阅读说明：本技术 改进的具有形状记忆线材的致动器 (Improved actuator with shape memory wire ) 是由 法布里齐奥·普罗穆蒂科 埃利奥·塞拉里 于 2018-05-08 设计创作，主要内容包括：本发明涉及一种电致动器(A,A’),其包括转子构件(6)和致动组件(4),所述致动组件构造成干涉所述转子构件(6),从而造成其旋转,其特征在于,所述转子构件(6)包括被布置成干涉所述致动组件(4)干涉的一对偏心浮凸部(63),并且所述致动组件(4)包括形状记忆线材(2),其中,所述致动组件(4)构造成在电流流过所述形状记忆线材(2)的至少一部分时造成所述转子构件(6)的旋转。(The invention relates to an electric actuator (A, A') comprising a rotor member (6) and an actuating assembly (4) configured to interfere with the rotor member (6) causing rotation thereof, characterized in that the rotor member (6) comprises a pair of eccentric reliefs (63) arranged to interfere with the actuating assembly (4), and in that the actuating assembly (4) comprises a shape memory wire (2), wherein the actuating assembly (4) is configured to cause rotation of the rotor member (6) when an electric current flows through at least a portion of the shape memory wire (2).)

1. An electric actuator (a, a') comprising:

rotor member (6) and

an actuation assembly (4) configured to interfere with the rotor member (6), causing the rotor member to rotate,

it is characterized in that the preparation method is characterized in that,

the rotor member (6) comprises a pair of eccentric reliefs (63) arranged to interfere with the actuation assembly (4) and

the actuating assembly (4) comprises a shape memory wire (2),

wherein the actuation assembly (4) is configured such that a current flow through at least a portion of the shape memory wire (2) causes rotation of the rotor member (6).

2. Electric actuator (a, a') according to the preceding claim, characterized in that the actuation assembly (4) is configured to rotate the rotor member (6) alternately in opposite directions.

3. An electric actuator (a, a') according to any of the preceding claims, characterized in that the rotor member (6) is engageable to a member to be moved, such as a driven shaft or the like, so that when the rotor member (6) rotates, a rotational movement is transmitted to the member to be moved.

4. Electric actuator (A, A') according to any of the preceding claims,

the electric actuator includes a Switch (SW), and

the actuation assembly (4) is configured to interfere with the Switch (SW).

5. Electric actuator (A, A') according to the preceding claim, characterized in that it comprises a first electrode (11), a second electrode (12), a third electrode (13) and a movable electrode (14), wherein the second electrode (12) and the movable electrode (14) form the Switch (SW),

wherein one end of the shape memory wire (2) is coupled to the first electrode (11) and the other end is coupled to the third electrode (13), and

wherein the shape memory wire (2) is arranged to assume an electrical coupling with the second electrode (12).

6. Electric actuator (a, a') according to any of the preceding claims, characterized in that the actuation assembly (4) comprises a first and a second actuation member (411, 424, 412, 425) able to interfere in a single direction with the respective eccentric element (63) of the rotor member (6).

7. Electric actuator (a') according to the preceding claim,

the actuating assembly (42) comprises a first pulley (421) and a second pulley (422) around which the shape memory wire (2) is passed, and

the first and second actuation members comprising a first arm (424) and a second arm (425), each arm being rotatable and comprising a respective base portion (4241, 4251) and end portion (4242, 4252), the base portions being shaped so as to interfere with a respective eccentric element (63) of the rotor member (6),

wherein each of said first arm (424) and said second arm (425) has a rest position and an operating position in which the respective end portion (4242, 4252) interferes with said movable electrode (14) to open said Switch (SW) and the respective base portion (4241, 4251) interferes with the respective eccentric element (63) causing the rotor member (6) to partially rotate, and

wherein, when a shape memory wire portion (2) arranged around the first and second pulleys (421, 422) is powered so that an electric current flows through it overheating, said portion of shape memory wire (2) is retracted and the first or second pulley (421, 422) rotates so as to cause a rotation of the respective first or second arm (424, 425), bringing it from the rest position to the operating position and interfering with one eccentric element (63) causing a rotation of the rotor member (6), the other eccentric element (63) of the rotor member (6) being thus arranged in a position such as to allow the rotation of the rotor member (6) only when the other arm (424, 425) rotates.

