Switch with ultra-fast piezoelectric actuators

Abstract

The invention relates to an electrical switch suitable for having a closed configuration and an open configuration, the electrical switch comprising a first contact (2), a second contact (3), a first actuation assembly carrying the first contact (2) and comprising a first piezoelectric actuator (4), a second actuation assembly carrying the second contact (3) and comprising a second piezoelectric actuator (5), each of the first piezoelectric actuator (4) and the second piezoelectric actuator (5) deforming between a retracted state and an elongated state, in particular under the effect of a change in electric field, in a deformation direction (D) substantially collinear with a longitudinal axis (X1, X2) of the piezoelectric actuator (4, 5).

Description

[0001] Description

[0002] TITLE: ULTRA-FAST PIEZOELECTRIC ACTUATOR SWITCH

[0003] TECHNICAL FIELD OF THE INVENTION

[0004]

[0001] The invention relates to the field of electrical equipment enabling the control of a flow of electricity by opening or closing an electrical circuit, thus enabling one or more electrical devices to be switched on or off.

[0005]

[0002] It relates more particularly to a switch comprising one or more contacts carried by one or more piezoelectric actuators.

[0006] STATE OF THE ART

[0007]

[0003] Such a switch generally comprises a fixed contact supported by a bearing and a movable contact supported by a piezoelectric actuator. When an electric field is applied to the piezoelectric actuator, it induces a deformation of the piezoelectric material. This deformation causes the movable contact to move either closer to or further from the fixed contact. This movement allows an electrical circuit to be closed or opened, respectively, and consequently controls the flow of current.

[0008]

[0004] The materials used for the piezoelectric actuator and the support are sensitive to temperature and generally have different coefficients of thermal expansion. These variations, particularly those due to temperature, must be taken into account when maintaining the electrical circuit open or closed. In particular, the contacts must be kept at a sufficient distance from each other in the open configuration to prevent accidental closure, and must remain pressed against each other in the closed configuration to prevent accidental opening.

[0009]

[0005] In other words, the moving contact must be able to be moved between a first position where it is sufficiently far from the fixed contact to avoid accidental closure in case of temperature drift and a second position in which it is pressed against the fixed contact and exerts a certain force on the latter.

[0010]

[0006] To allow this large travel, the switches include a large piezoelectric actuator. However, these switches are somewhat slow to change from one configuration to another because, for a given geometry, the larger a piezoelectric actuator is, the longer its reaction time.

[0011] DESCRIPTION OF THE INVENTION

[0012]

[0007] The invention aims to remedy, at least in part, the drawbacks of the prior art, and more particularly to provide a switch of a similar type, capable of switching from one configuration to another very quickly, for example in less than 30 seconds, while remaining reliable.

[0008] To this end, the invention relates to an electrical switch adapted to have a closed configuration and an open configuration, comprising:

[0013] - an initial contact,

[0014] - a second contact,

[0015] - a first actuation assembly carrying the first contact and comprising a first piezoelectric actuator,

[0016] - a second actuation assembly carrying the second contact and comprising a second piezoelectric actuator, each of the first piezoelectric actuator and the second piezoelectric actuator deforming, under the effect of a change in electric field and / or a variation of an operational parameter specific to the actuator or its surrounding environment, such as fatigue, ambient temperature or ambient humidity, along a deformation direction substantially collinear with a longitudinal axis of the piezoelectric actuator, between a retracted state and an extended state, the first actuation assembly and the second actuation assembly extending in the same general plane of extension and being configured so that, when the first piezoelectric actuator and the second piezoelectric actuator are subjected to the same variation of an operational parameter, the configuration in which the switch is located is maintained,while the deformation under the effect of a change in the electric field of one or both of the piezoelectric actuators causes the switch to change from one configuration to the other, where the closed configuration corresponds to contact between the first and second contacts, and where the open configuration corresponds to the absence of contact between the first and second contacts.

[0017]

[0009] Thanks to the configuration of the actuation assemblies which allows the switch to be maintained in the configuration in which it is located, in response to a drift due in particular to temperature or fatigue, i.e. in an involuntary manner (i.e. without the application of an electrical signal to actuation the switch), it is possible to arrange the actuation assemblies so that, in the open configuration of the switch, the distance between the contacts is very small, which makes it possible to limit the movement of the piezoelectric actuator(s), and thus to limit the time of transition from one configuration to another.

[0018]

[0010] Furthermore, thanks to the elongational deformation of the piezoelectric actuators, the switch exhibits a high resonant frequency, resulting in a short response time. This is because this deformation involves a coordinated movement of the entire piezoelectric material without significant curvature, and a high rigidity of the piezoelectric actuator. Thus, the speed at which each piezoelectric actuator deforms to change state is very rapid.

[0019]

[0011] Consequently, the combination of the actuation assembly arrangement with the use of longitudinally deforming piezoelectric actuators allows for a very rapid and reliable transition from one configuration to another when a change in the electric field is (intentionally) applied to one or both of the piezoelectric actuators.

[0012] Some preferred, but not limiting, aspects of this assembly are as follows.

[0020]

[0013] The first piezoelectric actuator and the second piezoelectric actuator can be made of one or the same materials.

[0021]

[0014] The first piezoelectric actuator and the second piezoelectric actuator can extend parallel to each other.

[0022]

[0015] The second actuation assembly may include a third piezoelectric actuator having a first end mechanically assembled to the first piezoelectric actuator and a second end, opposite to the first end, mechanically assembled to the second piezoelectric actuator.

[0023]

[0016] The first piezoelectric actuator may have a first end mechanically assembled to the first end of the third piezoelectric actuator and a second end, opposite to the first end, bearing the first contact, the second piezoelectric actuator having an end mechanically assembled to the first end of the first piezoelectric actuator.

[0024]

[0017] The switch may have a first plane of symmetry which divides the first piezoelectric actuator along its length and which is perpendicular to the general plane of extension and / or a second plane of symmetry which passes between the first and second piezoelectric actuators and through the center of the third piezoelectric actuator and which is perpendicular to both the general plane of extension and the longitudinal axes of the piezoelectric actuators.

[0025]

[0018] The second actuation assembly may further comprise a first intermediate piezoelectric actuator and a second intermediate piezoelectric actuator, the first and second intermediate piezoelectric actuators being made of the same material and having substantially identical dimensions, the first and second intermediate piezoelectric actuators being disposed between the first piezoelectric actuator and the second piezoelectric actuator, the first intermediate piezoelectric actuator having a first end mechanically assembled to the first end of the second actuator and a second end, opposite the first end, the second intermediate piezoelectric actuator having a first end mechanically assembled to the first end of the first piezoelectric actuator and a second end, opposite the first end,mechanically assembled at the second end of the first intermediate piezoelectric actuator.

[0026]

[0019] The second actuation assembly may further comprise a third intermediate piezoelectric actuator and a fourth intermediate piezoelectric actuator, the third and fourth intermediate piezoelectric actuators being arranged substantially symmetrically to the first and second intermediate piezoelectric actuators with respect to a plane of symmetry that bisects the first piezoelectric actuator lengthwise and is perpendicular to the general plane of extension.

[0020] The distance between the first and second contacts when the switch is in the open configuration may be between 0.00002 and 0.005 times the length of one of the first and second piezoelectric actuators.

[0027]

[0021] The second actuation assembly may include a support arm carrying the second contact, the support arm being fixed to the second end of the second piezoelectric actuator and to the second end of the third piezoelectric actuator.

[0028]

[0022] The first piezoelectric actuator can be arranged between the second piezoelectric actuator and the third piezoelectric actuator.

[0029]

[0023] The first piezoelectric actuator, the second piezoelectric actuator and the third piezoelectric actuator may have substantially the same length.

[0030]

[0024] The second piezoelectric actuator may have a first end mechanically assembled to the second end of the third piezoelectric actuator and a second end, opposite to the first end, carrying the second contact.

[0031]

[0025] The third piezoelectric actuator can have a length substantially equal to the sum of the length of the first piezoelectric actuator and the length of the second piezoelectric actuator.

[0032]

[0026] The first contact and the second contact can be moved in a direction parallel to the direction of deformation when the piezoelectric actuators are deformed between the retracted state and the elongated state.

[0033]

[0027] Switch according to any one of claims 1 and 2, wherein the contacts are moved in a direction perpendicular to the direction of deformation (D) when the piezoelectric actuators (4, 5) are deformed between the retracted state and the elongated state.

[0034]

[0028] The first actuation assembly may include a first amplifying structure and the second actuation assembly includes a second amplifying structure, the first amplifying structure being mechanically assembled on the first piezoelectric actuator and carrying the first contact, the second amplifying structure being mechanically assembled on the second piezoelectric actuator and carrying the second contact.

[0035]

[0029] The longitudinal axes of the first and second piezoelectric actuators can be at a distance from each other of less than four times, preferably less than ten times, the length of the first piezoelectric actuator or the second piezoelectric actuator.

[0036]

[0030] Each of the piezoelectric actuators being able to deform substantially symmetrically with respect to a plane of symmetry perpendicular to the direction of deformation, the switch comprising a base configured to keep the actuation assemblies away from an operating surface, at least one of the actuators resting on the base so that the direction of deformation is substantially parallel to the operating surface and the plane of symmetry of said piezoelectric actuator passes through the base.

[0037] BRIEF DESCRIPTION OF THE FIGURES

[0038]

[0031] Other advantages, purposes and special features of the present invention will become apparent from the following non-limiting description of at least one particular embodiment of the devices and methods of the present invention, with reference to the accompanying drawings.

[0039]

[0032] Figure 1, Figure 2, Figure 3, Figure 4 and Figure 5 schematically and partially represent a switch according to a first embodiment of the invention.

