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A high-flow, self-filling piezoelectric pump driven by hybrid connected multiple chambers with umbrella-shaped valves

Compact pumping system of large flow rate and high output pressure with self-filling are highly desired in many fields. In this study, a multi-chamber piezoelectric pump, built with unique umbrella-shaped check valves made of silica gel, is designed
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  Contents lists available at ScienceDirect Sensors and Actuators B: Chemical  journal homepage: A high- 󿬂 ow, self- 󿬁 lling piezoelectric pump driven by hybrid connectedmultiple chambers with umbrella-shaped valves Taijiang Peng a,b, ⁎ , Qiuquan Guo b, ⁎ , Jun Yang b , Junfeng Xiao b , Hao Wang a, ⁎⁎ , Yan Lou a ,Xiong Liang a a  Mechatronics and Control Engineering College of Shenzhen University, 518060, Shenzhen, China b  Mechanical and Materials Engineering Department of Western University, N6A3K7, London, ON, Canada A R T I C L E I N F O  Keywords: Check valveFluid transportation systemHybrid connected chambersPiezoelectric actuatorPiezoelectric pump A B S T R A C T Compact pumping system of large  󿬂 ow rate and high output pressure with self- 󿬁 lling are highly desired in many 󿬁 elds. In this study, a multi-chamber piezoelectric pump, built with unique umbrella-shaped check valves madeof silica gel, is designed and manufactured. The chambers are installed into two groups connected in series, andeach group consists of two chambers parallel connected, sharing the same inlet and outlet. These four chambershave the same structure, each of which is con 󿬁 gured with a piezoelectric actuator clamped by two seal rings, anda check valve severing as sub-inlet of each chamber. The  󿬂 uid comes into the inlet of the  󿬁 rst group and  󿬂 owsout through the outlet of the second group. A prototype of this kind piezoelectric pump is manufactured andassessed. The high  󿬂 ow rate up to 1845 ml/min and the output pressure of 32.47 KPa are achieved with the sinewave voltage of 210 V at the actuate frequency of 120 Hz, with the valve coe ffi cient at 0.85, and the self-suckingpressure of 15.4 KPa. 1. Introduction Piezoelectric actuation becomes a major principle for micropumpcomparing with thermopneumatic, electrostatic, and electromagneticactuation, shape memory or magnetostrictive e ff  ects [1,2] thanks to their advantages of miniature size, high reliability, large actuation forceand etc. The piezoelectric pump becomes popular and has been sub- jected to extensive attention in many  󿬁 elds since L.J. Thomas proposedan implantable micropump at 1975 [3]. Various kinds of piezoelectricpumps were invented over the last few decades [2 – 4]. Depending onthe classifying method, the piezoelectric pump can be classi 󿬁 ed intodi ff  erent categories. Considering whether there is a valve or not, it hasvalveless piezo-pump [5 – 8], active valve piezo-pump [9,10], and pas- sive valve piezo-pump [11 – 18]. For passive valves, cantilever valve[11 – 13], plate valve [14 – 17] and ball valve [18] are very commonly used as their simple structure. Currently, the small  󿬂 ow rate belowmillilitre scale is widely used in the medical system [2 – 5,19,20], which has been extensively studied, while the large  󿬂 ow rate up to hundredsmillilitre scale used for high- 󿬂 ow  󿬂 uid transportation [3,11 – 18,21 – 23]is rarely commercialized, which is highly demanded in mechanical andwarming/cooling  󿬁 elds. The typical parameters of the piezoelectricpump are shown in Table 1.Applications such as hemodialysis machine, water cooling systemfor chips, and coolant transportation for machine tooling often need apump with high- 󿬂 ow  󿬂 uid transportation. In addition, the pump re-quires a compact structure, self- 󿬁 lling capability, and high pressure forbetter accommodation. Due