8. Electric actuator (a') according to the preceding claim,

each of the first and second arms (424, 425) comprises a respective electrical terminal (4243, 4253), and

the electric actuator comprises two return springs (5'), each electrically coupled with a respective electric clamp (4243, 4253), arranged to bring the respective first arm (424) and second arm (425) from the operating position to the rest position.

9. Electric actuator (a') according to the preceding claim,

the shape memory wire (2) has an end coupled to the electrical terminal (4243, 4253), and

one of the return springs (5') is interposed between the third electrode (13) and an electrical clamp (4243) of the first arm (424), and the other return spring (5') is interposed between the first electrode (11) and an electrical clamp (4253) of the second arm (425).

10. Electric actuator (A') according to any of the preceding claims,

the movable electrode (14) includes a protrusion (144), and

the rotor member (6) comprises a pair of cavities (622) arranged such that one of the cavities (622) removably engages with the protrusion (144) of the movable electrode (14) when the rotor member (6) is rotated so as to hold the rotor member (6) in position.

11. Electric actuator (a') according to the preceding claim,

the movable electrode (14) includes a lower laminate (141) and a support (143) coupled with the lower laminate (141) having the protrusion (144), and

the rotor member (6) includes a protrusion (62) on which the cavity (622) is formed.

12. Electric actuator (A) according to claim 6, characterized in that said first and second actuating members comprise a first slider (411) and a second slider (412), respectively, each of which can engage with a respective eccentric lobe (63), wherein said first and second sliders (411, 412) can occupy a rest position and an operating position in which they interfere with said movable electrode (14) to open said Switch (SW),

wherein, when the portion (2) of shape memory wire arranged around one of said first (411) or second (412) slides is supplied with electricity through which an electric current flows overheating, said portion of shape memory wire (2) retracts and said first (411) or second (412) slide moves from said rest position to said operating position and interferes with the respective eccentric element (63) causing the rotation of said rotor member (6), the other eccentric element (63) of said rotor member (6) being therefore arranged in a position such as to allow the rotation of said rotor member (6) only when the other slide (411 or 412) moves.

13. Actuator (a) according to the preceding claim, characterized in that each of said first slider (411) and second slider (412) comprises a respective return spring (5) arranged to keep said sliders (411, 412) in said rest position.

14. Electric actuator (A) according to any of claims 12 or 13,

the movable electrode (14) includes a convex portion (142), and

the rotor member (6) comprises a pair of recesses (621) arranged such that when the rotor member (6) is rotated, one of the recesses (621) removably engages the embossment (142) of the movable electrode (14) to hold the rotor member (6) in position.

15. Electric actuator (A) according to the preceding claim,

the movable electrode (14) comprises a lower plate (141) on which the relief (142) is obtained, and

the rotor member (6) comprises a projection (62) on which the notch (621) is obtained.

16. The actuator (A) according to any of claims 12 to 15,

each of the sliders (411, 412) has a guide (413) along a respective side edge, and

the shape memory wire (2) passes over the two guides (413) of the first slider (411) and the second slider (412) so that it alternately moves the sliders (411, 412) from the rest position to the operating position when the shape memory wire is heated.

Technical Field

The present invention relates to an improved actuator with shape memory wire.

More particularly, the present invention relates to a universal shape memory actuator that is specifically designed and manufactured for reduced assembly steps and has a specifically reduced size.

In the following, the description will be generally directed to an implementation of an actuator for household appliances and machines, but it is obvious that the description should not be considered as being limited to this particular use.

Background

As is well known, actuators using shape memory wires are common on the market today.

Shape memory wires have the known property of "retaining memory" to their shape, which they recover when heated.

Thus, when the shape memory wires are crossed by an electric current and heated by joule effect or when directly heated by a heat source, they return to the original shape.

It is known that: in the manufacture of actuators, it is often difficult to have a connection between the shape memory wire and the electrical terminal described above. This manufacturing step is generally carried out by means of crimping, which consists of the connection of the electrode to the shape memory wire, physically and thus electrically, by means of a suitable tool. This operation is essentially performed mechanically by "pressing" the wire on the electrode, using an additional element to stop the two elements, in order to achieve a good electrical contact.

However, this solution results in high costs in terms of manufacturing.