[0040]

[0033] Figure 6 schematically and partially represents, in perspective view, a switch according to a second embodiment of the invention.

[0041]

[0034] Figure 7 schematically and partially represents, according to an exploded plan view, a variant of the switch of Figure 6.

[0042]

[0035] Figure 8 and Figure 9 schematically and partially represent a switch according to a third embodiment of the invention.

[0043]

[0036] Figure 10, Figure 11, Figure 12, Figure 13 and Figure 14 schematically and partially represent a switch according to a fourth embodiment of the invention.

[0044]

[0037] Figure 15 schematically and partially represents, in perspective view, a switch according to a fifth embodiment of the invention.

[0045]

[0038] Figure 16 schematically and partially represents, from a perspective view, a first variant of the switch of Figure 15.

[0046]

[0039] Figure 17 schematically and partially represents, in perspective view, a second variant of the switch of Figure 15.

[0047]

[0040] Figure 18, Figure 19, Figure 20, Figure 21 and Figure 22 schematically and partially represent a switch according to a sixth embodiment of the invention.

[0048]

[0041] Figure 23, Figure 24 and Figure 25 show schematic and partial examples of contacts.

[0049] DETAILED DESCRIPTION OF THE INVENTION

[0050]

[0042] The invention relates to an electrical switch that allows for very rapid switching from an open configuration, where the contacts are separated, to a closed configuration, where the contacts touch, or vice versa, while remaining reliable.

[0051]

[0043] To achieve this, the switch includes in particular two actuation assemblies, each carrying one of the contacts and comprising one or more piezoelectric actuators.

[0052]

[0044] It is recalled that a piezoelectric actuator is a device that converts electrical energy into mechanical motion thanks to the properties of piezoelectric materials.

[0045] In practice, a piezoelectric actuator comprises a rod made of piezoelectric material and at least two electrodes configured to apply an electric field to the rod made of piezoelectric material.

[0053]

[0046] A piezoelectric actuator typically comprises a stack of the rod made of piezoelectric material and the two electrodes, in which said rod is located between the electrodes.

[0054]

[0047] It should be noted that the deformation of the piezoelectric actuator is influenced, in particular, by the direction of the polarization of the piezoelectric material with respect to the applied electric field. It is therefore practically possible to reverse the polarities of the electrodes to obtain reversed deformations by applying the same electric field.

[0055]

[0048] In the present invention, each piezoelectric actuator extends or retracts (deforms) when a change in the electric field is applied. This deformation allows the switch to move from one configuration (open or closed) to the other by moving a contact.

[0056]

[0049] In addition, each piezoelectric actuator lengthens or retracts (deforms) when an operational parameter specific to the actuator or its surrounding environment is varied, such as fatigue, ambient temperature or ambient humidity, and this independently of the change in the applied electric field, and more generally of the applied electric field.

[0057]

[0050] In concrete terms, each piezoelectric actuator deforms along a direction of deformation substantially collinear with the longitudinal axis of said piezoelectric actuator between a retracted state and an elongated state, in which its length is increased compared to the retracted state.

[0058]

[0051] By "substantially collinear," it is understood that the longitudinal axis of the piezoelectric actuator forms an angle of 15° or less, preferably 5° or less, with the direction of deformation. The deformation therefore occurs essentially along the longitudinal axis of the piezoelectric actuator, and can thus be described as longitudinal or by elongation / contraction.

[0059]

[0052] The invention, according to its various embodiments, thus aims at an electrical switch comprising a first contact, a second contact, a first actuation assembly carrying the first contact and comprising a first piezoelectric actuator, and a second actuation assembly carrying the second contact and comprising a second piezoelectric actuator.

[0060]

[0053] Preferably, the first piezoelectric actuator and the second piezoelectric actuator are made of one or more identical materials.

[0061]

[0054] As previously stated, each of the first piezoelectric actuator and the second piezoelectric actuator deforms, under the effect of a change in the electric field and / or a variation of an operational parameter specific to the actuator or its surrounding environment, such as fatigue, ambient temperature or ambient humidity, along a deformation direction substantially collinear with a longitudinal axis of the piezoelectric actuator, between a retracted state and an elongated state.

[0055] The first actuation set and the second actuation set extend in the same general plane of extension and are configured so that, when the first piezoelectric actuator and the second piezoelectric actuator are subjected to the same variation of an operational parameter, the configuration in which the switch is located is maintained (conserved), while the deformation under the effect of a change in the electric field of one and / or the other of the piezoelectric actuators causes the switch to move from one configuration to the other.

[0062]

[0056] The closed configuration corresponds to contact between the first and second contacts, while the open configuration corresponds to the absence of contact between the first and second contacts.

[0063]

[0057] Figures 1 to 5 show a switch 1 according to a first embodiment. The switch 1 has a first contact 2 and a second contact 3, each of which is intended to be electrically connected to an electrical circuit or to a part of an electrical circuit (not shown).

[0064]

[0058] The switch 1 is configured to admit an open configuration, as illustrated in Figures 1 to 4, in which the first contact 2 and the second contact 3 are at a distance from each other, for example to open an electrical circuit, and a closed configuration, as illustrated in Figure 5, in which the first contact 2 and the second contact 3 are in contact, for example to close an electrical circuit.

[0065]

[0059] The switch 1 further comprises a first piezoelectric actuator 4 carrying the first contact 2 and a second piezoelectric actuator 5 carrying the second contact 3. The first piezoelectric actuator 4 here forms a first actuation set while the second piezoelectric actuator 5 here forms a second actuation set.

[0066]

[0060] The first piezoelectric actuator 4 and the second piezoelectric actuator 5 are configured to move the first contact 2 and the second contact 3 respectively by deforming longitudinally.

[0067]

[0061] Each piezoelectric actuator 4, 5 comprises a rod of piezoelectric material extending along a longitudinal axis X4, X5. It further comprises electrodes (not shown) configured to apply an electric field to the rod of piezoelectric material.

[0068]

[0062] The first piezoelectric actuator 4 and the second piezoelectric actuator 5 are made of one or more identical materials.

[0069]

[0063] The first piezoelectric actuator 4 and the second piezoelectric actuator 5 are also of substantially identical cross-section. In this document, "substantially identical" means that the difference in cross-section is less than or equal to 20% of the larger cross-section of the first and second piezoelectric actuators.

[0070]

[0064] The deformation of each of the first and second piezoelectric actuators 4, 5 can be induced: either intentionally when the switch is actuation, i.e., by a change in the electric field applied by the electrodes; or involuntarily, for example, by a variation in an operational parameter specific to the actuator or its surrounding environment (also called drift), such as temperature, humidity, or other environmental variations, or even aging, causing drift. For the sake of brevity, the following will simply refer to a variation in an operational parameter or to drift.

[0071]

[0065] A first end 6 of the first piezoelectric actuator 4 is mechanically assembled to a first end 7 of the second piezoelectric actuator 5, by means of a connecting means 8, so that the piezoelectric actuators 4, 5 extend side by side and parallel to each other.

[0072]

[0066] The first end 6 of the first piezoelectric actuator 4 is aligned with the first end 7 of the second piezoelectric actuator 5 in a direction perpendicular to the longitudinal axes X4, X5 of the piezoelectric actuators 4, 5.

[0073]

[0067] A second end 9 of the first piezoelectric actuator 4, opposite the first end 6, and a second end 10 of the second piezoelectric actuator 5, opposite the first end 7, are thus moved in the same direction when the piezoelectric actuators 4, 5 extend or retract simultaneously, which occurs in particular during a variation of an operational parameter (unintentional deformation) as indicated previously.

[0074]

[0068] The first contact 2 is fixed to the second end 9 of the first piezoelectric actuator 4 and the second contact 3 is fixed to a support arm 12, itself fixed to the second end 10 of the second piezoelectric actuator 5. The support arm 12 is configured to hold the second contact 3 opposite the first contact 2, so that they are aligned along the deformation direction D of the piezoelectric actuators 4, 5.

[0075]

[0069] The configuration in which the switch 1 is located is then maintained (preserved) in the event of a variation of an operational parameter (unintentional deformation), given that the piezoelectric actuators 4, 5 deform in the same way along a deformation direction D which is parallel with the alignment direction of the contacts 2, 3. In other words, the relative position of the contacts 2, 3 with respect to each other remains substantially identical when the piezoelectric actuators 5, 6 deform in the same way, for example in the event of drift.

[0076]

[0070] The support arm 12 can be made of a different material than that of the piezoelectric actuators 4, 5. For example, the support arm 12 can be made of a material with a low coefficient of thermal expansion, such as polyetheretherketone (PEEK). The support arm 12 is thus relatively insensitive to variations in temperature and humidity. Alternatively, the support arm is made of the same piezoelectric material as the piezoelectric actuators. In this case, the support arm is used as a passive element and is not subjected to an electric field.

[0071] As is particularly evident in Figure 1, the switch 1 defines a general extension plane P. Due to their longitudinal deformation, the piezoelectric actuators 4, 5 remain substantially within the general extension plane P in both their retracted and extended states.The switch 1 thus remains globally flat, whether the piezoelectric actuators 4, 5 deform or not.

[0077]

[0072] In the example shown, the switch 1 has a base 13 configured to keep the piezoelectric actuators 4, 5 away from a surface S, shown partially in Figure 1, in order to limit friction on this surface S during the deformation of the piezoelectric actuators 4, 5.

[0078]

[0073] Since the piezoelectric actuators 4, 5 remain substantially in the general extension plane P, the base 13 can be designed to maintain the piezoelectric actuators 4, 5 at a relatively small distance from the surface S. In other words, the base 13 can have a relatively small height, the height being defined along a direction perpendicular to the general extension plane P of the switch. In the example shown, the general extension plane P of the switch 1 is substantially parallel to the surface S.