to the intrinsic limitation of small de-formation for a piezoelectric disk, the volume change of a chamber islimited. Considering the various advantages of the piezoelectric pump,it is imperative to break such bottleneck. An e ffi cient solution for thelarge  󿬂 ow rate is to increase the number of chambers [21 – 23] and thevibrating frequency of the piezoelectric disk. However, the highworking frequency of a piezoelectric pump is often not preferred, whichis determined by many factors as it is a complicate  󿬂 uid-solid couplingsystem, and impacted by the characteristics of the piezoelectric ac-tuator, the dynamic of the check valve, chamber structure, and  󿬂 uidcharacteristics. Especially, a high sti ff  ness check valve can ’ t act im-mediately when the chamber volume starts to change caused by thevibrating of the piezoelectric actuator. Dong [23] Proposed a pumpwith dual vibrators at the axis and four plate valves, the pump can workat the model of asynchronous or synchronous and its maximum  󿬂 owrate up to 1678.2ml/min. But there are two check valves glued on the 11 May 2019; Received in revised form 5 August 2019; Accepted 7 August 2019 ⁎ Corresponding author at: Mechanical and Materials Engineering Department of Western University, N6A3K7, London, ON, Canada. ⁎⁎ Corresponding author at: Mechatronics and Control Engineering College of Shenzhen University, 518060, Shenzhen, China.  E-mail addresses: (T. Peng), (Q. Guo), (H. Wang). Sensors & Actuators: B. Chemical 301 (2019) 126961Available online 03 September 20190925-4005/ © 2019 Elsevier B.V. All rights reserved.    center hole of the piezoelectric disk, the process is unsuitable for vo-lume production, and it has the risks of low-yield and short-lifetime.Therefore, developing a robust and reliable check valve system is cri-tical for a multiple chamber pumping system.In this manuscript, an innovative hybrid connected multiple-chamber piezoelectric pump with umbrella-shaped valves was pro-posed, the valve is made of silica gel and mounted at the sub-inlet of thechambers. Unlike the similar traditional pumps, two groups of double-chamber connected in parallel  󿬁 rst and then connected in serial to forma hybrid con 󿬁 guration, which has the peristalsis actuate principle forhigh- 󿬂 ow  󿬂 uid transport application. Each chamber con 󿬁 gured with anumbrella-shaped check valve, serving as the sub-inlet switch. As thevalve performance is vital for pump capability, several di ff  erent kindsof check valve were assessed for the better choice. A prototype of theproposed pump with umbrella-shaped valve was manufactured. Withthe sine wave voltage of 210V at the frequency of 120Hz, the max-imum  󿬂 ow rate up to 1845ml/min, which is one of the highest  󿬂 owrates in literature at present. Moreover, the output pressure can reach32.47KPa, which is also important for various applications. The pumpis designed to have the self- 󿬁 lling capability, the self-sucking pressureup to 15.4KPa. All these characteristics are important and rarelyachieved for commercial piezoelectric pump systems. 2. Design and working principle A symmetrical multiple chambers piezo-pump con 󿬁 guration modelis shown in Fig. 1. Two symmetrical pump bodies with two serialchambers are connected in parallel, forming a hybrid four-chamberpump system. Each chamber is con 󿬁 gured with one piezoelectric ac-tuator, one passive umbrella-shaped valve as the switch of the sub-inlet,two silicon rubber sealing rings clamping the piezoelectric actuator onboth sides. Each of the pump body installed with two valves  󿬁 rst andthen welded back to back by ultrasonic welding machine. Two coverswith the sealing ring clamping the piezoelectric actuator and then as-sembled the pump by bolts and nuts.The electrode connection of the piezoelectric actuators is illustratedin Fig. 2. The four piezoelectric actuators