Moreover, such a process does not always guarantee an optimal coupling over time, also due to the above-mentioned mechanical characteristics of the wire.

In addition to the above difficulties, actuators with shape memory wires are often particularly complex from a structural point of view. This means that despite their constructional and operational advantages they present different problems for their industrialization.

It is clear that the above mentioned limitations of shape memory wire actuators according to the prior art are economically and industrially annoying.

Disclosure of Invention

In view of the above, the object of the present invention is: a shape memory wire actuator is proposed that overcomes the technical problems of the prior art.

Another object of the invention is: an actuator is proposed in which the terminals are fixed to each other by an advantageous coupling method.

The invention also aims to: an actuator of the type mentioned is proposed which has high reliability and technical performance, which can be easily reproduced from an industrial point of view.

Another object of the invention is: a shape memory actuator is proposed having a very compact size to make it easy to install even in small household appliances.

It is therefore a particular object of the present invention an electric actuator comprising a rotor member and an actuation assembly configured to interfere with the rotor member causing its rotation, characterized in that the rotor member comprises a pair of eccentric reliefs arranged to interfere with the actuation assembly and the actuation assembly comprises a shape memory wire, wherein the actuation assembly is configured such that when an electric current flows through at least a portion of the shape memory wire, a rotation of the rotor member is caused.

Always according to the invention, the actuation assembly may be configured so that the rotor members rotate alternately in opposite directions.

Still according to the invention, the rotor member is engageable with a member to be moved, such as a driven shaft or the like, such that when the rotor member rotates, a rotational motion is transmitted to the member to be moved.

Advantageously according to the invention, the actuator may comprise a switch and the actuation assembly may be configured to interfere with the switch.

Advantageously according to the invention, the actuator may comprise a first electrode, a second electrode, a third electrode and a movable electrode, wherein the second electrode and the movable electrode form the switch, wherein one end of the shape memory wire may be coupled with the first electrode and the other end with the third electrode, and the shape memory wire may be arranged to assume electrical coupling with the second electrode.

According further to the invention, the actuating assembly may comprise a first actuating member and a second actuating member able to interfere in a single direction with respective eccentric elements of the rotor member.

Always according to the invention, said actuation assembly may comprise a first and a second pulley, said shape memory wire passing around said first and second pulley, and said first and second actuation members may comprise a first and a second arm, each rotatable and comprising a respective base portion shaped to interfere with a respective eccentric element of said rotor member, wherein each of said first and second arms has a rest position and an operative position, wherein the respective end portion interferes with said movable electrode to open said switch, and the respective base portion interferes with the respective eccentric element causing a partial rotation of said rotor member, and when a portion of shape memory wire arranged around one of said first and second pulley is powered so that a current flows through this portion overheating, said portion of shape memory wire is retracted and said first or second pulley is rotated so as to cause the rotation of the respective first or second arm, bringing it from said rest position to said operative position, and interfering with the eccentric element to cause the rotation of the rotor member, the other eccentric element of said rotor member being therefore arranged in a position so as to allow the rotation of said rotor member only when the other arm is rotated.

Still according to the invention, each of the first and second arms may further comprise a respective electrical terminal, and the actuator may comprise two return springs, each return spring being electrically coupled with a respective electrical clip, the return springs being arranged to bring the respective first and second arms from the operating position to the rest position.

Advantageously according to the invention, the shape memory wire may have an end coupled to the electric terminal, and one of the return springs may be interposed between the electric clamp of the first arm and the third electrode, and the other return spring is interposed between the electric clamp of the second arm and the first electrode.

According further to the invention, the movable electrode may comprise a protrusion and the rotor member may comprise a pair of cavities arranged such that one of the cavities removably engages with the protrusion of the movable electrode (14) when the rotor member rotates, so as to hold the rotor member in position.

Preferably, according to the present invention, the movable electrode may include a lower laminate and a support coupled to the lower laminate having the protrusion, and the rotor member may include a protrusion on which the cavity is formed.

Always according to the invention, said first and second actuating members may respectively comprise a first and a second slide, each of which can engage with a respective eccentric embossment, wherein said first and second slides may be able to occupy a rest position and an operating position in which they interfere with said movable electrode to open said switch, wherein, when a portion of shape memory wire arranged around one of said first or second slides is supplied with electricity so that a current flows through it overheating, said portion of shape memory wire retracts and said first or second slide moves from said rest position to said operating position and interferes with the respective eccentric element, causing the rotation of said rotor member, the other eccentric element of said rotor member being therefore arranged in a position, so as to allow rotation of the rotor member only when the other slide is moved.

