor activates the microswitch by pushing the perimeter thereof against a driving lever of the microswitch. The two cursors have the same thread to translate in a concordant manner on the threaded bar. According to the adopted conventions, the right-hand microswitch 14 supervises the determination of the closed position (completely unwound roll-up shutter) whilst the left-hand microswitch 13 supervises the determination of the open position (wound roll-up shutter) . As the application varies (height of the roll-up shutter, winding diameter of the drum, etc.), the position of the limit switches has to be set and, in particular, a different distance between the cursors to increase or reduce the stroke between the two limit-switch positions. In prior-art devices, setting this distance and the position of the cursors on the threaded bar is the cause of a long and difficult manual settings, as indicated above.

In the device according to the invention, for running an automatic procedure for setting the point of the limit switch for one of the sensors (the one on the left in figure 1) and then for the distance of the two cursors there is provided deactivating means 23 for deactivating the detection of the corresponding cursor 21 by the sensor 13 and stopping means 24 for stopping the movement of the cursor 24 in the point (shown in figure 1) that is normally detected by the sensor.

Advantageously, the stopping means 24 for stopping the movement of the cursor comprises in combination an abutting element or bush 25 against which the cursor rests when it reaches said point of normal detection and releasing means 26 that enables the cursor to rotate 21 together with the threaded bar 20 when the cursor is pushed against the abutting element.

In particular, the device comprises advantageously a guide 27 that is parallel to the threaded bar and cooperates with the cursor to normally to prevent the rotation thereof. As can be seen well in figure 2, the guide usually engages a notch 28 of a plurality of notches on the perimeter of the cursors so as to enable the cursors to slide axially but not to rotate. Advantageously, the releasing means comprises a corresponding zone 26 of the guide that is made to offer reduced resistance to the rotation of the cursor in said point of normal detection of the sensor. This resistance has a value that is such as to lock the rotation of the cursor when it moves freely but to permit the cursor to rotate together with the threaded bar when the cursor is pushed against the abutting element by the rotation of the bar. Advantageously, as can be seen well in figure 3 where an end part of the guide 27 is shown in perspective, the reduced-resistance zone 26 is made of a plurality of tabs that are elastically yieldable in the rotation direction of the cursor. In this way, the cursor 21, when it reaches the point of normal detection of the limit switch sensor 13 thereof and is locked against further movement by the abutting element 25, starts to rotate with the screw

flexing the yieldable tabs 26. On the other hand, opposite rotation of the screw 20 moves the cursor away from the abutting element, as the torque transmitted by the cursor is reduced to the point that it no longer flexes the tabs 26 and normal movement of the cursor along the guide is obtained.

The cursors are also advantageously movable manually by driving a lever 36 that pivots the guide 27 far from interference with the cursors so as to enable the cursors to rotate manually on the threaded bar.

Advantageously, the aforesaid deactivating means for deactivating detection of the cursor by the sensor (necessary for preventing the movement of the operator being interrupted during the calibrating step, as will be explained below) comprises a support 28 that supports the sensor 13 and that is movable for commanding the sensor to move between a normal detection operating position (shown in figure 4) and the non-operating position (shown in figure 1). Advantageously, the movement from the non-operating position to the operating position is produced by a kinematic mechanism that is sensitive to the movement of the cursor 21 far from said point of normal detection. This kinematic mechanism comprises a driving lever 29 that is moved by the passage of the cursor 21 during the first movement thereof away from the point of normal detection of figure 1. The movement of the lever 29 (to the right in figure 1) disengages a bolt 30 retaining the support 28 in the non-operating position against the action of thrust springs 31 of the support towards the operating position.

In figure 4 there is visible the movement effect of the lever 29 that is rotatably pivoted in 32 on the frame of the device and which comprises advantageously a cam race 33 for moving the bolt (by means of a pivot 24 thereof) so as to disengage the bolt from a seat 35 in the support 28. After the movement of the lever towards the right, it no longer interferes with the movement of the cursor and the limit switch device remains in the normal operating condition. Manual rearming of the lever is possible if it is desired to proceed to a new calibration of the limit-switch point.