have the same structurecon 󿬁 guration with the same polarization direction. One signal wire waswelded on piezoelectric ceramic disk with a diameter of 28mm, and theother signal wire was welded on the metal disk made by copper with adiameter of 35mm. The wires at the pump unit 1/2 connected with thecounterparts respectively  󿬁 rst, and then cross-connected to be the twoelectrodes of the pump, they connected with the signal generator pro-vide the needed exciting signal such as a sinusoidal wave. According tothe inverse piezoelectric e ff  ect, the chambers at unit 1/2 connected inparallel means that they have the same inlet and outlet respectively,and the two piezoelectric actuators of the same unit are excited by thesame signal to produce vibration, so that the volume of the corre-sponding chambers become larger or smaller at the same time. The two-chamber groups connected in serial means that the outlet of unit 1 actsas the inlet of unit 2, and the volume of the two-chamber groupschanged opposite, one became larger and the other became smaller.The working principle of this proposed pump system is demon-strated in Fig. 3. As mentioned above, the vibrating of the piezoelectricactuators at unit 1 makes the chambers A and C expanded or constrictedat the same time, but the opposite action at unit 2. When the chambervolume expanded and has enough negative pressure to make the checkvalve opened, the  󿬂 uid sucked into the chambers, meanwhile, thechamber volume constricted and has enough positive pressure to makethe check valve closed, the  󿬂 uid pumped out. At the  󿬁 rst-half period,the chambers A and C expanded, the chambers B and D constricted, thevalves in unit 1 will be opened, and the valves in unit 2 will be closed,the  󿬂 uid is sucked into the chambers A and C, and pumped out from thechambers B and D; at the second-half period, the volume change pro-cess of the chambers is opposite to the  󿬁 rst-half period, so the  󿬂 uid ispumped out from the chambers A and C, and sucked into the chambers       T     a       b       l     e      1     T   y   p    i   c   a     l   p   a   r   a   m   e    t   e   r   c   o   m   p   a   r    i   s   o   n   o     f    t     h   e   p    i   e   z   o   e     l   e   c    t   r    i   c   p   u   m   p .     R   e     f .    A   u    t     h   o   r    Y   e   a   r    M   a   x    F     l   o   w    R   a    t   e    (   m     l    /   m    i   n    )    M   a   x    O   u    t   p   u    t    P   r   e   s   s   u   r   e    (    P   a    )    F   r   e   q   u   e   n   c   y    (    H   z    )    H    i   g     h     l    i   g     h    t   s    [    4    ]    Q .    C   u    i   a   n     d   e    t   c .    2    0    0    7    9 .    0    ×    1    0    −        2     /    4    0    0    V   a     l   v   e     l   e   s   s   m    i   c   r   o   p   u   m   p   w    i    t     h     d    i       ff    u   s   e   r    /   n   o   z   z     l   e   e     l   e   m   e   n    t   s     f   o   r     d   r   u   g     d   e     l    i   v   e   r   y   s   y   s    t   e   m .    [    5    ]    H .    K .    M   a   a   n     d   e    t   c .    2    0    1    0    6    7 .    9    8    1 .    3    6    6    ×    1    0        3     1    5    0    O   n   e  -   s    i     d   e   a   c    t   u   a    t    i   n   g   v   a     l   v   e     l   e   s   s   m    i   c   r   o   p   u   m   p   w    i    t     h     d    i       ff    u   s   e   r    /   n   o   z   z     l   e   e     l   e   m   e   n    t .    [    7    ]    J .    H   u   a   n   g   a   n     d   e    t   c .    2    0    1    4    2    9 .    1    6    6 .    3    7    ×    1    0        2     1    3    V   a     l   v   e     l   e   s   s   p    i   e   z   o   e     l   e   c    t   r    i   c   p   u   m   p   w    i    t     h     f   r   a   c    t   a     l  -     l    i     k   e    Y  -   s     h   a   p   e     b   r   a   n   c     h    i   n   g    t   u     b   e   s    [    9    ]    H .    