Abstract:
An actuator device which includes a stationary support structure, a movable member displaceable relative to the structure, and a wire of a shape-memory material, which extends in the structure between two anchoring elements and the movable member such that the wire shortens when an electric current flows therethrough, causing a displacement of the movable member against the action of a counteracting member. In the structure there are provided two deflection members disposed along the path of the shape-memory wire, each one between the movable member and the corresponding anchoring element of the wire, such as to cause a deflection of the wire between each anchoring element and the movable member.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a National Stage of International Application No. PCT/EP2012/076303 filed Dec. 20, 2012, claiming priority based on Polish Patent Application No. 397476 filed Dec. 20, 2011, the contents of all of which are incorporated herein by reference in their entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to electrically-controlled actuator devices, in particular for use in electric household appliances. 
     2. Background 
     U.S. Pat. No. 6,494,225 B1 discloses an electrically-controlled actuator of the kind for use in a proportional flow control valve, wherein a shape-memory wire extends between two ring connectors fixed to a support structure by means of screws or the like and connected to an electric connector block by conductive leads or wires. 
     U.S. Pat. No. 8,051,656 B1 discloses another electrically-controlled actuator device comprising a wire of a shape-memory material. 
     DE 10 2006 043 919 A1 discloses a dispenser for dispensing different washing agents in a washing machine, comprising a shape-memory-alloy element. 
     Electrically operable actuator devices comprising a wire made of a shape-memory material are also disclosed in U.S. Pat. No. 7,270,135 B2. 
     In said prior document, with particular reference to  FIGS. 3 and 4  thereof, there are disclosed actuator devices wherein the shape-memory wire extends between two anchoring elements and the movable member, such that it follows an essentially V-shaped path. 
     Such actuator devices allow, however, to cause only limited displacements of the associated movable member. The magnitude of such displacements is, in fact, dependent on the length of the available shape-memory wire. 
     An object of the present invention is to provide an improved actuator device of the above-specified kind. 
     SUMMARY OF THE INVENTION 
     This and other objects are achieved according to the present invention by an electrically-controlled actuator device having the features described herein. 
     The invention is also directed to a washing agents dispensing or distributing device, or the like, particularly for a dishwashing machine, comprising an electrically-controlled actuator device as specified above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further characteristics and advantages of the invention will become apparent from the following detailed description, provided merely by way of a non-limiting example, with reference to the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of an electrically-controlled actuator device according to the present invention; 
         FIG. 2  shows the device of  FIG. 1 , without the support structure thereof, and 
         FIG. 3  is a rear perspective view of a washing agents dispensing device, for a dishwashing machine, comprising an electrically-controlled actuator device according to  FIGS. 1 and 2 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to  FIG. 1 , an electrically controlled actuator device  1  according to the present invention comprises a support structure  2  which is stationary in the operation, and which is made, for instance, of an electrically insulating material, such as a moulded plastic material. 
     In the illustrated embodiment, the support structure  2  comprises an envelope  3 , shaped essentially as a box or a tub, possibly provided with a closing cover which is not illustrated in the drawings. 
     In the illustrated embodiment, at one end the envelope  3  has an external tubular formation  4 , wherein a passage is defined through which an axially translatable rod  5  extends. 
     The rod  5  extends mainly inside the envelope  3 , and protrudes outside with its end indicated  5   a  in  FIG. 1 . 
     The other end  5   b  of the rod  5 , which extends inside the envelope  3 , carries an essentially semi-circular deflecting formation  6 , provided with a peripheral groove  7 , which is correspondingly semi-circular. 
     Inside the envelope  3  a helical spring  8  is disposed around the rod  5 , and tends to urge the latter to a condition retracted in the envelope  3 . 
     The internal region of the envelope  3  is divided into a main chamber  9 , in which the rod  5  extends, and an adjacent chamber  10  in which a printed-circuit board  11  is fixed. 
     The plate  11  carries two connection members  12  and  13 , made of an electrically-conducting material, which in the illustrated embodiment are in the shape of male plug blades. 
     The connection members  12  and  13  extend themselves inside a formation  14  provided in one piece with the envelope  3 , on the side opposite the tubular formation  4 . 
     The formation  14  is at least partially open toward the outside, to allow the connection members  12  and  13  to be coupled with an external control circuit (not shown). 
     By SMW in the drawings there is indicated a shape-memory wire which, inside the envelope  3 , has its ends soldered (or otherwise connected) to the plate  11  (see in particular  FIG. 2 ). 
     In the embodiment shown in the drawings, close to the ends of the wire SMW there are fastened respective anchoring elements  15  and  16 , for instance shaped like disks, which are engaged and retained in respective receptacles  17  and  18  predisposed in the envelope  3 , above the chamber  10 . 