[0079]

[0074] It should be noted that Figures 2 to 5 illustrate switch 1 from a top view. However, they could also illustrate switch 1 from a side view. In particular, switch 1 could be rotated 90° around the longitudinal axis of the second piezoelectric actuator so that the general plane of extension is perpendicular to the surface.

[0080]

[0075] Each piezoelectric actuator 4, 5 deforms substantially symmetrically with respect to a plane of symmetry passing through its center and perpendicular to its longitudinal axis. By "substantially symmetrical", it is understood that the plane of symmetry is located in a central area covering less than 30%, preferably less than 10%, of the length of the piezoelectric actuator.

[0081]

[0076] The piezoelectric actuators 4, 5 thus deform substantially symmetrically with respect to their center of gravity, which is located in a central area of ​​the piezoelectric actuator 4, 5 extending over a length less than 30%, preferably less than 10%, of the length of the piezoelectric actuator.

[0082]

[0077] The base 13 is thus advantageously in contact with a central area of ​​the second piezoelectric actuator 5 in order to limit the transmission of vibrations to the base 13 and to improve the movement speed of the first and second piezoelectric actuators 4, 5. In other words, a central area of ​​the second piezoelectric actuator 5 rests on the base 13, while the first piezoelectric actuator 4 and the remainder of the second piezoelectric actuator 5 are suspended in equilibrium above the surface S. By way of example, the central area represents less than 20%, advantageously less than 10%, of the length of the second piezoelectric actuator. This allows for the transfer of a minimum of mechanical deformation energy to the base 13.

[0083]

[0078] The base 13 also has a lower Young's modulus than the second piezoelectric actuator, in order to limit the mechanical deformation energy transmitted to the base.

[0079] In particular, the base 13 is in contact with the second piezoelectric actuator 5 near a vibration node in the principal resonance mode of this piezoelectric actuator. Since the displacement of such a piezoelectric actuator is minimal near such a node, the vibration forces transmitted to the base 13 are minimal. This thus reduces the mechanical stresses on the base 13.

[0084]

[0080] Due to its longitudinal and substantially symmetrical deformation, the second piezoelectric actuator 5 maintains its center of gravity in a substantially constant position and generates little or no moment capable of generating a force on the base 13. Also, the displacements take place almost exclusively in the general extension plane P, which limits imbalances or torsional moments capable of generating stresses in the base 13.

[0085]

[0081] Furthermore, the first and second piezoelectric actuators 4, 5 are arranged relative to each other such that the centers of gravity of these piezoelectric actuators 4, 5 are at a distance less than four times, preferably less than ten times, the length of the first piezoelectric actuator 4 or the second piezoelectric actuator 5. In other words, the longitudinal axes X4, X5 of the first and second piezoelectric actuators 4, 5 are at a distance from each other less than four times, preferably less than ten times, the length of the first piezoelectric actuator 4 or the second piezoelectric actuator 5.

[0086]

[0082] This reduces the bending torque at the interface between the piezoelectric actuators 4, 5, here at the level of the connecting means 8, between actuators. Furthermore, this limits the excitation of low-frequency bending resonance modes, thereby reducing bending separation forces in favor of shear forces.

[0087]

[0083] The first piezoelectric actuator 4 can then simply be placed on the base 13, without being firmly fixed to it, as is the case in the example shown. This allows the first piezoelectric actuator 4 to move more freely and quickly, because there are no parasitic resistive forces coming from the base 13.

[0088]

[0084] In an unillustrated embodiment, the base is provided with a guiding means, such as a groove, adapted to receive the second piezoelectric actuator via a sliding connection. In another unillustrated embodiment, the base is provided with a housing adapted to receive a portion of the second piezoelectric actuator and a snap-fit ​​means configured to retain the portion of the second piezoelectric actuator in the housing.

[0089]

[0085] Generally, a first switch configuration, for example the closed configuration, is obtained by applying a first electric field to the first piezoelectric actuator and a second electric field to the second piezoelectric actuator. The second switch configuration, for example the open configuration, is obtained by applying to the first and / or second piezoelectric actuator an electric field different from the electric field applied during the first configuration.

[0086] It should be noted, as indicated above, that the expression "application of an electric field" does not exclude the possibility that this electric field is zero. Thus, in a particular case, a switch configuration is obtained by applying a zero electric field to each piezoelectric actuator.

[0090]

[0087] In this configuration, known as the resting state, shown in Figure 2, the piezoelectric actuators 4, 5 are in an intermediate state, also called the resting state, between the retracted and extended states. Depending on the application of the switch, the default configuration corresponds either to the closed configuration, for example when the switch is used in a circuit breaker, or to the open configuration.

[0091]

[0088] The examples described below present a switch configured to admit an open configuration, in which the contacts are separated from each other, when a zero electric field is applied to each of the piezoelectric actuators. In other words, the switch has an open configuration as its default. Of course, the invention is not limited to a switch having such a default configuration, and the switch could also have a closed configuration as its default. Furthermore, the switch could also admit a closed configuration when the actuators are subjected to a first non-zero electric field, and an open configuration when the actuators are subjected to a second non-zero electric field, different from the first electric field.

[0092]

[0089] It should also be noted that, in the figures, the difference in length of the piezoelectric actuators is exaggerated in order to clearly show the space between the contacts in the open configuration of the switch. In practice, the difference in length of the actuators can be on the order of a micrometer.

[0093]

[0090] With reference to Figure 2, in the resting configuration of switch 1, the piezoelectric actuators are of substantially the same length. The length of the piezoelectric actuators 4, 5 is defined along their longitudinal axis.

[0094]

[0091] In this document, "substantially identical" means that the difference in length between the first and second piezoelectric actuators 4, 5 is less than or equal to 20% of the length of the longer piezoelectric actuator.

[0095]

[0092] It should be noted, however, that the variation in length, for example on the order of a few micrometers, is very small compared to the length of the piezoelectric actuators. In fact, the piezoelectric actuators are of identical length not only in the resting configuration, but more generally in any configuration, regardless of the state of the actuators.

[0096]

[0093] The distance between the first end 6 of the first piezoelectric actuator 4 and the first contact 2, denoted here d4, is less than the distance between the first end 7 of the second piezoelectric actuator 5 and the second contact 3, denoted here d5. The difference between the distances d4 and d5 corresponds to the distance separating the first contact 2 from the second contact 3, which is commonly referred to as the "air gap" and is denoted here e. Thus, when the piezoelectric actuators 4, 5 are at rest, the switch 1 is configured here to satisfy the following inequality: d5 - d4 = e > 0.

[0097]

[0094] In Figure 3, the piezoelectric actuators 4 and 5 are both in their retracted state, under the effect of a first predetermined electric field. The distance between the first end 6 of the first piezoelectric actuator 4 and the first contact 2, denoted d 4R, is here less than the distance d4. Similarly, the distance between the first end 7 of the second piezoelectric actuator 5 and the second contact 3, denoted d5R, is here less than the distance d5.

[0098]

[0095] In Figure 4, the piezoelectric actuators 4 and 5 are both in their extended state, under the influence of a second predetermined electric field. The distance between the first end 6 of the first piezoelectric actuator 4 and the first contact 2, denoted d4, is greater than the distance d4. Similarly, the distance between the first end 7 of the second piezoelectric actuator 5 and the second contact 3, denoted d 5A , is here greater than the distance d5.

[0099]

[0096] Since the piezoelectric actuators 4, 5 are made of one or more identical materials and are of substantially identical length, they deform in substantially identical ways in response to drift. Thus, in the presence of drift, the first and second piezoelectric actuators 4, 5 retract or extend in substantially identical ways, and the configuration of the switch is maintained.

[0100]

[0097] Denoting L4 as the length of the first piezoelectric actuator 4 in its rest state and L5 as the length of the second piezoelectric actuator 5 in its rest state, and defining a value a corresponding to the rate of change in the length of the piezoelectric actuators under the effect of temperature, humidity, or aging, the modified lengths can be written as follows: L4m = aL4 and L5m = aL5. The modified value of the air gap can also be written as follows: em = e + aL5 - aL4 = e + a(L5 - L4). Thus, since the piezoelectric actuators 4 and 5 are substantially the same length, the contacts 2 and 3 maintain an unchanged relative position, which eliminates the risk of accidental opening or closing in the event of drift.

[0101]

[0098] To switch the switch 1 from its open to its closed position, the first piezoelectric actuator 4 must be placed in its extended state and / or the second piezoelectric actuator 5 in its retracted state. To do this, the electric field applied to the first piezoelectric actuator 4 and / or the second piezoelectric actuator 5 is modified.

[0102]

[0099] In the open configuration, each piezoelectric actuator 4, 5 is subjected to an electric field that may or may not be zero. Changing one or both of the electric fields, through the deliberate application of an electrical signal, leads to the switch moving to the closed configuration.

[0100] In the example illustrated in Figure 5, an electric field is applied to the first piezoelectric actuator 4 to move it into its extended state, and an electric field is applied to the second piezoelectric actuator 5 to move it into its retracted state.

[0103]

[0101] By configuring the piezoelectric actuators 4, 5 so that the distance d4 or d 4Ais greater than the distance d5 or d5R, a contact force is generated at the interface between the first contact 2 and the second contact 3, which ensures a more stable electrical connection, reduces electrical resistance and allows the passage of relatively high currents.

[0104]

[0102] The same principle applies to switching switch 1 from its closed configuration to its open configuration.

[0105]

[0103] More generally, due to the longitudinal deformation of the piezoelectric actuators 4, 5, the opening or closing of the switch 1 is very rapid because the piezoelectric actuators 4, 5 are rigid and have a high resonant frequency and a very short response time. Furthermore, they are arranged to extend and retract in parallel, which optimizes their efficiency.