K .    M   a   a   n     d   e    t   c .    2    0    1    5    1    9    6    /    2    5    P    i   e   z   o   e     l   e   c    t   r    i   c   p   u   m   p   w    i    t     h   p     l   a    t   e   c     h   e   c     k   v   a     l   v   e   a   n     d   r    i     b   c     h   a   m     b   e   r   s    t   r   u   c    t   u   r   e     f   o   r     b    i   o   m   e     d    i   c   a     l   a   p   p     l    i   c   a    t    i   o   n .    [    1    1    ]    J .    K   a   n   a   n     d   e    t   c .    2    0    0    5    3 .    5    2 .    7    ×    1    0        4     2    0    0    P    i   e   z   o   e     l   e   c    t   r    i   c   p   u   m   p   w    i    t     h   m   e    t   a     l   c   a   n    t    i     l   e   v   e   r  -   v   a     l   v   e     f   o   r     d   r   u   g     d   e     l    i   v   e   r   y .    [    1    2    ]    N .    J .    G   r   a     f   a   n     d   e    t   c .    2    0    0    8    5 .    7    5    ×    1    0    −        4     3 .    6    8    ×    1    0        4     2    5    A   s   o     f    t  -   p   o     l   y   m   e   r   p    i   e   z   o   e     l   e   c    t   r    i   c     b    i   m   o   r   p     h   c   a   n    t    i     l   e   v   e   r  -   a   c    t   u   a    t   e     d   p   e   r    i   s    t   a     l    t    i   c   m    i   c   r   o   p   u   m   p   w    i    t     h   a     l   u   m    i   n   u   m   v   a     l   v   e   s   o     f    3   m   m    ×    2    0    0       μ    m    (    L    ×    W    ) .    [    1    4    ]    P .    Z   e   n   g   a   n     d   e    t   c .    2    0    1    6    3    1    8    4 .    0    5    ×    1    0        4     1    3    0    A   s    i   n   g     l   e  -     b    i   m   o   r   p     h     d   o   u     b     l   e  -   a   c    t    i   n   g   c     h   e   c     k  -   v   a     l   v   e   p    i   e   z   o   e     l   e   c    t   r    i   c   p   u   m   p   w    i    t     h    t   w   o   s   e   r    i   a     l  -   c   o   n   n   e   c    t   e     d   c     h   a   m     b   e   r   s .    [    2    3    ]    J .    S .    D   o   n   g   a   n     d   e    t   c .    2    0    1    8    1    6    7    8 .    2    2 .    1    8    ×    1    0        3     2    4    0   a   p    i   e   z   o   e     l   e   c    t   r    i   c   p   u   m   p   w    i    t     h     d   u   a     l   v    i     b   r   a    t   o   r   s   a    t    t     h   e   a   x    i   s   a   n     d   w     h   e   e     l   v   a     l   v   e   s . T. Peng, et al.  Sensors & Actuators: B. Chemical 301 (2019) 126961 2  B and D. As the  󿬂 uid has velocity inertia at the  󿬁 rst-half period, the 󿬂 uid can ’ t be sucked back into chambers B and D from the outlet of thepump. There are valves set at the inlet and outlet of the chambers A andC, which makes the pump has better self-suck ability and high outpressure.Based on the theory of  󿬂 uid mechanics [24] and piezoelectric theory[25], the  󿬂 ow rate of the pump can be calculated as = ∙ ∙ = ∙ ∙ ∙ ∙ ∙ ∙ C V f c d Dt U f  Q 2 2 ∆ 2 2 38 v v  3122 (1)Where C  v  -the valve coe ffi cient as it's delay response to the vibration of apiezoelectric disk; V  ∆  - the volume deformation of the piezo disk,  m 3 ; d 31  -the piezoelectric constant of the piezoelectric ceramic,  m V  /  ; D  - the diameter of the piezoelectric disk,  m ; t   - the thickness of the piezoelectric disk,  m ; U  - the exciting voltage,  V  ;  f   - the working frequency of the pump,  Hz  .The  󿬂 uid pressed by piezoelectric disk at unit 1 chambers and thentransport into unit 2 chambers, after repressed and then  󿬂 owed out, theoutput pressure of the pump can be calculated as [24] = ∙ ∙ Q C A P 2ρ ( / ) d 2 (2)Where  ρ  - the density of the  󿬂 uid,  kg m /  3 ; C  d  - the  󿬂 ow rate coe ffi cient;  A  - the minimum sectional area of the  󿬂 uid passageway,  m 2 . 