采用壓電蜂鳴器設(shè)計(jì)和啟用壓電離合器?【中文6190字】【PDF+中文WORD】,中文6190字,PDF+中文WORD,采用,壓電,蜂鳴器,設(shè)計(jì),啟用,離合器,中文,6190,PDF,WORD 【中文6190字】 采用壓電蜂鳴器設(shè)計(jì)和啟用壓電離合器 摘要 本文開(kāi)發(fā)了一種新型的壓電離合器機(jī)構(gòu)，包括駕駛驅(qū)動(dòng)件和從動(dòng)件，并研究了離合器機(jī)構(gòu)的離合性能。每個(gè)部分都是基于一個(gè)薄盤(pán)壓電蜂鳴器作用下耦合模式的摩擦件和一個(gè)在非耦合模式的機(jī)械振動(dòng)機(jī)構(gòu)。首先表達(dá)出離合器機(jī)構(gòu)和它的實(shí)驗(yàn)裝置，即一個(gè)電力傳輸系統(tǒng)。然后，操作原則，用于分離的兩個(gè)相對(duì)表面上的逆壓電效應(yīng)和超聲懸浮聲明，并用于引入觀察該壓電蜂鳴器的振動(dòng)模式的碳粉末的成像方法。此外，一個(gè)DC / AC諧振逆變器，用于將直流電源的正弦源施加以激勵(lì)壓電蜂鳴器構(gòu)成。最后，對(duì)轉(zhuǎn)速和電氣條件，以及與改變狀態(tài)的轉(zhuǎn)速的瞬 態(tài)響應(yīng)之間的關(guān)系進(jìn)行了研究。 關(guān)鍵詞：壓電式離合器；壓電式蜂鳴器；振動(dòng)模式；壓電效應(yīng)。 1．介紹 傳統(tǒng)的離合器，其中包括電磁離合器，齒輪離合器，摩擦離合器，超越離合器和離心離合器，通常用于啟動(dòng)或停止機(jī)械加載，甚至控機(jī)械的轉(zhuǎn)速加載中電力傳輸系統(tǒng)。電磁離合器用于一些磁性粉末具有磁通聯(lián)系。由激勵(lì)線圈包圍需要傳遞轉(zhuǎn)矩從磁化后，開(kāi)端到從動(dòng)端發(fā)送的轉(zhuǎn)矩近似正比于磁場(chǎng)或磁化電流。每個(gè)電磁離合器在相同的速度或可控制的速度差下能夠連接的驅(qū)動(dòng)和從動(dòng)件。不幸的是，任何電磁離合器有其固有的缺點(diǎn)，如大的電磁干擾（EMI），這是不利在免費(fèi)的EMI的地點(diǎn)運(yùn)行，如醫(yī)院或精密實(shí)驗(yàn)室的離合器[1-4]。對(duì)于齒輪離合器，如突起齒輪或鍵內(nèi)置在驅(qū)動(dòng)和從動(dòng)件。由主動(dòng)和從動(dòng)之間速度的大小所不相同，以避免過(guò)度的沖擊或損壞被測(cè)的耦合齒輪離合器和非耦合模式[5-8]。為摩擦離合器，主動(dòng)和從動(dòng)構(gòu)件相互連接并互相摩擦，從而使驅(qū)動(dòng)件來(lái)驅(qū)動(dòng)從動(dòng)構(gòu)件。他們迅速通過(guò)一個(gè)小的沖擊力還是有點(diǎn)震動(dòng)連接或分離。但是，磨料滑移的部件的接觸是由一個(gè)重負(fù)載，縮短離合材料的耐久性或保持經(jīng)常的保養(yǎng)[9-11]。對(duì)于超速離合器，一個(gè)超越離合器包括棘輪，棘爪，旋轉(zhuǎn)缸和楔形塊。其施工簡(jiǎn)便，是離合器用其所述驅(qū)動(dòng)扭矩或運(yùn)動(dòng)傳遞到的從動(dòng)結(jié)束在單向方向。