     With reference to  FIG. 1 , the upper and lower walls of the receptacles  17  and  18  have respective slots to allow the passage of the portions of the wire SMW which extend from both sides of the corresponding anchoring elements  15  and  16 . 
     The portions  19 ,  20  of the wire SMW comprised between the anchoring elements  15 ,  16  and the plate  11  are relatively loose. 
     Thanks to the above-described solution, in the operation a shortening of the wire SMW, due to the passage of an electric current therethrough, does not stress the soldering points of the ends of said wire to the plate  11 . 
     Starting from the anchoring element  15 , the shape-memory wire SMW extends (upwardly for the observer of  FIGS. 1 and 2 ) in chamber  9  of the envelope  3  up to a first deflection member  21  placed at a higher level with respect to the lower end of the rod  5 . 
     The deflection member  21  conveniently includes a pin which is solid with the envelope  3 , and a bush  22 , for instance made of metal, which is rotatably disposed thereabout. 
     The wire SMW is deflected around the bush  22 , downwardly toward the end formation  6  of the rod  5 . 
     The wire SMW then slidably engages in the semi-circular groove  7  of said formation  6 , and emerges therefrom extending (still upwardly for the observer of  FIGS. 1 and 2 ) toward a second deflection member  23 , likewise provided in the chamber  9  of the envelope  3 , at a level higher than the lower end  5   b  of the rod  5 , on the side opposite the deflection member  21  with respect to the rod  5 . 
     Also, member  23  can conveniently include a pin solid with the envelope  3 , on which a bush  24 , for instance made of metal, is rotatably mounted. 
     The shape-memory wire SMW passes around the bush  24 , and extends thereafter downwardly to the anchoring element  16 , and then up to the printed-circuit board or plate  11 . 
     At the board or plate  11  the ends of the memory-shape wire SMW are connected to the connection members  12  and  13 , possibly through a resistor having a positive temperature coefficient (PTC resistor), intended to limit, in operation, the current flowing through said wire SMW. 
     Due to the presence of the deflection members  21 ,  22  and  23 ,  24  between the lower end  5   b ,  6  of the movable rod  5  and the anchoring elements  15  and  16 , the shape-memory wire SMW undergoes two deflections, forming conspicuous bends at said deflection members. 
     As a whole, between the anchoring elements  15  and  16  the shape-memory wire SMW follows a path which is shaped essentially like an M. 
     By virtue of the plurality of deflections of the path of the wire SMW, the useful length of said wire is quite remarkable, and allows to cause displacements of the rod  5  having a large magnitude, though the overall dimensions of the actuator device  1  remain small. 
     When an electric current passes through the wire SMW, the latter undergoes an axial shortening. 
     Since the anchoring elements  15  and  16  are fixed, the shortening of the wire SMW causes the upper end  5   b  of the rod  5  to protrude upwardly, passing thus from a retracted condition to a (relatively more) extracted condition, in which it remarkably protrudes outside the envelope  3 , through the tubular formation  4  of the latter. 
     When the passage of current in the wire SMW is turned off, said wire cools down and expands, allowing the rod  5  to return to its retracted condition under the action of the counteracting spring  8 . 
     The presence of the bushes  22  and  24  on the deflection pins  21  and  23  allows to avoid that the wire SMW wears said deflection pins. 
     The actuator which has been described above with reference to  FIGS. 1 and 2 , as in general all actuators using shape-memory wires, has a reliable operation, with repeatable features for an extremely high number of activations or operating cycles. 
     In  FIG. 3 , at D is indicated as a whole a washing agents dispensing device, of a per se known kind, particularly for a dishwashing machine. 
     The device D essentially comprises two dispensing sections  30  and  40 , for dispensing a washing agent like a powder detergent, and a liquid rinsing agent, respectfully. 
     Dispensing devices of that kind are disclosed for instance in patent applications DE 19 756 679 and DE 19 545 773. 
     The dispensing device D is of the (per se known) kind wherein the two dispensing sections  30  and  40  can be selectively activated in sequence, through subsequent activations of a same control member  50 , activations which are conveniently caused through an electrically operable actuator device  1  of the kind described above, incorporated in the dispensing device D. 
     In the application illustrated in  FIG. 3 , the actuator device  1  according to the invention conveniently replaces a traditional electric solenoid actuator, being much simpler, less expensive and more reliable than that. 
     Naturally, the principle of the invention remaining the same, the embodiments and the details of construction may be widely varied with respect to what has been described and illustrated by way of non-limiting example, without departing from the scope of the invention as defined in the annexed claims.