Still according to the invention, each of said first and second sliders may comprise a respective return spring arranged to keep said slider in said rest position.

Advantageously according to the invention, the movable electrode may comprise an embossment and the rotor member may comprise a pair of recesses arranged such that, when the rotor member rotates, one of the recesses removably engages the embossment of the movable electrode to hold the rotor member in position.

According further to the invention, the movable electrode may comprise a lower plate on which the relief is obtained, and the rotor member may comprise a protrusion on which the notch is obtained.

Preferably according to the invention, each of the slides may have a guide along the respective side edge, and the shape-memory wire may pass over both guides of the first and second slides, so that the shape-memory wire, when it is heated, alternately moves the slide from the rest position to the operating position.

Drawings

The present invention will now be described for illustrative but not limitative purposes, according to its preferred embodiments, with particular reference to the various figures of the accompanying drawings, in which:

figure 1 shows an exploded view of a first embodiment of an actuator according to the present invention;

figure 2 shows a top view of the actuator of figure 1 when assembled, with the cover 3 not shown and the actuator in a first operating condition;

figure 3 shows a top view of the actuator of figure 1 when assembled, with the cover 3 not shown and the actuator in a second operating condition;

fig. 4 shows a perspective view of the actuator of fig. 1 from the upper side, in a non-operating state;

FIG. 5 shows a view of the actuator of FIG. 1 along section line A-A;

FIG. 5A illustrates an open bottom view of the actuator of FIG. 1;

figure 6 shows a detail of an actuator according to the invention, in which the switch is open;

figure 7 shows a detail of an actuator according to the invention, in which a projection with a block-shaped recess engages a portion of an electrode;

figure 8 shows an electrical circuit of a switch of the actuator according to the invention;

FIG. 9 shows two electrodes, each coupled to a shape memory wire by crimping;

FIG. 10 shows another view of the two electrodes shown in FIG. 9;

FIG. 11 shows a detail of the shape memory wire of FIG. 9 coupled to an electrode;

figure 12 shows an exploded view of a second embodiment of an actuator according to the present invention;

FIG. 13 illustrates an open plan view of the actuator of FIG. 12;

FIG. 14 illustrates a first cross-sectional view of the actuator of FIG. 12;

FIG. 15 shows a longitudinal cross-sectional view of the actuator of FIG. 12;

FIG. 16 illustrates a second cross-sectional view of the actuator shown in FIG. 12;

FIG. 17 illustrates an open plan view of the actuator of FIG. 12 when in an activated state;

FIG. 18 shows a first detail of FIG. 16;

fig. 19 shows a second detail of fig. 16.

In the various figures, similar components will be denoted by the same reference numerals.

Detailed Description

Looking at actuator a with reference to fig. 1-5, it comprises: a containment case 3 for containing the mechanism of the various elements described below, a shape memory wire 2, a switch SW and a set of electrodes 11, 12, 13, 14, a rotor member 6 and a drive assembly 4, as better described below.

The containment casing 3 has an opening 31 having the shape of a circular arc, the operation of which will be better explained below.

The actuation assembly 41 in the first embodiment comprises an actuation member and in particular a pair of sliders 411 and 412 movable between a rest position and an operating position, each having a guide 413 along a lateral edge.

Furthermore, each slide 411 and 412 has a groove, indicated by the reference numbers 411' and 412 ", respectively.

For each slider 411 and 412 there is provided a respective return spring 5 of the rectilinear type, each inserted in said recess 411' and 412 "and abutting between the containment casing 3 and the respective slider 411 and 412.

The actuator a further comprises three poles 11, 12 and 13 and a further movable pole 14 connected to a terminal board 15 for connecting the actuator a to the control logic of the machine to which it is connected. The movable electrode 14 and the electrode 12 form a switch SW, the operation of which will be better defined below.

The movable electrode 14 also comprises a lower layer 141 having reliefs 142, the operation of which will be better explained below.

The shape memory wire 2 is connected and fixed to the electrode 12 at a first end, connected and fixed to the electrode 13 at an intermediate point and connected and fixed to the electrode 11 at a second end by a clinching method.