但在一個(gè)相當(dāng)龐大的規(guī)模，并在瞬間產(chǎn)生的巨響中從耦合到非耦合，由于成員矩模式限制，這種類(lèi)型的機(jī)制只能適用于中低速和非精密機(jī)器[12,13]。 離心離合器，如果其駕駛所需的速度達(dá)到驅(qū)動(dòng)的接觸，從動(dòng)部件會(huì)通過(guò)一個(gè)分離離心力的作用自動(dòng)連接。則該離合器具有相當(dāng)笨重的機(jī)構(gòu)[14,15]。在解決對(duì)于上述傳統(tǒng)的離合器問(wèn)題上，對(duì)于超聲波離合器驅(qū)動(dòng)力控制設(shè)備與被動(dòng)力反饋控制已經(jīng)發(fā)展[16]。而且，超聲波離合器，包括兩個(gè)超聲波換能器機(jī)械振動(dòng)器，用于控制驅(qū)動(dòng)之間的接觸或非接觸[17]。 基于上述情況，本文開(kāi)發(fā)了一種新的壓電離合器機(jī)構(gòu)，包括兩個(gè)薄盤(pán)壓電蜂鳴器機(jī)械振動(dòng)器和摩擦件，以減少離合機(jī)構(gòu)，取消了電磁干擾的影響，從耦合瞬態(tài)沖擊非耦合模式，并控制由驅(qū)動(dòng)傳遞到從動(dòng)端的功率。 2．機(jī)制設(shè)計(jì) 如圖1. 壓電離合器機(jī)構(gòu)包含一個(gè)驅(qū)動(dòng)件和一個(gè)從動(dòng)件，其中每個(gè)都包含薄盤(pán)壓電式蜂鳴器（TE41208-26，Seahorn公司，臺(tái)北，臺(tái)灣），驅(qū)動(dòng)或從動(dòng)軸，一個(gè)塑料固定器和兩個(gè)電線。壓電式蜂鳴器包括一個(gè)壓電陶瓷盤(pán)（直徑，24.8毫米;厚度0.1毫米），鎳合金盤(pán)（直徑41.0毫米;厚度0.1毫米）和鍍銀電極（直徑，24.8毫米;厚度0.02毫米） 圖1.壓電式離合器機(jī)構(gòu) 如圖所示。2.壓電陶瓷盤(pán)有極化方向和厚度方向。壓電的質(zhì)量蜂鳴器是約1.5g。用于電驅(qū)動(dòng)器，電正弦波源通過(guò)鎳合金盤(pán)和鍍銀電極提供給壓電，如圖2所示。3. 在離合器機(jī)構(gòu)的組裝中，導(dǎo)電抽頭是附著在塑料固定器的外部。該從動(dòng)軸驅(qū)動(dòng)的軸對(duì)齊。壓電式蜂鳴器由粘膠在一個(gè)節(jié)圓固定在塑料固定器的邊緣的鎳合金盤(pán)上的振動(dòng)模式。對(duì)于電線，1被安裝在鍍銀電極驅(qū)動(dòng)軸之間，而另一個(gè)被安裝導(dǎo)電水龍頭及鎳合金磁盤(pán)之間。圖 4. 電力傳輸系統(tǒng)包括離合器機(jī)構(gòu)，電氣控制系統(tǒng)，2預(yù)壓控制器，兩個(gè)塑料接頭，及其他。電氣控制系統(tǒng)包括一個(gè)AC電源系統(tǒng)中兩個(gè)開(kāi)關(guān)S1和S2中，兩個(gè)導(dǎo)電的水龍頭，碳刷，和一個(gè)原基地。本系統(tǒng)是用來(lái)控制電驅(qū)動(dòng)條件成員，并確定耦合的或非耦合離合器機(jī)構(gòu)的模式。每個(gè)預(yù)緊控制器包含不銹鋼彈簧，兩個(gè)金屬墊圈和一個(gè)線性軸承，當(dāng)墊圈安裝在彈簧的兩端，并且該軸承是需要支持和引導(dǎo)驅(qū)動(dòng)或從動(dòng)沿著所述離合器機(jī)構(gòu)的中心軸線。