From a comparison of figures 1 and 4, it can be noted that, advantageously, the abutting element 25 moves from the operating position thereof (in which the cursor 21 rests against the abutting element 25 when in the position of normal detection of the limit switch) to movement of the support 28 of the sensor from the non-operating position to the operating position. This avoids any further interference of the abutting elements during normal operation of the operator . In order to obtain this movement, it has been found to be advantageous to devise a kinematic mechanism with which the abutting element 25 is pushed by a spring 37 to the non-operating position in figure 4 and is maintained in the operating position in figure 1, against the action of this spring, by a locking tooth 38 that protrudes (monobloc or through interconnection) from the support 28 so as to interfere with the spring movement of the abutting element when the support of the sensor is in the lowered non-operating position. In this way, when the lever 29

releases the bolt and the support moves upwards, the tooth 38 exits the space between the abutting element 25 and the internal wall of the device and the abutting element can slide to the left as far as the non-operating position in figure 4.

Owing to the limit switch device according to the invention, the method for setting a limit-switch point becomes very easy. Substantially, the action is deactivated of the sensor corresponding to the limit-switch point that it is desired should be set automatically and the movable element actuated by the operator is then moved to the position corresponding to that of the limit-switch point that it is desired should be set. This causes the corresponding cursor to be moved or maintained at the point of normal detection thereof by the sensor thereof owing to the fact that the cursor is prevented (by yielding of the connection that causes the cursor to be dragged due to the rotation of the threaded bar) from being able to proceed beyond that point. Lastly, after the movable element has reached the position corresponding to the limit-switch point that it is desired should be set, the action of the sensor is reactivated. For better understanding, an example will now be disclosed of the automatic setting operations of a limit-switch point by means of the device according to the invention. For the sake of clarity, it will be supposed that the operator moves a windable roll-up shutter. The expressions "closed roll-up shutter" and "open roll-up shutter" normally define the two corresponding desired limit-switch end positions for the roll-up shutter.

At the end of the limit-switch point setting step the device is initially in the condition of figure 1 and the roll-up shutter is in the closed position that is completely unwound from the roller 15. In other words, at the start of the setting step the movable element is taken to the limit-switch position opposite that to be set automatically. In order to enable the installer to be able to choose whether to move the roll-up shutter manually or to use the automation thereof, it is necessary for the opening microswitch 30 not to be initially activated (otherwise both microswitches would be activated simultaneously) and is thus in the lower position owing to the movable support 28.

On the other hand, with the roll-up shutter closed, before the automatic learning cycle starts the closing microswitch 14 has to be actuated by moving if necessary manually the respective cursor 22 to the activation position of the sensor, still shown in figure 1.

The fact that the initial condition of the automatic learning cycle coincides with the closed roll-up shutter position (completely unwound) is advantageous as in this position the cursors to be adjusted are accessible.

During the first movement of the roll-up shutter (towards opening) the closing cursor 14 moves to the left to the opening cursor 21, not being able to move left owing to the presence of the abutting element 25 that is an obstacle thereto and owing to the yieldability of the antirotation connection, rotates integrally with the threaded bar and does not move but remains in the limit-switch point. After making the roll-up shutter reach the desired opening

position the fitter reverses the direction of automation motion (electrically or manually by acting on the roll-up shutter) and then also the threaded bar.

During this second movement of the roll-up shutter (towards the closing) both move towards the right: the cursor 21 runs a stroke that is proportion to the height (total stroke) of the roll-up shutter, whilst the cursor 22 will return to the original position until the corresponding closing microswitch 14 is reactivated. This causes the roll-up shutter to stop automatically if the fitter uses automation during the self-learning cycle.

Automatic setting is thus completed. The opening cursor 21 at the start of the movement towards the right advantageously triggers the device that locates the opening microswitch in the definitive operating position where it is activatable by the cursor 21 thereof during regular operation. The abutting bush 25 moves simultaneously to the non-operating position. At this point it is clear how the preset objects have been reached inasmuch as the fitter no longer needs to intervene on the limit-switch device, except in order possibly to finely adjust the automatically determined positions. The setting of the limit-switch point is rapid and precise and may occur by means of a single opening and closing cycle of the roll-up shutter or the like.

Naturally, the above description of an embodiment applying the innovative principles of the present invention is provided by way of example of such innovative principles and must not therefore be considered to limit the scope of

what is claimed herein. For example, the advancing block of the cursor can also be advanced by known means by disengaging thereof from the threaded bar rather than from the antirotation guide. The sensors can also be different from simple microswitches . For example, they may be optical sensors, as is easily imaginable by those skilled in the art. Sensor detecting can also be deactivated electrically, by interrupting the signal emitted by the sensor or the effect thereof on the operator rather than by moving the sensor. Transmission of motion to the threaded bar can occur via kinematic connections that are other than those shown, as can be easily imagined by those skilled in the art.