The shape memory wire 2 passes over the two guides 413 of the sliders 411 and 412, so that when an electric current flows between the wire portions between the first electrode 11 and the second electrode 12 or between the second electrode 12 and the third electrode 13, the sliders 411 and 412 can be moved appropriately and accordingly, as will be better explained below.

The rotor member 6 comprises a projection 62 with two block-shaped recesses 621, as will be better explained below.

Said rotor member 6 also comprises on the surface a pair of eccentric reliefs 63 by means of which it interferes respectively with said slides 411 and 412 by means of strikes 43 (see also figure 5) placed under the slides 411 and 412 to engage in at least some cases with the eccentric reliefs 63 (see also figure 5A).

Furthermore, said rotor member 6 is pivoted about said containment casing 3 by means of a respective pin 61, and is arranged between two slides 411 and 412 (to which it is coupled by means of said reliefs 63), so that when one of said slides 411 or 412 is activated, it is caused to rotate by a predetermined angle in a direction opposite to that of the other slide, due to the engagement of this slide with said actuator member.

The rotor member 6 also includes two wings 64 which may be connected to or coupled with a driven shaft (not shown) to operate the driven shaft. Thus, when the rotor member 6 is rotated by the slider 411 or 412, it is the wheel to the driven shaft to rotate.

Furthermore, the rotor member 6 is arranged to interact with the switch SW to open the switch SW only when the slides 411 and 412 alternately reach the end of travel, as shown in fig. 2 or 3.

When one of the two sliders 411 and 412 is retracted towards the non-operating position (the non-operating state of the actuator represented in fig. 4) instead after reaching the end of the stroke, the rotor member 6 is arranged to be locked or retained at the end of the rotation caused by each slider 411 or 412 by engaging the notch 621 of the projection 62 with the embossed portion or projection 142 of the lower tier plate 141 of the movable electrode 14.

The operation of the actuator a described above is as follows.

When the actuator a is in the inactive or non-operating position (as in fig. 4), the switch SW is closed, i.e. the movable electrode 14 is in contact with the electrode 12, and there is no power supply for the shape memory wire 2, so it is at room temperature.

When a suitable current is supplied through the terminal board 15, for example, between the electrodes 12 and 13, after a warm-up period, the first portion of the shape-memory wire 2, which connects the electrodes 12 and 13, heats up and retracts due to the effect of the current flowing, causing a movement in the direction of the arrow B of the first slider 411, this movement, overcoming the force opposing the return spring 5, passes from the rest position to the operating position (see figure 2), wherein, at the end of its travel, the first slide opens, by one end, said switch SW (see figure 6), and during its stroke the rotor member 6 is rotated by a preset angle (which in the present embodiment is about 20 °) in the direction of arrow C by means of one of the eccentric reliefs 63 (the one engaging the slider 411), which pushes the slider 411 axially with respect to the wire 2.

Once the switch SW is opened (see fig. 6), the movable electrode 14 is displaced from the electrode 12 from one end of the slider 411 that has reached the end of travel (the moment at which such end of travel is represented in fig. 2).

When the power supply between the electrodes 12 and 13 is interrupted, for example by the control logic of the machine, after a sudden interruption of the voltage due to the separation of the contacts of 12 and 14 (see fig. 6), the first portion of the shape-memory wire 2 starts to cool and retracts, causing the closure of the switch SW (i.e. the return of the movable electrode 14 to contact the electrode 12), the relief 142 of said movable electrode 14 maintaining the engagement with one of the two notches 621 of said projection 62 (see fig. 7).

For this reason, when the slider 411 is retracted to the rest position and for all the time the actuator a remains in this state, the rotor member 6 is maintained in the reached position. In this way, at the end of the cooling phase, the slide 411, which has not been stressed by the shape memory wire 2 which has now been cooled, returns to the rest position thanks to the respective return spring 5.

In order to have a second rotation of the rotor member 6 at the end of the activation, an electric current is made to flow between said electrodes 11 and 12 (for example from the central control unit of the machine on which the actuator a is mounted), so that the second portion of the shape-memory wire 2 is heated, causing the second slider 412 to move, which forces, by overcoming the return force of the respective return spring 5, the rotor 6 to rotate by an angle equal and opposite to the angle of the first activation (see fig. 3), namely 20 °, and to open again said switch SW at the end of the stroke, one end. Since the contacts 11 and 12 are electrically disconnected, the opening signal of the switch SW is detected by the central control unit of the machine in which the actuator a is installed through the terminal board 15.