該控制器提供預(yù)加載力來(lái)驅(qū)動(dòng)或從動(dòng)構(gòu)件，以確保其相對(duì)表面彼此連接在耦合模式。提供的規(guī)格彈簧，塑性系數(shù)為約1.15克/厘米，長(zhǎng)度為大約18毫米，直徑約為4毫米。因此，在對(duì)向面接觸的預(yù)加載力約0.46克。在塑料接頭的連接時(shí)，其中一個(gè)所述驅(qū)動(dòng)軸與電動(dòng)機(jī)之間連接的軸，另一個(gè)是從動(dòng)軸和一個(gè)之間連接的負(fù)載軸。 圖2壓電蜂鳴器結(jié)構(gòu) 圖3壓電蜂鳴器驅(qū)動(dòng) 圖4電力傳輸系統(tǒng) 圖5逆壓電效應(yīng) 圖 6近場(chǎng)聲懸浮 圖7碳粉成像方法原理：（a）粉末運(yùn)動(dòng)（b）電荷分布 圖 8振動(dòng)模式模式：（a）前視圖模式;（b）背面視圖模式 3．工作原理 離合器機(jī)構(gòu)的非耦合模式是基于近場(chǎng)聲懸浮[18?20]，這是造成逆壓電效應(yīng)。稱(chēng)為逆壓電效應(yīng)，壓電元件的形狀由一個(gè)正延伸直流驅(qū)動(dòng)電壓和一個(gè)負(fù)的直流驅(qū)動(dòng)電壓，如圖5中所示。關(guān)于聲懸浮，一個(gè)對(duì)象，具有一個(gè)平面和剛性底部暫停。上述一個(gè)使用輻射的壓電振子的輻射表面在物體的底部，以及一個(gè)壓力Π（kgw/m2）活塞狀聲波發(fā)生在磁懸浮之間的空間對(duì)象和所述輻射表面，如在圖6中描繪。通常，在懸浮高度比波長(zhǎng)小得多的聲波。 圖9前視圖模式的三維視角 這個(gè)高度h（M），表示由其中a0是振動(dòng)振幅（米），ρa(bǔ)為聲密度中等（kg/m3的）,ca是介質(zhì)的聲速（m/s），以及γ是比熱比[21]。 用公式。 （1），該與振動(dòng)振幅懸浮高度增加，如果參數(shù)如ρA，CA，γ和Π是恒定的。此外，的離合器機(jī)構(gòu)的結(jié)果的非耦合模式在很大程度上從聲懸浮，使從動(dòng)軸停止，但是驅(qū)動(dòng)軸仍然在旋轉(zhuǎn)。 圖10原理振動(dòng)模式 圖11交流供電系統(tǒng) 圖12速度測(cè)量系統(tǒng) 圖?13速度與在76.0千赫的頻率的直流輸入電壓 圖 14 在不同電壓下的速度與頻率的關(guān)系：（a）Vdc =1，2，3V;（b）Vdc =4，5，6V;（c）Vdc =7，8，9V;（d）Vdc =10，11，12V 從圖1和4所示，構(gòu)件被布置成一個(gè)公共的旋轉(zhuǎn)軸，是在第一狀態(tài)下相互接觸，如果成員都在低壓電蜂鳴器低交流電源供電，這些成員是進(jìn)一步移動(dòng)到第二狀態(tài)，從而在驅(qū)動(dòng)件被斷開(kāi)使用強(qiáng)大的輻射壓力從動(dòng)件字段壓電蜂鳴器的面對(duì)的表面上，如果一個(gè)或兩個(gè)成員在壓電蜂鳴器被通到高壓AC電源。如果必要時(shí)，兩個(gè)成員可以互換彼此。