[0106]

[0104] In addition, since the switch 1 makes it possible to keep the relative position of the contacts 2, 3 substantially constant, it is possible to arrange the electric actuators 4, 5 so that, in the open configuration of the switch 1, the distance between the contacts is very small, which makes it possible to limit the movement of the piezoelectric actuator(s), and thus to limit the time of transition from one configuration to the other.

[0107]

[0105] In particular, the distance between the first contact 2 and the second contact 3 when the switch 1 is in the open configuration is between 0.00002 and 0.005 times the length of one of the first and second piezoelectric actuators 4, 5.

[0108]

[0106] Thus, thanks to the longitudinal deformation of the piezoelectric actuators 4, 5 and the small distance between the contacts 2, 3, the switch 1 is able to achieve very short closing or opening times, for example less than 30 ps.

[0109]

[0107] Figure 6 shows a switch according to a second embodiment. This switch differs structurally from that of the first embodiment in that the second actuation assembly includes an additional piezoelectric actuator, hereinafter referred to as the third piezoelectric actuator. For the sake of simplicity, the same reference numerals have therefore been used, except for the switch, for which a similar reference numeral, but with the addition of the number 100, has been used.

[0110]

[0108] In this switch 101, the third piezoelectric actuator 15 is identical to the second piezoelectric actuator 5. In other words, all the piezoelectric actuators 4, 5, 15 are of substantially identical length, and here also of section.

[0111]

[0109] The switch 101 has a first end 16 mechanically assembled to the first end 6 of the first piezoelectric actuator 4 and a second end 17 opposite to the first end 16, mechanically assembled to the support arm 12. The piezoelectric actuators 4, 5, 15 are here mechanically assembled together by means of connecting means 8, here of which there are two.

[0112]

[0110] The first ends 6, 7, 16 of the piezoelectric actuators 4, 5, 15 are aligned in a direction perpendicular to the longitudinal axes of the piezoelectric actuators 4, 5, 15.

[0113]

[0111] The first piezoelectric actuator 4 extends between the second and third piezoelectric actuators 5, 15. The switch 101 has a plane of symmetry P sy mi which divides the first piezoelectric actuator 4 along its length and which is perpendicular to the general extension plane P.

[0114]

[0112] In the example shown, the switch 101 further includes an additional (not visible) base configured, with the base 13, to keep the piezoelectric actuators 4, 5, 15 at a distance from the surface S, partially shown in Figure 6, in order to limit friction on the surface S during the deformation of the piezoelectric actuators 4, 5, 15. The additional base is in contact with a central area of ​​the third piezoelectric actuator 15. For example, it is arranged symmetrically to the base 13 with respect to the plane of symmetry P sy mid.

[0115]

[0113] Furthermore, the first and third piezoelectric actuators 4, 15 are arranged relative to each other such that the centers of gravity of these piezoelectric actuators 4, 15 are at a distance less than four times, preferably less than ten times, the length of the first piezoelectric actuator 4 or the third piezoelectric actuator 15. In other words, the longitudinal axes X4, Xi5 of the first and third piezoelectric actuators 4, 15 are at a distance from each other less than four times, preferably less than ten times, the length of the first piezoelectric actuator 4 or the third piezoelectric actuator 15. The same applies to the distance between the longitudinal axes X5, Xi5 of the second and third piezoelectric actuators 5, 15.

[0116]

[0114] In an unrepresented variant, the second and third actuators 5, 15 have a substantially identical cross-section, while the first actuator 4 has a cross-section approximately twice as large as the cross-section of the second and third actuators 5 and 15.

[0117]

[0115] In an alternative embodiment not shown, the switch further comprises sliding guide rings mounted between the first piezoelectric actuator and the second and third actuators, configured to maintain the first electric actuator equidistant from the second and third piezoelectric actuators. These guide rings are, for example, made of a material that is flexible relative to the piezoelectric material of the piezoelectric actuators. This material is, for example, also electrically insulating. It could, for example, be a plastic material.

[0118]

[0116] Since the piezoelectric actuators 4, 5, 15 are made of one or more identical materials and are of substantially identical length, they deform in substantially identical ways in response to drift. Thus, the switch 101 according to the second embodiment reacts in the same way to variations in temperature and / or humidity conditions as the switch 1 according to the first embodiment.

[0119]

[0117] To switch the switch 101 from its open configuration to its closed configuration, or vice versa, the same process is applied as that described with reference to the switch 1 according to the first embodiment, by actuating the second and third piezoelectric actuators 5, 15 in the same way.

[0120]

[0118] In addition to the advantages related to switch 1 according to the first embodiment, this switch 101 has better mechanical robustness.

[0121]

[0119] In particular, when contacts 2, 3 are pressed against each other, the first piezoelectric actuator 4 exerts a force that tends to move its first end 6 away from the second contact 3 fixed to the support arm, while the second and third piezoelectric actuators exert forces that tend to move their first end closer to the support arm. Due to the symmetry, the resultant of the forces generated by the second and third piezoelectric actuators 5, 15 is collinear and opposite to the force generated by the first piezoelectric actuator 4, which limits, or even eliminates, the occurrence of torsional torques in the piezoelectric actuators 4, 5, 15. This remains valid even during dynamic deformation phases, namely acceleration or deceleration. This makes it possible to limit the excitation of a low-frequency resonance mode linked to bending modes in the switch.This also prevents separation forces from being exerted between the connecting means 8 and the piezoelectric actuators 4, 5, 15.

[0122]

[0120] In an alternative embodiment not shown, the switch lacks connecting means and the piezoelectric actuators are mechanically bonded together. This is possible because bonded assembly is relatively resistant to shear forces but much less so to bending forces.

[0123]

[0121] In addition, the support arm 12 is more stable, as it is held by both the second piezoelectric actuator 5 and the third piezoelectric actuator 15. The second contact 3 is therefore even less likely to accidentally move closer to or further away from the first contact 2, which further improves the reliability of the switch 101.

[0124]

[0122] Figure 7 shows a variant of the switch according to the second embodiment. This switch is functionally similar to that of the second embodiment, but differs structurally in that it has an arrangement allowing for even more precise adjustment of the distance between the contacts. For the sake of simplicity, the same numerical references have therefore been used.

[0125]

[0123] In this switch 101, the second and third piezoelectric actuators 5, 15 each have a rectifier tip 22 fixed to their respective second end. The rectifier tips 22 each have a first bearing surface 23 intended to be opposite the support arm 12. The first bearing surfaces 23 and the first contact 2 are aligned, i.e., contained in the same plane, here a plane perpendicular to the general extension plane P.

[0126]

[0124] The support arm 12 has second bearing surfaces 25, each being provided to be opposite a first bearing surface 23 of a grinding tip 22. The second bearing surfaces 25 and the second contact 3 are aligned, that is to say included in the same plane, here perpendicular to the general extension plane P.

[0127]

[0125] In the example shown, the switch 101 further comprises spacers 26 arranged between the first bearing surfaces 23 and the second bearing surfaces 25, so as to maintain the first contact 2 and the second contact 3 at a predefined distance from each other, corresponding to a thickness of the spacers 26, at least when the piezoelectric actuators are in the same state. It is therefore possible to adjust the distance between the contacts 2, 3 very precisely simply by adapting the thickness of the spacers 26.

[0128]

[0126] In the example shown, the grinding tips 22, the spacers 26, and the support arm 12 are provided with holes adapted for the passage of screws 27 to fasten them together. Other fastening methods can of course be considered, but screws or other similar means have the advantage of not requiring the addition of material between the different parts, such as glue, which allows for high precision in adjusting the air gap. This also has the advantage of guaranteeing and maintaining very good alignment of the different parts, and in particular of the contacts 2, 3.

[0129]

[0127] To obtain such alignment, the first bearing surfaces 23 and the first contact 2 as well as the second bearing surfaces 25 and the second contact are for example rectified.

[0130]

[0128] For example, the first bearing surfaces 23 and the first contact 2 can be rectified while the piezoelectric actuators 4, 5, 15 are in the same state.

[0131]

[0129] For example, the first bearing surfaces 23 and the first contact 2 can be rectified while the first piezoelectric actuator 4 is in a given state and the second and third piezoelectric actuators 5, 15 are in a different given state. In this case, the air gap appears when all the piezoelectric actuators 4, 5, 16 are moved into the same state. In this example, not shown, the use of spacers is not necessary.

[0132]

[0130] In an unrepresented variant, the switch further comprises guide rings, as described with reference to the second embodiment.

[0133]

[0131] In another embodiment not shown, the second contact 3 is fixed to the support arm 12 by means of an intermediate fastener, such as a screw or a rivet. A spacer, for example a shim or a washer, is placed between the intermediate fastener and the support arm 12 to adjust the distance between the contacts 2, 3. The support arm 12 may have a recess adapted to receive the intermediate fastener so that it is flush.

[0134]

[0132] Figures 8 and 9 show a switch according to a third embodiment. This switch is functionally similar to that of the second embodiment, but differs structurally in that the second actuation assembly further comprises intermediate piezoelectric actuators arranged between the first and second piezoelectric actuators and between the first and third piezoelectric actuators. For the sake of simplicity, the same reference numerals have therefore been used.

[0135]

[0133] The intermediate piezoelectric actuators, here of which there are four, are distributed in pairs, namely a first pair arranged between the first piezoelectric actuator 4 and the second piezoelectric actuator 5 and a second pair arranged between the first piezoelectric actuator 4 and the third piezoelectric actuator 15, as can be seen in Figure 8.

