Pump actuated by piezoelectric transducers

Abstract

Pump (1) intended to pump a fluid between an inlet and an outlet, including:a first annular piezoelectric transducer (11) extending around a central axis (A) and including a first electrode (12);a first resonator (10) connected to the first piezoelectric transducer and extending around the central axis, the first resonator becoming thinner toward the central axis and being deformed by the effect of polarisation of the first piezoelectric transducer;a control unit (30) configured to polarise the first electrode at a polarisation voltage;the first resonator defines a cavity (2) extending around the central axis and configured to receive the fluid;the pump includes at least one channel (4) discharging into the cavity;deformation of the resonator is produced because of the effect of the polarisation of the first piezoelectric transducer, locally and temporarily reducing the thickness of the cavity.

1 . A pump configured to pump a fluid between an inlet and an outlet, including:
 a first annular piezoelectric transducer extending around a central axis and including a first electrode;   a first resonator connected to the first piezoelectric transducer and extending around the central axis, the first resonator being formed of a deformable solid material becoming thinner toward the central axis, the first resonator being configured to be deformed when the first piezoelectric transducer is polarised;   a control unit configured to polarise the first electrode at a polarisation voltage modulated with a modulation frequency greater than 20 kHz;   
       wherein:
 the first resonator defines a cavity extending around the central axis and configured to receive the fluid, the cavity thickness extending along the central axis; 
 the pump includes a first sleeve connected to the first resonator opening into the centre of the cavity and forming the inlet of the pump; 
 the pump includes at least one channel discharging from the cavity, the channel extending along the first resonator about an axis perpendicular to the central axis, the channel forming the outlet of the pump; 
 so that under the effect of the polarisation of the first piezoelectric transducer deformation of the resonator occurs, locally and temporarily reducing the thickness of the cavity, the deformation of the resonator propagating around the central axis and leading to propulsion of a fluid admitted into the cavity around the central axis, the propulsion inducing a suction effect at the centre of the cavity facing the inlet. 
 
     
     
         2 . The pump according to  claim 1 , wherein the first transducer includes at least two distinct angular portions configured to be deformed differently under the effect of the polarisation applied to the first electrode so as to generate deformation of the first resonator propagating around the central axis. 
     
     
         3 . The pump according to  claim 2 , wherein the first electrode is segmented to form n angular sectors, n being greater than 2, the control unit being configured to polarise two angular sectors of the first electrode by respective voltages phase-shifted by a phase-shift less than or equal to 
       
         
           
             
               
                 2 
                 ⁢ 
                 π 
               
               n 
             
           
         
       
       or time-shifted by a time-shift less than or equal to 
       
         
           
             
               
                 
                   2 
                   ⁢ 
                   π 
                 
                 n 
               
               . 
             
           
         
       
     
     
         4 . The pump according to  claim 2 , wherein the first piezoelectric material includes at least two different portions in which the electric dipolar moment is oriented oppositely. 
     
     
         5 . The pump according to  claim 1 , wherein the first resonator faces a support forming a bottom of the cavity, the cavity extending between the first resonator and the bottom. 
     
     
         6 . The pump according to  claim 1 , wherein the first sleeve is coaxial with the central axis. 
     
     
         7 . The pump according to  claim 1 , wherein:
 a second annular piezoelectric transducer extends around the central axis and including a second electrode connected to the control unit;   a second resonator is connected to the second piezoelectric transducer and extends around the central axis, the second resonator being formed of a deformable solid, the second resonator becoming thinner toward the central axis, the second resonator being configured to be deformed when the second piezoelectric transducer is polarised;   the second resonator extends facing the first deformable solid material;   the cavity extends between the first resonator and the second resonator.   
     
     
         8 . The pump according to  claim 1 , wherein the second transducer includes at least two distinct angular portions configured to be deformed successively by the effect of the polarisation applied to each second electrode so as to generate deformation of the second resonator, so that the deformation of the second resonator propagates around the central axis. 
     
     
         9 . The pump according to  claim 8 , wherein the second electrode is segmented to form n angular sectors, n being greater than or equal to 2, the control unit being configured to polarise two angular sectors of the second electrode by two voltages phase-shifted by 
       
         
           
             
               
                 
                   2 
                   ⁢ 
                   π 
                 
                 n 
               
               . 
             
           
         
       
     
     
         10 . The pump according to  claim 8 , wherein the second piezoelectric material includes at least two different portions in which the electric dipolar moment is oriented oppositely. 
     
     
         11 . The pump according to  claim 10 , wherein:
 the first electrode is segmented to form angular sectors symmetrical about a first axis of symmetry and activated in phase opposition;   the second electrode is segmented to form angular sectors symmetrical about a second axis of symmetry and activated in phase opposition;   the first axis of symmetry is orthogonal to the second axis of symmetry.   
     
     
         12 . The pump according to  claim 8 , including a second sleeve connected to the second resonator and discharging at the centre of the cavity. 
     
     
         13 . The pump according to  claim 8 , wherein the second sleeve is coaxial with the central axis of the cavity. 
     
     
         14 . The pump according to  claim 1 , wherein the modulation frequency is greater than 100 kHz. 
     
     
         15 . The pump according to  claim 1 , wherein:
 the first electrode is segmented to form n angular sectors, n being greater than or equal to 2;   the control unit is configured to send a polarisation signal to each angular sector in succession;   the pump includes a control unit connected to at least one angular sector of the first electrode, the control unit being configured to detect a control signal between two successive polarisation signals.   
     
     
         16 . The pump according to  claim 1 , wherein the thickness of the cavity is less than 1 mm. 
     
     
         17 . The pump according to  claim 1 , wherein the control unit is configured to polarise the first electrode by a frequency-domain polarisation signal by carrying out a frequency sweep at a finite number of successive discrete frequencies. 
     
     
         18 . The Pump according to  claim 1 , wherein the internal surface of the cavity includes at least one hydrophobic part.