然后，對(duì)接觸面構(gòu)件緊密耦合在一起而沒(méi)有電激勵(lì)壓電蜂鳴器，以便得到一個(gè)事實(shí)，即驅(qū)動(dòng)部件驅(qū)動(dòng)所述從動(dòng)構(gòu)件，這些表面還阻隔了斷開(kāi)的成員，從而停止從動(dòng)構(gòu)件，但仍然旋轉(zhuǎn)的驅(qū)動(dòng)部件，如一個(gè)或兩個(gè)壓電蜂鳴器由高AC電激勵(lì)電源。 4．機(jī)械分析 振動(dòng)的電模式通電壓電蜂鳴器是由一個(gè)碳-粉末觀察成像方法，以闡明之間的斷線面向構(gòu)件的表面。操作該成像方法中，首先，一些碳的粉末在兩側(cè)均勻地?cái)U(kuò)展的壓電式蜂鳴器。然后，該粉末從移動(dòng)環(huán)路中的軸對(duì)稱(chēng)彎曲振動(dòng)的節(jié)點(diǎn)壓電蜂鳴器，如圖所示.7（a），直到露出振動(dòng)模式的后電接通。由于正電荷和負(fù)電荷由殘余電場(chǎng)引起的振動(dòng)，其模式仍保持在兩側(cè)壓電蜂鳴器，如圖所示.7（b）所示，。此外，該振動(dòng)模式的圖案在壓電蜂鳴器的兩側(cè)被描繪在圖8（a）及（b）如果在壓電蜂鳴器通過(guò)通電正弦波源，涉及5V的幅度和73.25 kHz的頻率。在圖案，深色區(qū)域代表振動(dòng)模式的節(jié)點(diǎn)，并且明亮區(qū)域表示的環(huán)振動(dòng)模式。從圖9所示，第一結(jié)圈，φN1的直徑是約5.9毫米，所述第二直徑節(jié)圓，φN2，是約14.0毫米，直徑第三個(gè)節(jié)點(diǎn)的圓，φn3，是約21.2毫米。例如一個(gè)薄盤(pán)壓電蜂鳴器是一個(gè)薄盤(pán)的下面，一個(gè)二維（2D）的波動(dòng)方程壓電元件，定義如下 這里，u是振幅，r是半徑，θ是幾何角，c為聲速，T是橫張力，ρ為質(zhì)量密度。因此，c為常數(shù)如果T和ρ是恒定的。變量θ為進(jìn)一步與由式得出。 （2）由于給壓電蜂鳴器的軸向?qū)ΨQ(chēng)模式。因此，二維波動(dòng)方程的解包含零級(jí)的任期第一種貝塞爾函數(shù)J0和歐拉函數(shù)的一個(gè)術(shù)語(yǔ)ejωt如果壓電蜂鳴器是由一個(gè)電正弦電源激勵(lì)。 該解決方案表示機(jī)械振動(dòng)是由以下表示，Am進(jìn)行振動(dòng)的振幅，k是波數(shù)，λ為波長(zhǎng)，ω是角頻率。示意性的振動(dòng)模式的示意圖顯示于圖10。此外， φn1 : φn2 : φn3 = α01: α02: α03, 通過(guò)計(jì)算：α01～=2.4,α02～=5.6, 和α03～=8.6，在α01，α02和α03是：零階第一的貝塞爾函數(shù)的第二和第三零J0，分別為[23]。這一發(fā)現(xiàn)表明，式（3）可用于分析所述壓電陶瓷的振動(dòng)行為的一部分。因此，軸向?qū)ΨQ(chēng)彎曲振動(dòng)模式幾乎主宰了壓電振動(dòng)行為在自由邊界條件蜂鳴器因?yàn)橹睆溅?大大超過(guò)了在壓電陶瓷的厚度t2的磁盤(pán)[24]。此外，φ2/t2=248，由φ9=24.8毫米計(jì)算，并且T2= 0.1毫米。 5.實(shí)驗(yàn)裝置 用于產(chǎn)生電的正弦交流電源系統(tǒng)源在壓電蜂鳴器的輸入端子示出圖. 11。