3. Valve performance assessment The valve is one of the key parts used in piezoelectric pump, thecommon used passive valve such as cantilever valve, plate valve andball valve, many of this kind pump proposed at present [11 – 18] withdi ff  erent performance, since the valves have di ff  erent sti ff  ness anddynamic capability, it makes them have di ff  erent open pressure andswitch speed. As mentioned above, the passive valve couldn't act im-mediately when the chamber volume changed. It is di ffi cult to measurethe delay time to assess the dynamic of the passive check valve. Asystem is shown in Fig. 4 used to measure the open pressure and static 󿬂 ow rate of the passive check valve in the same circumstance to chosethe proper valve.Four check valves were fabricated for mounted in the compactproposed piezo-pump and involved in the contrast assessment. Thecantilever valve and the plate valve were made of copper with thethickness of 0.3mm, the ball valve includes a ceramic ball with thediameter of 4mm and a spring, an umbrella-shaped valve made of silicagel and the diameter of 10mm and the thickness of 0.3mm, all thevalve seats have the same size about the inlet and the outlet, and alsohave the same throttling area about 7.06 mm 2 , but they have di ff  erenttransportation capability as their di ff  erent valve open degree. Thepiezo-Pump transport water into a cup with a switch to adjust the  󿬂 owrate of the piezo-pump. When the water  󿬂 ows out from the valve seatand the height  ∆h  was recorded as the start open pressure of the valve.And next, the piezo-pump was adjusted to keep the height  ∆h  stabilizedat a certain level to record the  󿬂 ow rate. The result is shown in Fig. 5.The static open pressure is 0.4KPa, 0.7KPa, 1.2KPa and 1.8KParespectively, and the maximum static  󿬂 ow rate is 64ml/min, 58ml/min, 53ml/min and 32ml/min under the pressure of 1.3KPa, 1.9KPa,2.1KPa, and 2.2KPa respectively, corresponding to umbrella-shapedsilicon valve, plate valve, cantilever valve and ball valve in turn. So, theumbrella-shaped silicon valve has a lower open pressure and easier toopen or close. The cantilever valve and the plate valve are normallyglued to  󿬁 x [11 – 17] with the risk of fatigue ageing of the glue, whichwill cause to shorten the lifetime of the pump and a ff  ect the sealingcapability of the switch, the ball valve couldn't compact to simplify thestructure of the multi-chamber pump. The umbrella-shaped silica valvehas the advantages of good sealing capability, long fatigue life, easy to 󿬁 x, compactable, easy to mass manufacturing and better static perfor-mance, it is the best choice for building the proposed pump under the Fig. 1.  Explosive view of the assembled piezo-pump and the prototype. Fig. 2.  Schematic of the electrode connection. T. Peng, et al.  Sensors & Actuators: B. Chemical 301 (2019) 126961 3  same circumstance. 4. Pump performance tests A prototype of the proposed pump stated as Fig. 1 has been man-ufactured. The piezoelectric actuator is the key part and clamped bytwo silicon sealing rings, its amplitude a ff  ects the performance of thepump as shown in Eq. (1), the relationship between the amplitude andthe voltage, the frequency of the exciting signal was measured, and theresult is shown in Fig. 6.The amplitude measured by a laser vibrating meter (Type: LK-G5000) made by Keyence, Japan. The laser spot is located at the centerof the disk. The two sealing rings act as a spring to enlarge the ampli-tude and each tightened with 0.3mm compression deformation. Theresult showed that the pump can work at the frequency from 60Hz to140Hz with stable performance, and this is the direct way to  󿬁 nd