ELECTRONIC CONTROL METHOD AND SYSTEM FOR A PIEZO-ELECTRIC PUMP

• US 20130272902A1
• Filed: 12/19/2011
• Published: 10/17/2013
• Est. Priority Date: 12/23/2010
• Status: Active Grant

• Current Assignee: Debiotech S.A.
• Original Assignee: Debiotech S.A.
• Inventors: Chappel, Eric, Noth, Andr
• Granted Patent: US 9,316,220 B2
• Time in Patent Office: Days
• US Class Current: 417/53
• CPC Class Codes: F04B 43/0081 systems, control, safety measures
• CPC Class Codes: F04B 43/046 with piezoelectric drive
• CPC Class Codes: F04B 49/00 Control , e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
• CPC Class Codes: F04B 49/065 and making use of computers

Abstract

A method for actuating a pumping device with an optimal driving voltage, wherein the pumping device comprises a pumping chamber (4) having a pumping membrane (1), an inlet (3) and an outlet chamber (5), a voltage controlled actuator (6) connected to said pumping membrane (1), said pumping membrane reaching a stop position defined by a mechanical stop (2) a sensor for determining whether the pumping membrane has reached said mechanical stop (2); said method comprising a learning and working phase, wherein the learning phase comprises the following steps actuation of the pumping membrane (1) by applying a predetermined actuation voltage V_act to the actuator (6) said pumping membrane (1) reaching said position in an over-actuation step or not reaching said mechanical stop (2) position in an under-actuation process; after the over-actuation step, decreasing the voltage so that the pumping membrane (1) has left said mechanical stop (2) position and storing as the optimal voltage V_{act optimal} or in the under-actuation step, increasing the voltage so that the pumping membrane (1) reaches said mechanical stop (2) position and storing as the optimal voltage V_{act optimal} actuating the pumping device in the working phase with the determined optimal voltage value V_{act optimal}.

Claims

1. A method for actuating a pumping device with an optimal driving voltage, wherein the pumping device comprises at least

a pumping chamber having a pumping membrane an inlet chamber and an outlet chamber

a voltage controlled actuator connected to said pumping membrane said pumping membrane reaching at least one stop position defined by a mechanical stop during a pumping stroke

at least one sensor for determining whether the pumping membrane has reached said at least one mechanical stop;

said method comprising a learning phase and a working phase, wherein the learning phase comprises at least the following steps

actuation of the pumping membrane by applying a predetermined actuation voltage V_act to the actuator, said voltage being either high enough for said pumping membrane to reach said position in an over-actuation step or low enough for said pumping membrane not to reach said mechanical stop position in an under-actuation process;

after the over-actuation step, decreasing the applied actuation voltage until it is determined that the pumping membrane has left said mechanical stop position and storing as the optimal voltage V_{act optimal} the lowest applied voltage value before the pumping membrane has left said mechanical stop position;

or

in the under-actuation step, increasing the applied voltage until it is determined that the pumping membrane has reached said mechanical stop position and storing as the optimal voltage V_{act optimal} the lowest applied voltage value when the pumping membrane has reached said mechanical stop position;

actuating the pumping device in the working phase with the determined optimal voltage value V_{act optimal}.

2. A method as defined in claim 1, wherein the inlet chamber and the outlet chamber of the pumping device comprise passive valves.

3. A method as defined in claim 1, wherein after the over-actuation step

a sensor is enabled, simultaneously or not to the pumping process, to record along time one or multiple data points, forming a nominal pattern that corresponds to a nominal stroke;

for the following strokes, the actuation voltage V_Act is decreased progressively with a predefined step Δ

V,

for each decrease of actuation voltage, a measured pattern is compared to the nominal pattern, which allows detecting if the pumping membrane still reaches the at least one mechanical stops or not;

when the difference between the measured pattern and nominal pattern is higher than a defined threshold, it is determined that the pumping membrane does not reach the mechanical stop position anymore,

the last voltage value is said to be the lowest voltage leading to a correct and precise pump stroke, and it is stored as V_{act Optimal}<

V_{act Max}; and

for all the following strokes, V_{act Optimal} voltage is used, thus ensuring a minimum power consumption and an optimal pumping effect.

4. A method as defined in claim 1, wherein after the under-actuation step

after a certain time period Δ

t that ensures mechanical stabilization of the system, an increase of voltage Δ

V is applied;

simultaneously or not to the voltage increase, the sensor is enabled to record along time one or multiple data points;

these data points are then processed to determine if the voltage increase induced a displacement of the actuator;

if a displacement is sensed, this means that the mechanical stop was not reached yet because the actuator has moved following two successive voltage increase and the process restarts with an increase in voltage;

if no displacement is sensed, one concludes that the actuator has reached the mechanical stop so that voltage increases have no effect, the last voltage increase was useless, and the precedent voltage value is attributed to V_{act optimal};

for all the following strokes, V_{act Optimal} voltage (as determined above) is used, thus ensuring a minimum power consumption and an optimal pumping.

5. A method as defined in claim 3, wherein the sensor records data corresponding to flow, or to pressure in the fluidic path, or to the position of the pumping membrane or to strain on the mechanical stop, or on the pumping membrane or on the actuator.

6. A method as defined in claim 1, wherein the voltage decreasing or increasing steps vary progressively.

7. A method as defined in claim 6, wherein the initial steps a larger than the subsequent steps.

8. A method as defined in claim 1, wherein a modulation voltage is superimposed to the applied actuation voltage, wherein said modulation voltage has an amplitude at least two times smaller than the actuation voltage, wherein said modulation voltage has a frequency at least two times higher than the actuation voltage, and wherein the sensor data is monitored to evaluate its sensitivity to the modulation voltage signal such that the sensibility is high if the pumping membrane has not reached the mechanical stop and the sensibility is low if the pumping membrane has reached the mechanical stop.

9. A method as defined in claim 1, wherein the actuator (6) is a piezoelectric actuator

10. A method as defined in the claim 9, wherein the piezoelectric actuator comprises at least two actives layers, wherein the actuation voltage is applied onto the electrodes of a first active layer, wherein the modulation is applied onto the electrodes of a second active layer, wherein said modulation voltage has an amplitude at least two times smaller than the actuation voltage amplitude, and a frequency at least two times higher than the actuation voltage frequency, and wherein the sensor data is monitored to evaluate its sensitivity to the modulation voltage signal such that the sensibility is high if the pumping membrane has not reached the mechanical stop and the sensibility is low if the pumping membrane has reached the mechanical stop.

11. A method as defined in claim 1, wherein it is executed during the priming of a pump or it is repeatedly executed to take into account changes in the system.

12. A pumping device with an optimal driving voltage, wherein the pumping device comprises at least

a pumping chamber having a pumping membrane, an inlet chamber and an outlet chamber,

an actuator connected to a pumping membrane, said pumping membrane reaching at least one mechanical stop position defined by a stop during a pumping stroke

sensor(s) for determining whether the membrane has reached said at least one mechanical stop

treatment means to store and process data;

wherein said device is able to carry out the method as defined in claim 1.

13. A pumping device as defined in the claim 12, wherein the voltage controlled actuator is a piezoelectric actuator.

14. A pumping device as defined in claim 12, wherein the inlet chamber and/or the outlet chamber are/is valve(s).

15. A pumping device as defined in claim 14, wherein the valves are passive check valves.

16. A pumping device as defined in claim 12, wherein the pumping chamber has two mechanical stop.

17. A pumping device as defined in claim 12, wherein the sensor is a pressure sensor.

18. A pumping device as defined in the claim 17, wherein the sensor is a pressure sensor located within the pumping chamber.