After interrupting the power supply of the circuit, the portion of wire 2 surrounding slider 412 starts to cool, and slider 412 retracts due to spring 5. Also in this case, the switch SW is closed and at the same time the first activation of the further notch 621 with respect to the projection 62 of the rotor member 6 definitively engages the relief 142 of the lower layer 141 of the movable electrode 14 (see fig. 7).

Thus, the actuator a forms a bistable function. In fact, two successive signals, i.e. one signal between two different pairs of electrodes after the other alternating signal, are required for allowing the generation of the two signals, which in the case in question is caused by the switch SW being open.

Bistable activation is performed by alternately opening the ends of the two slides 411 and 412 only at the moment when the slides reach the end of travel (maximum allowed shortening of the two wire portions 2 around each slide), maintaining the switch SW normally closed.

As can be seen, the actuator a rotates the rotor member 6 in a time-limited and fully mechanical manner.

It is considered that in order to perform a further activation of the shape-memory wire 2 or of a portion thereof, it is necessary to wait for a few seconds for it to cool down, allowing it to return to the rest position by bringing the temperature of the wire to room temperature.

The slides 411 and 412 may be made of metal to allow for faster cooling of the shape memory wire 2.

As can be seen, the shape memory wire 2 is crimped on the electrodes 11, 12 and 13 and in three points to allow optimal operation of the system over time, although a loop such as the above implies continuous mechanical and electrical stress on the shape memory wire 2.

Referring to fig. 9-11, this coupling can be obtained by clinching the two electrodes 11 and the respective shape-memory wire 2.

In particular, the electrode 11 comprises, for example, a first plate 16 and a second plate 17 arranged in superposition, between which the shape memory wire 2 is fixed. The coupling between the first and second plates 16, 17 and the shape memory wire 2 is achieved by means of clinching.

In particular, after the shape memory wire 2 is placed between the first plate 16 and the second plate 17, a die or mold M with an annular groove at the bottom is applied, which is arranged on the second plate 17 and corresponds to the shape memory wire 2.

The punch P is then applied to said first plate 16. The punch P is pressed towards the direction of the die or mould M, thus deforming the surfaces of said sheet 16 and said sheet 17, so that they fit together in the die or mould M and in particular with the internal grooves of said die or mould M. This not only allows the wire to be held between the first and second plates 16, 17, but also achieves an extremely strong and firm mechanical coupling in addition to the electrical coupling.

A second embodiment of an actuator a' according to the invention is observed with reference to figures 12-19.

Also in the present embodiment, the movable electrode 14 and the electrode 12 form a switch SW. Furthermore, said movable electrode 14 comprises a support 143 coupled to the lower layer plate 141, which has a projection 144, the operation of which will be better described hereinafter.

Further, the movable electrode 14 is not in direct contact with the terminal board 15, but there is a blade 14A electrically welded to the movable electrode 14 in the present embodiment, which makes the movable electrode 14 touch the terminal board 15.

In particular, also in this case, the containment casing 3 has an opening 31 which allows two wings 64 to project for driving the shaft on which the actuator is mounted.

The actuation assembly 42 of the actuator a' comprises a first 421 and a second 422 pulley pivoted about respective pins 423 leading to said containment casing 3. The shape memory wire passes around the pulleys 421 and 422.

Also in this case, the two pulleys 421 and 422 can be made of metal to allow a faster cooling of the shape-memory wire 2 when it is heated.

The actuation assembly 42 comprises an actuation member and in particular a first arm 424 and a second arm 425, each pivoting with a respective pin 426 leading to the containment casing 3.

Each of the first and second arms 424, 425 comprises a base portion, respectively 4241 and 4251, shaped so as to interfere, in a better defined way hereinafter, with the eccentric element 63 of the rotor member 6, and end portions 4242 and 4252, which at least partially overlap each other for reasons of space optimization.

Each of the first and second arms 424 and 425 further includes a respective electrical terminal 4243 and 4253.

The actuation assembly 42 also comprises two circular return springs 5', each arranged between the electrodes 13 and 11 and the respective electric clamp 4243 or 4253, respectively.