[0136]

[0134] The first pair comprises a first intermediate piezoelectric actuator 31 and a second intermediate piezoelectric actuator 32. The second pair comprises a third intermediate piezoelectric actuator 33 and a fourth intermediate piezoelectric actuator 34. The intermediate piezoelectric actuators 31-34 of each pair are identical. In the example shown, all the intermediate piezoelectric actuators 31-34 are of substantially the same length, which length is less than that of the piezoelectric actuators 4, 5, 15.

[0137]

[0135] The first intermediate piezoelectric actuator 31 has a first end 36 mechanically assembled to the first end 7 of the second piezoelectric actuator 5, while the second intermediate piezoelectric actuator 32 has a first end 37 mechanically assembled to the first end 6 of the first piezoelectric actuator 4.

[0138]

[0136] The first intermediate piezoelectric actuator 31 has a second end 38, opposite the first end 36, mechanically assembled to a second end 39 of the second intermediate piezoelectric actuator 32, opposite the first end 37.

[0139]

[0137] The third intermediate piezoelectric actuator 33 has a first end 40 mechanically assembled to the first end 16 of the third piezoelectric actuator 15, while the fourth intermediate piezoelectric actuator 34 has a first end 41 mechanically assembled to the first end 6 of the first piezoelectric actuator 4.

[0140]

[0138] The third intermediate piezoelectric actuator 33 has a second end 42, opposite the first end 40, mechanically assembled to a second end 43 of the fourth intermediate piezoelectric actuator 34, opposite the first end 41.

[0141]

[0139] The intermediate piezoelectric actuators 31-34 are here mechanically assembled to each other or to the piezoelectric actuators by means of connecting means 8, here of which there are six.

[0142]

[0140] In addition, the longitudinal axes of each of the piezoelectric actuators 4, 5, 15 and intermediate piezoelectric actuators 31-34 are at a distance from each other of less than four times, preferably less than ten times, the length of the piezoelectric actuators 4, 5, 15 or the intermediate piezoelectric actuators 31-34.

[0141] The intermediate piezoelectric actuators 31-34 deform like the piezoelectric actuators 4, 5, 15. The first ends 6, 7, 16 of the piezoelectric actuators 4, 5, 15 and the first ends 36, 37, 40, 41 of the intermediate piezoelectric actuators 31-34 are aligned in a direction perpendicular to the longitudinal axes of the piezoelectric actuators 4, 5, 15.

[0143]

[0142] In this way, within each pair of intermediate piezoelectric actuators, the deformation of one compensates for the deformation of the other when they deform in the same way, for example when the deformation is caused by a drift.

[0144]

[0143] The intermediate piezoelectric actuators 31-34 are here mechanically assembled to each other or to the piezoelectric actuators by means of connecting means 8, here of which there are six.

[0145]

[0144] Figure 9 is a partial representation of the switch 201 according to the third embodiment, in which the third piezoelectric actuator and the third and fourth intermediate piezoelectric actuators have been omitted for clarity. The description below, however, remains applicable to the latter.

[0146]

[0145] The piezoelectric actuators 4, 5 and the intermediate piezoelectric actuators 31, 32 are shown here in their rest position, and the switch 201 is shown here in an open configuration as its default configuration. The distances denoted here as d4 and d5 correspond to the distances d4 and d5 described with reference to the first embodiment. Note that the distance between the first end of the third piezoelectric actuator, not shown here, and the second contact is equal to the distance d5.

[0147]

[0146] The distance between the first end 36 and the second end 38 of the first intermediate piezoelectric actuator 31, that is to say its length, denoted here dsi, is equal to the distance between the first end 37 and the second end 39 of the second intermediate piezoelectric actuator 32, denoted here ds2- Thus, when the piezoelectric actuators 4, 5 and the intermediate piezoelectric actuators 31, 32 are at rest, the switch 201 is here configured to satisfy the following inequality: d5- d4+ d32 - dsi = e > 0.

[0148]

[0147] To switch the 201 from its open to its closed position, the first actuator 4 and the intermediate actuators 31 and 33 must be placed in their extended state and / or the second and third actuators 5, 15 and the intermediate actuators 32 and 34 must be placed in their retracted state. To achieve this, the electric field applied to the first actuator 4 and the intermediate actuators 31 and 33 and / or to the second and third actuators 5, 15 and the intermediate actuators 32 and 34 is modified.

[0149]

[0148] By configuring the piezoelectric actuators 4, 5 so that the sum of the distances d4 or d4 and dsi or daiA is greater than the sum of the distances d5 or d5R and d32 or d32A, a contact force is generated at the interface between the first contact 2 and the second contact 3, which ensures a more stable electrical connection, reduces electrical resistance and allows the passage of relatively high currents.

[0150]

[0149] The same principle applies to switching switch 201 from its closed configuration to its open configuration.

[0151]

[0150] Thus, when the intermediate piezoelectric actuators 31-34 are in the same state, the switch 201 behaves like the switch 101 according to the second embodiment. On the other hand, when the intermediate piezoelectric actuators 31-34 of the same pair are in different states, the displacement amplitude of the first piezoelectric actuator 4 relative to the second and third piezoelectric actuators 5, 15 is increased, without increasing the length of the piezoelectric actuators 4, 5, 15.

[0152]

[0151] In an unrepresented variant, the switch further comprises guide rings, as described with reference to the switch according to the second embodiment.

[0153]

[0152] Figures 10 to 14 show a switch according to a fourth embodiment. This switch has three actuators, like that of the second embodiment, but differs structurally in that the piezoelectric actuators are arranged differently and the third piezoelectric actuator has a different length than the other two. For simplicity of description, the same reference numerals have therefore been used, except for the switch, for which a similar reference numeral, but with the number 200 added, has been used.

[0154]

[0153] In this switch 301, the longitudinal axes X4, X5 of the first piezoelectric actuator 4 and the second piezoelectric actuator 5 are aligned. The third piezoelectric actuator 15 is juxtaposed and extends substantially parallel to the first and second piezoelectric actuators 4, 5. The third piezoelectric actuator 15 defines a general plane of extension P with the latter. Its first end 16 is mechanically assembled to the first end 6 of the first piezoelectric actuator 4, and its second end 17 is mechanically assembled to the first end 7 of the second piezoelectric actuator 5. The piezoelectric actuators 4, 5, 15 are mechanically joined together by means of connecting means 8, here of which there are two.

[0155]

[0154] The first end 6 of the first piezoelectric actuator 4 is aligned with the first end 16 of the third piezoelectric actuator 15 in a direction perpendicular to the longitudinal axis X4. The first end 7 of the second piezoelectric actuator 5 is aligned with the second end 17 of the third piezoelectric actuator 15 in a direction perpendicular to the longitudinal axis X5.

[0156]

[0155] The second end 9 of the first piezoelectric actuator 4 carries the first contact 2 while the second end 10 of the second piezoelectric actuator 5 here carries the second contact 3.

[0157]

[0156] The switch 301 has a plane of symmetry P sym2 which passes between the first and second piezoelectric actuators 4, 5 and at the center of the third piezoelectric actuator 15 and which is perpendicular to both the general extension plane P and the longitudinal axes X4, X5, Xi5 of the piezoelectric actuators 4, 5, 15.

[0158]

[0157] In the example shown, the base 13 is in contact with a central area of ​​the third piezoelectric actuator 15. It is, for example, arranged symmetrically with respect to the plane of symmetry P sym 2.

[0159]

[0158] It should be noted that Figures 11 to 14 illustrate the switch 301 from a top view. However, they could also illustrate the switch 301 from a side view. In particular, the switch could be rotated 90° around the longitudinal axis of the third piezoelectric actuator so that the general plane of extension is perpendicular to the surface.

[0160]

[0159] In Figures 10 and 11, the piezoelectric actuators 4, 5, 15 are shown at rest, and the switch 301 is shown here in an open configuration as its default configuration. In this state, the first and second piezoelectric actuators 4, 5 have substantially identical lengths.

[0161]

[0160] The length of the third piezoelectric actuator 15 is substantially equal to the sum of the lengths of the first and second piezoelectric actuators 4, 5. All the piezoelectric actuators 4, 5, 15 have a substantially identical cross-section. It will be understood that, since the cumulative length of the first and second piezoelectric actuators 4, 5 is substantially equal to the length of the third actuator 15, it is not necessary for the first and second actuators 4, 5 to be of the same length.

[0162]

[0161] With reference to Figure 11, the sum of the distance between the first end 6 of the first piezoelectric actuator 4 and the first contact 2, denoted here as d4, and the distance between the first end 7 of the second piezoelectric actuator 5 and the second contact 3, denoted here as d5, is less than the distance between the first end 16 and the second end 17 of the third piezoelectric actuator 15, denoted here as di5, i.e., its length. The difference between the sum of the distances d4 and d5 and the distance di5 corresponds to the air gap e. Thus, when the piezoelectric actuators 4, 5, and 15 are at rest, the switch 301 is configured to satisfy the following inequality: di5 - (d4 + d5) = e > 0.

[0163]

[0162] In Figure 12, the piezoelectric actuators 4, 5, and 15 are all three in their retracted state, under the effect of a first predetermined electric field. The distance between the first end 6 of the first piezoelectric actuator 4 and the first contact 2, denoted d 4R , is here less than the distance d4. Similarly, the distance between the first end 7 of the second piezoelectric actuator 5 and the second contact 3, denoted d 5R , is here less than the distance d5, and the length of the third piezoelectric actuator, denoted here di 5R , is less than the distance di5.

[0164]

[0163] In Figure 13, the piezoelectric actuators 4, 5, and 15 are all in their extended state, under the effect of a second predetermined electric field. The distance between the first end 6 of the first piezoelectric actuator 4 and the first contact 2, denoted d4, is greater than the distance d4. Similarly, the distance between the first end 7 of the second piezoelectric actuator 5 and the second contact 3, denoted d5A, is greater than the distance d5, and the length of the third piezoelectric actuator, denoted di5A, is greater than the distance di5.