這個(gè)系統(tǒng)包括一個(gè)DC / AC諧振逆變器，一個(gè)驅(qū)動(dòng)和隔離電路，直流電源（LPS305，美國(guó)依賴(lài)公司，EI的Monte，CA）和一個(gè)函數(shù)發(fā)生器（FG506，美國(guó)依賴(lài)公司，EI的Monte，CA）中的諧振坦克由一個(gè)串聯(lián)電感LF（?=的64ΔH）和一個(gè)平行電容Cf（?=0.1uF）。諧振逆變器包含一個(gè)全橋菜刀有四個(gè)MOSFET器件（IRF840，Unitrode公司公司，達(dá)拉斯，德克薩斯州）中，諧振回路和等效電路 壓電蜂鳴器。MOSFET器件被控制由四個(gè)矩形觸發(fā)信號(hào)VGS1 - VGS4，分別是從驅(qū)動(dòng)和隔離電路產(chǎn)生并由函數(shù)。脈沖寬度調(diào)制控制信號(hào)VPWM作為驅(qū)動(dòng)和隔離電路的輸入信號(hào)從函數(shù)發(fā)生器產(chǎn)生。因此，振幅正弦源是由直流電源控制，并且正弦信號(hào)源的頻率是由功能控制發(fā)電機(jī)。從圖12，一個(gè)速度測(cè)量系統(tǒng)，包括兩個(gè)數(shù)字光學(xué)轉(zhuǎn)速計(jì)（RM-1501，PROVA公司，臺(tái)北，臺(tái)灣）和兩個(gè)光反射，是量度在構(gòu)件的軸的旋轉(zhuǎn)速度。每個(gè)反射器是附著在該驅(qū)動(dòng)的塑料固定器的外側(cè)。 6.結(jié)果與討論 根據(jù)圖4，在驅(qū)動(dòng)壓電蜂鳴器構(gòu)件是通過(guò)在正弦電源電激勵(lì)76.0千赫，它是諧振頻率相同的頻率使用不同的電壓，從而控制壓電蜂鳴器由圖11中所示的直流電源。電源正弦振幅約與DC增加輸入電壓，如果驅(qū)動(dòng)頻率是恒定的。從圖13的驅(qū)動(dòng)速度指示驅(qū)動(dòng)軸的速度幾乎等于驅(qū)動(dòng)速度指示所述從動(dòng)軸的速度為離合器機(jī)構(gòu)的聯(lián)接方式，如果一個(gè)低直流輸入電壓（≤7V）被提供。每個(gè)速度從20變23 RPS。在這里，RPS表示每秒改變。此外，該行駛速度可達(dá)29 RPS和驅(qū)動(dòng)速度下降為離合器機(jī)構(gòu)的非耦合模式零，如果高直流輸入電壓（≥8V）被提供。因此，如果驅(qū)動(dòng)頻率是恒定的，函數(shù)從耦合到非耦合方式的離合器機(jī)構(gòu)通過(guò)增加直流輸入電壓或振幅增強(qiáng)正弦源的。 圖15 使用VDC =12V和驅(qū)動(dòng)速度的測(cè)量瞬態(tài)響應(yīng)F =變化在不同條件下76.0千赫：（a）從所述非接觸聯(lián)系方式;（b）從接觸到非接觸模式 然后，均對(duì)速度的驅(qū)動(dòng)頻率的影響。從圖14（a）-（d）中，主動(dòng)和從動(dòng)速度幾乎不受驅(qū)動(dòng)頻率從70到80千赫和驅(qū)動(dòng)速度大致相當(dāng)于從動(dòng)速度為耦合方式，如果提供一個(gè)低的直流輸入電壓（≤7V）。每個(gè)速度從20到23 RPS不同。但這些速度高度都是受到頻率，如果提供一個(gè)較高的直流輸入電壓（≥8V）。例如，驅(qū)動(dòng)速度約等于驅(qū)動(dòng)速度的耦合方式低頻（≤73.0千赫）或高頻（≥78.5千赫）。每個(gè)速度仍是從20至23 RPS不同。