The return springs 5 'are made of an electrically conductive material to ensure an electrical connection between each of the electrodes 13 and 11, the respective return spring 5', and the respective electrical terminals 4243 and 4253 and thus the shape memory wire 2.

The rotor member 6 pivots about said containment casing 3 by means of respective pins 61 and has: a projection 62; a pair of eccentric reliefs 63, the operation of which will be better explained below; and two wings 64 which transmit the motion to an element (not shown in the figures) driven on the household appliance on which the actuator operates.

The rotor member 6 is rotatable so as to occupy a first operating position and a second operating position.

Furthermore, the projection 62 has a pair of cavities 622 below, arranged such that, when the rotor member 6 rotates and occupies one of said two operating positions, said cavities 622 are removably engaged with said protrusions 144 of said movable electrode 14, so that said rotor member 6 is maintained in position.

The shape memory wire 2, which has its end fixed to an electric clamp 4243 integral with said first arm 424, passes over the first pulley 421 until it reaches the electrode 12 (fig. 13), to which it is fixed by clinching or other equivalent systems known in the art for such wires 2.

The shape memory wire then passes over the second pulley 422 until it reaches the electrical clamp 4253 integral with the second arm 425.

From a functional point of view, the operation of the second embodiment of the actuator a' is substantially similar to that of the first embodiment.

In particular when the actuator a' is in the rest position (fig. 13), the switch SW is closed and the shape memory wire 2 is not powered, and therefore is at room temperature.

When the device or machine in which the actuator a' is installed is activated, a suitable current is supplied between the electrodes 12 and 13 through the terminal board 15.

During a suitable heating time interval, the first portion of the shape-memory wire 2 connecting said electrodes 12 and 13 is heated by the action of the current flowing through the return spring 5 'and the respective electric terminals 4243, made of electrically conductive material as described, so as to retract, causing a rotation of the first pulley 421, which by overcoming the opposite force of the respective return spring 5' causes a clockwise rotation of the arm 424 (see fig. 15), which rotates from the rest position to the operating position, in which it interferes with said movable electrode 14 (see fig. 17) by the respective end portion 4242, thus opening said switch SW.

At the same time, the rotation of said arm 424 interferes with one of the eccentric reliefs 63 of the rotor member 6, causing the latter to rotate by a preset angle until one of the cavities 622 overlaps with the projection 144, holding the rotor member 6 in the reached position, as can be seen in fig. 16 and 18.

Once the switch SW is open then it is possible: the power supply between the electrodes 12 and 13 is interrupted, for example by means of the control logic of the machine.

Thus, the first portion of the shape-memory wire 2 begins to cool and it retracts, causing the switch SW to close, while the rotor member 6 remains in the reached position due to the engagement of the boss 144 formed on the lower layer plate 141 of the movable electrode 14 with one of the cavities 622 (fig. 18) under the projection 62.

In this way, at the end of the cooling phase, the first arm 424 no longer has the stress of the now cooled shape memory wire 2, being returned to the rest position by the respective return spring 5'.

At the same time, switch SW, which is no longer pushed by end portion 4242, is reset and maintained in the closed configuration.

One of the eccentric reliefs 63 is positioned adjacent the other arm 425 (see fig. 15). In this way, if the first arm 424 is activated again, there will be no rotation of the rotor member 6, which will be maintained in the same position by the protrusion 144.

Activation of the second arm 425 by only the feeding electrodes 12 and 11 and thus the second portion of the shape memory wire 2 will rotate the rotor member 6 by a movement similar to the movement described above. In this particular case, the current from the terminal board 15 will reach the movable electrode 14 through the blade 14 a.

As can be seen, also in this case, the actuator a' rotates the rotor member 6 in a bistable and purely mechanical manner.

As can be seen, finally, also in this case, the shape memory wire 2 is crimped onto the electrode 12 and the electrical terminals 4243 and 4253.

The advantages of the invention lie in the following facts: the described mechanism has a completely mechanical bistable operation.

The present invention has been described for purposes of illustration and not limitation in accordance with its preferred embodiments, but it should be understood that: modifications and/or alterations may be introduced by those skilled in the art without departing from the relevant scope as defined in the appended claims.