[0165]

[0164] Since the third piezoelectric actuator 15 is made of the same material and has a length substantially equal to the sum of the lengths of the first and second piezoelectric actuators 4, 5, its deformation is substantially equal to the sum of the deformations of the first and second piezoelectric actuators 4, 5 when they are subjected to drifts.

[0166]

[0165] Denoting L4 as the length of the first piezoelectric actuator 4 in its rest state, L5 as the length of the second piezoelectric actuator 5 in its rest state, L15 as the length of the third piezoelectric actuator 15 in its rest state, and defining a value a that corresponds to the rate of change in the length of the piezoelectric actuators under the effect of temperature, humidity, or aging, the modified lengths can be written as follows: L4m = aL4, L5m = aL5 and L15m = aL15. The modified value of the air gap can also be written as follows: em = e + aL15 - aL5 - aL4 = e + a(L15 - L5 - L4). Thus, since the length of the third piezoelectric actuator 15 is equal to the sum of the lengths of the first and second piezoelectric actuators 4, 5, the contacts 2, 3 maintain an unchanged relative position, which eliminates the risk of accidental closing or opening in case of drift.

[0167]

[0166] To switch the 301 from the open to the closed position, at least one of the piezoelectric actuators 4, 5, 15 must be placed in a state different from the others. To do this, the electric field applied to the first actuator 4 and / or the second actuator 5 and / or the third actuator 15 is changed.

[0168]

[0167] By configuring the piezoelectric actuators so that the sum of the distances d4 or d4A and d5 or d5A is greater than the distance di5 or di5A, a contact force is generated at the interface between the first contact 2 and the second contact 3, which ensures a more stable electrical connection, reduces electrical resistance and allows the passage of relatively high currents.

[0169]

[0168] The same principle applies to switching switch 301 from its closed configuration to its open configuration.

[0170]

[0169] In addition to the advantages associated with the switch 1 according to the first embodiment, this switch 301 exhibits a symmetry that allows a substantially fixed center of gravity to be maintained during actuation, thus reducing vibrations. This is possible because the first and second piezoelectric actuators 4, 5 move in opposite directions, and the third piezoelectric actuator 15 deforms substantially symmetrically about its center. More precisely, the central area of ​​the third piezoelectric actuator 15 exhibits almost no mechanical displacement, since the forces are applied in opposite directions on each side of this area.

[0171]

[0170] Furthermore, the first and second piezoelectric actuators 4, 5 are arranged relative to the third piezoelectric actuator 15 such that the center of gravity of these first and second piezoelectric actuators 4, 5 is at a distance from the center of gravity of the third piezoelectric actuator 15 less than four times, preferably less than ten times, the length of the first piezoelectric actuator 4 or the second piezoelectric actuator 5. In other words, the longitudinal axes X4, X5 of the first and second piezoelectric actuators 4, 5 are at a distance from the longitudinal axis Xi5 of the third piezoelectric actuator 15 less than four times, preferably less than ten times, the length of the first piezoelectric actuator 4.

[0172]

[0171] In an alternative embodiment not shown, the third piezoelectric actuator is formed by two piezoelectric actuators arranged end to end. These two piezoelectric actuators are then substantially identical to the first and second piezoelectric actuators.

[0173]

[0172] Figure 15 shows a switch according to a fifth embodiment. This switch differs structurally from that of the fourth embodiment in that the second actuation assembly includes an additional piezoelectric actuator, hereinafter referred to as the fourth piezoelectric actuator. For the sake of simplicity, the same reference numerals have therefore been used, except for the switch, for which a similar reference numeral, but with the addition of the number 100, has been used.

[0174]

[0173] In this switch 401, the fourth piezoelectric actuator 40 is identical to the third piezoelectric actuator 15. It has a first end 41 mechanically assembled to the first end 6 of the first piezoelectric actuator 4 and a second end 42, opposite to the first end 41, mechanically assembled to the first end 7 of the second piezoelectric actuator 5.

[0175]

[0174] The piezoelectric actuators 4, 5, 15, 40 are mechanically assembled together by means of connecting means 8, here of which there are four.

[0176]

[0175] The first and second piezoelectric actuators 4, 5 extend between the third and fourth piezoelectric actuators 15, 40. The switch 301 has a first plane of symmetry P symi which divides the first and second piezoelectric actuators 4, 5 along their length and which is perpendicular to the general extension plane P as well as a second plane of symmetry P sym 2 which passes between the first and second piezoelectric actuators 4, 5 and at the center of the third and fourth piezoelectric actuators 15, 40 and which is perpendicular to both the general extension plane P and the longitudinal axes of the piezoelectric actuators 4, 5, 15, 40.

[0177]

[0176] In the example shown, the switch 401 further includes an additional (not visible) base configured, with the base 13, to keep the piezoelectric actuators 4, 5, 15, 40 at a distance from the surface S, partially shown in Figure 15, in order to limit friction on the surface S during the deformation of the piezoelectric actuators 4, 5, 15. The additional base is in contact with a central area of ​​the fourth piezoelectric actuator 40. For example, it is arranged symmetrically to the base 13 with respect to the first plane of symmetry P sym i.

[0177] In an alternative embodiment not shown, the switch further comprises guide rings as described with reference to the switch according to the second embodiment. The guide rings can, for example, replace the base or bases.

[0178]

[0178] Since the third piezoelectric actuator 15 and the fourth piezoelectric actuator 40 are identical, they deform in the same way, for example in response to drift. Thus, the switch 401 reacts in the same way to drift as the switch 301 according to the fourth embodiment.

[0179]

[0179] To switch the 401 from the open to the closed position, at least one of the actuators 4 and 5 must be placed in their extended state and / or the actuators 15 and 40 in their retracted state. This is achieved by changing the electric field applied to at least one of the actuators 4 and 5 and / or to the actuators 15 and 40.

[0180]

[0180] In other words, it is possible to apply the same process as that described with reference to switch 301 according to the fourth embodiment, but by actuating the third and fourth piezoelectric actuators 15, 40 in the same way.

[0181]

[0181] The first plane of symmetry P symi corresponds globally to the plane of symmetry of the second embodiment, while the second plane of symmetry P sym 2 corresponds broadly to the plane of symmetry of the fourth embodiment. Thus, switch 401 exhibits both the advantages related to the symmetry of the second embodiment and the advantages related to the symmetry of the fourth embodiment.

[0182]

[0182] Furthermore, the first and second piezoelectric actuators 4, 5 are arranged relative to the third piezoelectric actuator 15 such that the center of gravity of these first and second piezoelectric actuators 4, 5 is at a distance from the center of gravity of the third piezoelectric actuator 15 that is less than four times, preferably less than ten times, the length of the first piezoelectric actuator 4 or the second piezoelectric actuator 5. In other words, the longitudinal axes X4, X5 of the first and second piezoelectric actuators 4, 5 are at a distance from the longitudinal axis Xi5 of the third piezoelectric actuator 15 that is less than four times, preferably less than ten times, the length of the first piezoelectric actuator 4. The same applies to the distance between the longitudinal axes X4, X5 of the first and second piezoelectric actuators and the axis X4o of the fourth actuator piezoelectric 40.

[0183]

[0183] Figure 16 shows a first variant of the switch 401 according to the fifth embodiment. This switch is functionally similar to that of the fourth embodiment, but differs structurally in that it has two additional contacts, hereinafter referred to as the third and fourth contacts respectively, and two additional piezoelectric actuators, hereinafter referred to as the fifth and sixth piezoelectric actuators respectively, each carrying one of the additional contacts. For the sake of simplicity, the same reference numerals have therefore been used.

[0184] In this switch 401, the third and fourth contacts 43, 44 are identical to the first and second contacts 2, 3. The fifth and sixth piezoelectric actuators 45, 46 are identical to the first and second piezoelectric actuators 4, 5.

[0184]

[0185] The fifth piezoelectric actuator 45 has a first end 47 mechanically assembled to the first end 6 of the first piezoelectric actuator 4. The third contact 43 is fixed to a second end 48, opposite to the first end 47, of the fifth piezoelectric actuator 45.

[0185]

[0186] The sixth piezoelectric actuator 46 has a first end 49 mechanically assembled to the first end 7 of the second piezoelectric actuator 5. The fourth contact 44 is fixed to a second end 50, opposite to the first end 49, of the sixth piezoelectric actuator 46.

[0186]

[0187] The piezoelectric actuators 4, 5, 15, 40, 45, 46 are here mechanically assembled together by means of connecting means 8, here of which there are six.

[0187]

[0188] The fifth and sixth piezoelectric actuators 45, 46 extend between the first and second piezoelectric actuators 4, 5 and the fourth piezoelectric actuator 40.

[0188]

[0189] Switch 401 has a first plane of symmetry P sy mi which passes between the first and second piezoelectric actuators 4, 5 and the fifth and sixth piezoelectric actuators 45, 46 and which is perpendicular to the general extension plane P and parallel to the longitudinal axis of the piezoelectric actuators 4, 5, 15, 40, 45, 46 as well as a second plane of symmetry P sym 2 which passes between the first and second piezoelectric actuators 4, 5, between the fifth and sixth piezoelectric actuators 45, 46 and at the center of the third and fourth piezoelectric actuators 15, 40 and which is perpendicular to both the general extension plane P and the longitudinal axes of the piezoelectric actuators 4, 5, 15, 40, 45, 46.

[0189]

[0190] In an alternative variant not shown, the switch further includes guide rings as described with reference to the switch according to the second embodiment. The guide rings can, for example, replace the base or bases.