outthe working frequency of the pump, and also it provides the method toadjust the performance of the pump to change the voltage or the fre-quency of the excite signal.Next, the  󿬂 ow rate, output pressure without  󿬂 ow and the self-suckability were measured by the platform shown in the Fig. 7. the piezopump connected with a pressure gauge and a 󿬂 ow meter by a three-waypipe with two switches, and the height from the piezo pump to the tankcan be adjusted to determine the highest self-suck pressure with no 󿬂 uid 󿬂 ow out, a power supply can generate sinusoidal signal, its voltage Fig. 3.  Working principle of the piezo-pump. Fig. 4.  The static performance measuring system of the check valve. Fig. 5.  Static performance of the check valves. T. Peng, et al.  Sensors & Actuators: B. Chemical 301 (2019) 126961 4  and frequency can be adjusted for the pump needed. The  󿬂 uid is waterduring these tests.The results shown as Fig. 8 to 10 as the relationships between  󿬂 owrate, output pressure, self-suck ability and excite signal respectively, the 󿬂 ow rate and the output pressure measured at  = h 100mm  for thecommon application. as if the more height the more energy consump-tion for suck in leads to the less 󿬂 ow rate and the lower output pressure.From Fig. 8, the larger  󿬂 ow rate work point located at 120Hz wherethe piezoelectric disk has larger amplitude, and the  󿬂 ow rate is1845ml/min with the voltage of 210V. As the delay response of thecheck valve, the  = ∼ C   0.35 0.85 v  at a di ff  erent working frequency fromEq. (1), it is about 0.85 when the working frequency is 120Hz, and it islower at other frequency as the lower negative pressure to actuate thecheck valve with the less deformation. From Fig. 9, the higher outputpressure at the lower  󿬂 ow rate, due to the input energy can be assumedas constant with a certain excite signal. The lowest output pressure isabout 32.47KPa and the highest output pressure is about 43.98KPa.From Fig. 10, the highest self-suck height presented at the largest am-plitude, as the larger negative pressure resulted by the larger de-formation of the chambers. The highest self-suck height is about 1.54m(it is equal to about 15.4KPa) with 120Hz, 210V excite signal, and thelower height is about 1.16m (about 11.6KPa) with 40Hz, 120V excitesignal.As the piezoelectric pump is a complicated  󿬂 uid-solid couplingsystem, it is a ff  ected by the performance of the piezoelectric disk, dy-namic capability of the check valve, chamber structure,  󿬂 uid viscosityand other factors, the  󿬂 ow rate and the output pressure are linear withthe voltage of the excite signal, but nonlinear with the frequency of theexcite signal because of the valve coe ffi cient, the dynamic of   󿬂 uid-solidcoupling and the characteristic of the piezoelectric actuator. This pro-posed pump should be working at the best parameter with the fre-quency of 120Hz, the  󿬂 ow rate and output pressure should be adjustedby change the excite voltage determined by the control system.Furthermore, if the voltage is too high, the piezoelectric ceramic diskwill be fractured easily; the voltage is too low, and the vibration of thepiezoelectric actuator is not enough to actuate the pump to work.Therefore, the proper voltage of the proposed pump is 120VAC to210VAC and at the frequency from 60Hz to 140Hz can ensure thepump works in good condition. Fig. 6.  Relationship between amplitude and excite voltage and frequency. Fig. 7.  Piezo pump performance measurement platform. Fig. 8.  Relationship between  󿬂 ow rate and excite signal. Fig. 9.  Relationship between output pressure with relation to the voltage andfrequency of the excite signal. Fig. 10.  Relationship between self-suck pressure and excite signal. T. Peng, et al.  Sensors & Actuators: B. Chemical 301 (2019) 126961 5
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