The claims (modification according to treaty clause 19)

1. An electric actuator (a, a') comprising:

rotor member (6) and

an actuation assembly (4) configured to interfere with the rotor member (6), causing the rotor member to rotate,

wherein the rotor member (6) comprises a pair of eccentric reliefs (63) arranged to interfere with the actuation assembly (4), and

the actuation assembly (4) comprising a shape memory wire (2) and being configured such that when an electric current flows through at least a portion of the shape memory wire (2) a rotation of the rotor member (6) is caused,

it is characterized in that the preparation method is characterized in that,

the electric actuator (A') further includes a movable electrode (14) including a protrusion (144), and

the rotor member (6) comprises a pair of cavities (622) arranged such that one of the cavities (622) removably engages with the protrusion (144) of the movable electrode (14) when the rotor member (6) is rotated so as to hold the rotor member (6) in position.

2. Electric actuator (a, a') according to the preceding claim, characterized in that the actuation assembly (4) is configured to rotate the rotor member (6) alternately in opposite directions.

3. An electric actuator (a, a') according to any of the preceding claims, characterized in that the rotor member (6) is engageable to a member to be moved, such as a driven shaft or the like, so that when the rotor member (6) rotates, a rotational movement is transmitted to the member to be moved.

4. Electric actuator (A, A') according to any of the preceding claims,

the electric actuator includes a Switch (SW), and

the actuation assembly (4) is configured to interfere with the Switch (SW).

5. Electric actuator (A, A') according to the preceding claim, characterized in that it comprises a first electrode (11), a second electrode (12), a third electrode (13) and said movable electrode (14), wherein said second electrode (12) and said movable electrode (14) form said Switch (SW),

wherein one end of the shape memory wire (2) is coupled to the first electrode (11) and the other end is coupled to the third electrode (13), and

wherein the shape memory wire (2) is arranged to assume an electrical coupling with the second electrode (12).

6. Electric actuator (a, a') according to any of the preceding claims, characterized in that the actuation assembly (4) comprises a first and a second actuation member (411, 424, 412, 425) able to interfere in a single direction with the respective eccentric element (63) of the rotor member (6).

7. Electric actuator (a') according to the preceding claim,

the actuating assembly (42) comprises a first pulley (421) and a second pulley (422) around which the shape memory wire (2) is passed, and

the first and second actuation members comprising a first arm (424) and a second arm (425), each arm being rotatable and comprising a respective base portion (4241, 4251) and end portion (4242, 4252), the base portions being shaped so as to interfere with a respective eccentric element (63) of the rotor member (6),

wherein each of said first arm (424) and said second arm (425) has a rest position and an operating position in which the respective end portion (4242, 4252) interferes with said movable electrode (14) to open said Switch (SW) and the respective base portion (4241, 4251) interferes with the respective eccentric element (63) causing the rotor member (6) to partially rotate, and

wherein, when a shape memory wire portion (2) arranged around the first and second pulleys (421, 422) is powered so that an electric current flows through it overheating, said portion of shape memory wire (2) is retracted and the first or second pulley (421, 422) rotates so as to cause a rotation of the respective first or second arm (424, 425), bringing it from the rest position to the operating position and interfering with one eccentric element (63) causing a rotation of the rotor member (6), the other eccentric element (63) of the rotor member (6) being thus arranged in a position such as to allow the rotation of the rotor member (6) only when the other arm (424, 425) rotates.

8. Electric actuator (a') according to the preceding claim,

each of the first and second arms (424, 425) comprises a respective electrical terminal (4243, 4253), and

the electric actuator comprises two return springs (5'), each electrically coupled with a respective electric clamp (4243, 4253), arranged to bring the respective first arm (424) and second arm (425) from the operating position to the rest position.

9. Electric actuator (a') according to the preceding claim,

the shape memory wire (2) has an end coupled to the electrical terminal (4243, 4253), and

one of the return springs (5') is interposed between the third electrode (13) and an electrical clamp (4243) of the first arm (424), and the other return spring (5') is interposed between the first electrode (11) and an electrical clamp (4253) of the second arm (425).

10. Electric actuator (A') according to claim 1,

the movable electrode (14) includes a lower laminate (141) and a support (143) coupled with the lower laminate (141) having the protrusion (144), and

the rotor member (6) includes a protrusion (62) on which the cavity (622) is formed.