[0190]

[0191] Since the fifth piezoelectric actuator 45 and the sixth piezoelectric actuator 46 are identical, they deform identically in response to drift. Thus, this switch 401 reacts in the same way to variations in temperature and / or humidity and / or aging conditions as the switch 401 according to the fifth embodiment.

[0191]

[0192] To switch the 401 switch from the open configuration to the closed configuration, the same process as described in reference to the 401 switch according to the fifth embodiment should be applied, but actuating the first and second piezoelectric actuators 4, 5 and the fifth and sixth piezoelectric actuators 45, 46 in the same way.

[0192]

[0193] When a single piezoelectric actuator has multiple contacts, some contacts may experience a greater force than others upon contact, leading to a risk of uneven force distribution. To mitigate this risk, adding one or more additional piezoelectric actuators, each with a separate contact, helps to homogenize the forces across the different electrical contacts. In other words, since each contact has its own actuator, the applied forces are distributed more evenly and in a more controlled manner, thus reducing variations in force between the contacts.

[0193]

[0194] Figure 17 shows a second variant of the switch 401 according to the fifth embodiment. This switch is functionally similar to that of the fourth embodiment, but differs structurally in that the piezoelectric actuators are formed from the same plate of piezoelectric material 71.

[0194]

[0195] In the illustrated example, the piezoelectric material plate 71 is rectangular in shape and has a through groove 72 in the shape of an H so as to form two short bars aligned longitudinally and two long bars extending on either side of the short bars.

[0195]

[0196] The electrodes are arranged along part of the length of the bars. The parts covered by the electrodes form the piezoelectric actuators, and are arranged as in the switch according to the fourth embodiment.

[0196]

[0197] Thus, the switch comprises a first piezoelectric actuator 4 and a second piezoelectric actuator 5 of the same length, as well as a third piezoelectric actuator 15 and a fourth piezoelectric actuator 40 of the same length. As previously stated, it is not necessary for the first and second actuators 4 and 5 to be of the same length since the combined length of the first and second piezoelectric actuators 4 and 5 is substantially equal to the length of the third actuator 15.

[0197]

[0198] The parts of the bars not covered by the electrodes are arranged as the means of connection.

[0198]

[0199] Figures 18 to 22 show a switch according to a sixth embodiment. This switch differs structurally from that of the first embodiment in that each actuation assembly additionally includes an amplifying structure mounted on the piezoelectric actuator. For simplicity, the same numerical references have therefore been used, except for the switch, for which a similar reference number, but with the addition of the number 500, has been used.

[0199]

[0200] In this switch 501, the first actuation assembly includes a first amplifier structure 55 mounted on the first piezoelectric actuator 4. The second actuation assembly includes a second amplifier structure 56 mounted on the second piezoelectric actuator 5.

[0200]

[0201] The first and second amplifying structures 55, 56 are made of a different material than the piezoelectric actuators 4, 5. For example, each amplifying structure can be made of metal, such as stainless steel, copper, zinc or other stainless metal alloys, or of a hard plastic such as PEEK.

[0202] The first amplifying structure 55 comprises two first levers 57 and a first connecting element 58. Each of the first levers 57 has a first end 59 mechanically pivotally assembled to a respective end 6, 9 of the first piezoelectric actuator 4 and a second end 61, opposite the first end 59, mechanically pivotally assembled to the first connecting element 58. In the illustrated example, the first levers 57 are fixed to a first face of the first piezoelectric actuator 4.

[0201]

[0203] The second amplifying structure 56 comprises two second levers 63 and a second connecting element 64. Each of the second levers 63 has a first end 65 mechanically pivotally assembled to a respective end 7, 10 of the second piezoelectric actuator 5 and a second end 66, opposite the first end 65, mechanically pivotally assembled to the second connecting element 64. In the illustrated example, the second levers 63 are fixed to a first face of the second piezoelectric actuator 5.

[0202]

[0204] The pivot link between each lever 57, 63 and each piezoelectric actuator 4, 5 and / or between each lever 57, 63 and each connecting element 58, 64 can be formed by a joint or by elastic deformation of material, for example locally favored by thinning, if the levers 57, 63 and the connecting element 58, 64 are formed as a single piece.

[0203]

[0205] The first contact 2 is fixed to the first connecting element 58 and the second contact 3 is fixed to the second connecting element 64. The second connecting element 58 is configured to hold the second contact 3 opposite the first contact 2, so that they are aligned in a direction perpendicular to the direction of deformation D of the piezoelectric actuators 4, 5. The second connecting element 58 thus acts as a support arm.

[0204]

[0206] In the example shown, the base 13 is in contact with a central area of ​​the first piezoelectric actuator 4 and a central area of ​​the second piezoelectric actuator 5. In other words, a central area of ​​the first piezoelectric actuator 4 as well as a central area of ​​the second piezoelectric actuator 5 rest on the base 13, while the rest of the first piezoelectric actuator 4 and the rest of the second piezoelectric actuator 5 are suspended in equilibrium above the surface S.

[0205]

[0207] In Figures 18 and 19, the piezoelectric actuators 4 and 5 are shown at rest, and switch 501 is shown in its open configuration as the default. In this state, the piezoelectric actuators 4 and 5 have substantially identical dimensions, and switch 501 is in its open configuration. In particular, the piezoelectric actuators 4 and 5 have substantially identical cross-sectional areas and lengths.

[0206]

[0208] Furthermore, the first and second connecting elements 58, 64 are set apart respectively from the first and second piezoelectric actuators 4, 5. The first levers 57, 63 form an angle α with the connecting element, which is here greater than 90° and less than 180°, as illustrated in Figure 18.

[0209] In the illustrated example, the first face of the first piezoelectric actuator 4 and the first face of the second piezoelectric actuator 5 are substantially aligned, that is to say, they are substantially in the same plane, here parallel to the general extension plane P of the switch 501.

[0207]

[0210] Referring to Figure 19, the distance between the first face of the first piezoelectric actuator 4 and the first contact 2, denoted here as dio4, is less than the distance between the first face of the second piezoelectric actuator 5 and the second contact 3, denoted here as dl05. The difference between the distances dio4 and dios corresponds to the air gap e. Thus, the switch 501 is configured here to satisfy the following inequality: dios - dio4 = e > 0.

[0208]

[0211] Note that figures 19 to 21, the second piezoelectric actuator 5 and the second amplifier structure 65 are not visible because they are behind the first piezoelectric actuator 4 and the first amplifier structure 55.

[0209]

[0212] In Figure 20, the piezoelectric actuators 4 and 5 are in their retracted state, under the effect of a first predetermined electric field. The distance between the first face of the first piezoelectric actuator 4 and the first contact 2, denoted dio4R, is here less than the distance dio4-. Similarly, the distance between the first face of the second piezoelectric actuator 5 and the second contact 3, denoted diosR, is here less than the distance dios-

[0210]

[0213] In Figure 21, the piezoelectric actuators 4 and 5 are in their extended state, under the influence of a second predetermined electric field. The distance between the first face of the first piezoelectric actuator 4 and the first contact 2, denoted dio4A, is greater than the distance dio4-. Similarly, the distance between the first face of the second piezoelectric actuator 5 and the second contact 3, denoted diosA, is greater than the distance dios-.

[0211]

[0214] Denoting L4 as the length of the first piezoelectric actuator 4 in its rest state, and L5 as the length of the second piezoelectric actuator 5 in its rest state, and defining a value a corresponding to the rate of change in the length of the piezoelectric actuators due to temperature, humidity, or aging, and G as the mechanical amplification factor related to the amplifying structures 55, 56, we can write the modified lengths as follows: L4m = aL4 and L5m = aL5. We can also write the modified value of the air gap as follows: em = e + aGL5 - aGL4 = e + aG (L5 - L4). Thus, since the piezoelectric actuators 4, 5 are approximately the same length, the contacts 2, 3 maintain an unchanged relative position, which eliminates the risk of accidental opening or closing in case of drift.

[0212]

[0215] To switch the 501 switch from the open configuration to the closed configuration, the first piezoelectric actuator 4 should be placed in its retracted state and / or the second piezoelectric actuator 5 in its extended state, as for the switch in the first embodiment.

[0213]

[0216] By configuring the piezoelectric actuators 4, 5 so that the distance dio4 or dio4R is greater than the distance dios or diosA, a contact force is generated at the interface between the first contact 2 and the second contact 3, which ensures a more stable electrical connection, reduces electrical resistance and allows the passage of relatively high currents.

[0214]

[0217] The same principle applies to switching switch 501 from its closed configuration to its open configuration.

[0215]

[0218] In an alternative (not shown) variant, each amplifier structure further comprises two additional levers mechanically pivotally attached to the piezoelectric actuator, and an additional connecting element mechanically pivotally attached to these additional levers. The levers are, for example, attached to a second face of the piezoelectric actuator opposite the first face. Alternatively, or in addition, the additional levers can be mechanically attached to the existing levers.

[0216]

[0219] The use of amplifying structures makes it possible to reduce the length of the actuator while maintaining the same amplitude of movement.

[0217]

[0220] Figure 23 shows a first example of contact arrangement on piezoelectric actuators. In this example, the switch 1 has four distinct contacts, namely two first contacts 70 carried by the first piezoelectric actuator 4 and two second contacts 72 carried by the second piezoelectric actuator 5.

[0218]

[0221] The first contacts 70 and the second contacts 72 are each intended to be electrically connected to an electrical circuit or part of an electrical circuit (not shown). In particular, the first contacts 70 are intended to be connected to the same electrical circuit or part of an electrical circuit, while the second contacts 72 are intended to be connected to a different electrical circuit or part of an electrical circuit.

[0219]

[0222] In the example shown, each contact 70, 72 is electrically connected to an electrical circuit or part of an electrical circuit (not shown) by a flexible conducting wire 75.

[0220]

[0223] Each contact 70, 72 comprises a mounting portion 73 fixed to one of the main faces of the piezoelectric actuator 4, 5, and a connecting portion 74 extending from the mounting portion 73 and projecting from the end face of the piezoelectric actuator 4, 5. The mounting portion 73 and the connecting portion 74 of each contact 70, 72 extend generally parallel to the longitudinal axis of the piezoelectric actuator 4, 5 by which it is supported. The mounting portion 73 and the connecting portion 74 are formed as a single unit.

[0221]

[0224] In an unrepresented variant, only two contacts carried by the same piezoelectric actuator have their connection part protruding from the end face of said piezoelectric actuator, while the contacts carried by the other piezoelectric actuator have their connection part flush with or recessed from the end face of that other piezoelectric actuator.

[0222]

[0225] A layer of insulating material 76 is interposed here between the connection part 73 of each contact 70, 72 and each piezoelectric actuator 4, 5 on which it is fixed.

[0226] Figure 24 shows a second example of contact arrangement on piezoelectric actuators. In this example, the contacts differ structurally from those in the first example in that the connecting part has a different shape. For simplicity, the same numerical references have therefore been used.

[0223]

[0227] The connection part 74 of each contact here has an L-shaped form, with an end arm 78 which extends opposite and away from the end face of the piezoelectric actuator 4, 5 and an intermediate arm 79 which mechanically connects the end arm 78 to the fixing part 73. In particular, the intermediate arm 79 is connected to one end of the end arm 78 while an opposite end of the end arm 78 is free and is opposite and away from the end face.

[0224]

[0228] The connection part 74 further includes a contact point 80 disposed on the side of the free end of the end arm 78 and extending in projection opposite the end face of the piezoelectric actuator 4, 5. The contact points 80 of the first and second contacts 70, 72 are opposite and are configured to come into contact with each other when the switch 1 is in its closed configuration.

[0225]

[0229] When a force is applied to the contact point 80, the free end of the end arm 78 is moved towards the end face of the piezoelectric actuator 4, 5 and the connecting part 74 is elastically deformed at the junction between the intermediate arm 79 and the end arm 78. Such an arrangement thus provides a certain mechanical flexibility to the contact points 80, which allows to absorb possible position errors.

[0226]

[0230] Figure 25 shows a third example of contact arrangement on piezoelectric actuators. In this example, the switch has one contact on the first piezoelectric actuator and two contacts on the second piezoelectric actuator. For simplicity, the same numerical references have been used.

[0227]

[0231] Here, the first contact 70 is not connected to an electrical circuit or part of an electrical circuit. Each second contact 72 is intended to be electrically connected to an electrical circuit or part of an electrical circuit (not shown), here via flexible conductor wires 75. The first contact 70 is configured to electrically connect the second contacts 72 together when the switch 1 is in its closed position.

[0228]

[0232] In the example shown, the second contacts 72 are spaced apart and arranged on the same face of the second piezoelectric actuator 5.

[0229]

[0233] In an unrepresented variant, the switch has another first contact which is arranged on an opposite face of the first piezoelectric actuator and two other second contacts which are arranged on an opposite face of the second piezoelectric actuator, as in the examples illustrated in Figures 22 and 23.

[0230]

[0234] The contacts can be used in switches of all the embodiments described above.

Claims

1. Claims 1. An electrical switch adapted to have a closed configuration and an open configuration, comprising: a first contact (2), a second contact (3), a first actuation assembly carrying the first contact (2) and comprising a first piezoelectric actuator (4), a second actuation assembly carrying the second contact (3) and comprising a second piezoelectric actuator (5), each of the first piezoelectric actuator (4) and the second piezoelectric actuator (5) deforming, under the effect of a change in electric field and / or a variation of an operational parameter specific to the actuator or its surrounding environment, such as fatigue, ambient temperature or ambient humidity, along a deformation direction (D) substantially collinear with a longitudinal axis (Xi, X2) of the piezoelectric actuator (4, 5), between a retracted state and an extended state,the first and second actuation sets extending in the same general plane of extension (P) and being configured such that, when the first piezoelectric actuator (4) and the second piezoelectric actuator (5) are subjected to the same variation of an operational parameter, the configuration in which the switch is located is maintained, while the deformation under the effect of a change in the electric field of one and / or the other of the piezoelectric actuators (4, 5) causes the switch to transition from one configuration to the other, where the closed configuration corresponds to the contact between the first and second contacts (2, 3), and where the open configuration corresponds to the absence of contact between the first and second contacts (2, 3).

2. Switch according to claim 1, wherein the first piezoelectric actuator (4) and the second piezoelectric actuator (5) are made of one or the same materials.

3. Switch according to claim 1 or 2, wherein the first piezoelectric actuator (4) and the second piezoelectric actuator (5) extend parallel to each other.

4. Switch according to any one of claims 1 to 3, wherein the second actuation assembly comprises a third piezoelectric actuator (15) having a first end (16) mechanically assembled to the first piezoelectric actuator (4) and a second end (17), opposite to the first end (16), mechanically assembled to the second piezoelectric actuator (5).

5. A switch according to claim 4, wherein the first piezoelectric actuator (4) has a first end (6) mechanically assembled to the first end (16) of the third piezoelectric actuator (15) and a second end (9), opposite the first end (6), bearing the first contact (2), the second piezoelectric actuator (5) having one end (7) mechanically assembled to the first end (6) of the first piezoelectric actuator (4).

6. Switch according to any one of claims 4 or 5, wherein the switch (101, 201, 301, 401) has a first plane of symmetry (PSY I) which divides the first piezoelectric actuator (4) along its length and which is perpendicular to the general extension plane (P) and / or a second plane of symmetry (PSYM?) which passes between the first and second piezoelectric actuators (4, 5) and through the center of the third piezoelectric actuator (15) and which is perpendicular to both the general extension plane (P) and the longitudinal axes (X4, X5, Xi5) of the piezoelectric actuators (4, 5, 15).

7. A switch according to any one of claims 4 to 6, wherein the second actuation assembly further comprises a first intermediate piezoelectric actuator (31) and a second intermediate piezoelectric actuator (32), the first and second intermediate piezoelectric actuators (31, 32) being disposed between the first piezoelectric actuator (4) and the second piezoelectric actuator (5), the first and second intermediate piezoelectric actuators (31, 32) being made of the same material and having substantially identical dimensions, the first intermediate piezoelectric actuator (31) having a first end (36) mechanically assembled to the first end (7) of the second actuator (5) and a second end (38), opposite the first end (36),the second intermediate piezoelectric actuator (32) having a first end (37) mechanically assembled to the first end (6) of the first piezoelectric actuator (4) and a second end (39), opposite the first end (37), mechanically assembled to the second end (38) of the first intermediate piezoelectric actuator (31).

8. Switch according to claim 7, wherein the second actuation assembly further comprises a third intermediate piezoelectric actuator (33) and a fourth intermediate piezoelectric actuator (34), the third and fourth intermediate piezoelectric actuators (33, 34) being arranged substantially symmetrically to the first and second intermediate piezoelectric actuators (31, 32) with respect to a plane of symmetry (PSYMI) which divides the first piezoelectric actuator (4) lengthwise and which is perpendicular to the general extension plane (P).

9. Switch according to any one of claims 1 to 8, wherein the distance separating the first contact (2) and the second contact (3) when the switch is in the open configuration is between 0.00002 and 0.005 times the length of one of the first and second piezoelectric actuators.

10. Switch according to any one of claims 4 to 9, wherein the second actuation assembly comprises a support arm (12) carrying the second contact (3), the support arm (12) being fixed to the second end (10) of the second piezoelectric actuator (5) and to the second end (17) of the third piezoelectric actuator (15).

11. Switch according to claim 10, wherein the first piezoelectric actuator (4) is arranged between the second piezoelectric actuator (5) and the third piezoelectric actuator (15).

12. Switch according to any one of claims 10 and 11, wherein the first piezoelectric actuator (4), the second piezoelectric actuator (5) and the third piezoelectric actuator (15) have substantially the same length.

13. Switch according to any one of claims 4 to 9, wherein the second piezoelectric actuator (5) has a first end (7) mechanically assembled to the second end (17) of the third piezoelectric actuator (15) and a second end (10), opposite to the first end (7), carrying the second contact (3).

14. Switch according to claim 13, wherein the third piezoelectric actuator (15) has a length substantially equal to the sum of the length of the first piezoelectric actuator (4) and the length of the second piezoelectric actuator (5).

15. Switch according to any one of claims 1 to 14, wherein the first contact (2) and the second contact (3) are moved in a direction parallel to the direction of deformation (D) when the piezoelectric actuators (4, 5, 15, 40, 45, 46) are deformed between the retracted state and the elongated state.

16. Switch according to any one of claims 1 to 3, wherein the contacts are moved in a direction perpendicular to the direction of deformation (D) when the piezoelectric actuators (4, 5) are deformed between the retracted state and the elongated state.

17. Switch according to claim 16, wherein the first actuation assembly comprises a first amplifying structure (55) and the second actuation assembly comprises a second amplifying structure (56), the first amplifying structure (55) being mechanically assembled on the first piezoelectric actuator (4) and carrying the first contact (2), the second amplifying structure (56) being mechanically assembled on the second piezoelectric actuator (5) and carrying the second contact (3).

18. Switch according to any one of claims 1 to 15, wherein the longitudinal axes (X4, X5) of the first and second piezoelectric actuators (4, 5) are at a distance from each other of less than four times, preferably less than ten times, the length of the first piezoelectric actuator (4) or the second piezoelectric actuator (5).

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