值得注意的是，驅(qū)動(dòng)速度大大下降到零，并且行駛速度是略微達(dá)因換29 RPS在76.0千赫的頻率從耦合到非耦合模式，如果一個(gè)高的直流輸入電壓（≥11 V）被提供。因此，離合器機(jī)構(gòu)可以用于控制驅(qū)動(dòng)部的速度變化，如果壓電式蜂鳴器在驅(qū)動(dòng)或從驅(qū)動(dòng)構(gòu)件被電壓擊中，在不同電壓下壓電式蜂鳴器適用于76.0千赫附近的共振頻率的頻率。 關(guān)于驅(qū)動(dòng)速度的瞬態(tài)響應(yīng)，響應(yīng)時(shí)間（?= 1.5秒，如圖15（a））的條件下從所述非接觸式稍微接觸模式變化的速度超過(guò)（?= 0.9秒，如圖所示。圖15（b））的條件下從接觸到非接觸方式發(fā)生變化。從圖15（a）和（b）所示，非接觸模式的驅(qū)動(dòng)速度是零，并且，所述接觸模式的是在約22 RPS穩(wěn)定狀態(tài)時(shí)，離合器的蜂鳴器中的通電由驅(qū)動(dòng)電壓來(lái)驅(qū)動(dòng)（即VDC =12V），并且通過(guò)通電頻率（即F =76.0千赫）來(lái)測(cè)量驅(qū)動(dòng)速度間接和迷你直流電機(jī)的穩(wěn)定結(jié)果（TS10SA，東元電機(jī)股份有限公司，香港，中國(guó)）具備25mm長(zhǎng)度，20.1毫米寬度和高度15.1毫米播放發(fā)電或連接到一個(gè)沿對(duì)準(zhǔn)軸線與從動(dòng)軸的感測(cè)作用端部。為直流電動(dòng)機(jī)，規(guī)格的端電壓幾乎等于所產(chǎn)生的電壓，，如果直流馬達(dá)起著發(fā)電機(jī)的作用，該電壓是線性增加下加快作業(yè)轉(zhuǎn)速。同時(shí)，一端電壓之間的線性關(guān)系的斜率的旋轉(zhuǎn)速度是約6.8毫伏/ RPS。從測(cè)得的結(jié)果，150mV，在直流電動(dòng)機(jī)的端子電壓約表示22 RPS的離合器從動(dòng)速度。 圖16 摩擦?xí)r間響應(yīng)中的部件相面對(duì)的表面 基于上述結(jié)果，對(duì)摩擦?xí)r間的響應(yīng)結(jié)果，進(jìn)行了相對(duì)表面的討論。從圖16面對(duì)的表面彼此充分接觸，并且驅(qū)動(dòng)軸和從動(dòng)軸是靜止的點(diǎn)（一）如果在使用驅(qū)動(dòng)器的條件下，其公式為VM = Vdc = 0V。然后，在相對(duì)的表面仍然完全相互接觸，并且靜摩擦力，fs的，相面對(duì)的表面之間從零增大到最大靜摩擦力， FS ，最大，在路徑（二）驅(qū)動(dòng)器的條件，包括虛擬機(jī)≤ 3V和VDC = 0V ，使用。此外，相面對(duì)的表面是由點(diǎn)彼此接觸，并且最大靜摩擦力是下到動(dòng)摩擦，F(xiàn)K，在路徑（三）驅(qū)動(dòng)器的條件，包括VM = 3V和VDC ≤ 7V ，使用。此外，面對(duì)的表面不接觸彼此，并且動(dòng)摩擦幾乎是恒定的在之間的空間利用強(qiáng)大的超聲波懸浮面對(duì)表面的路徑（ IV ）如果驅(qū)動(dòng)條件，包括VM = 3V和伏≥ 8V。所示的臨界點(diǎn)在圖16的頂部表示的最大摩擦?xí)蚰Σ翜y(cè)量裝置或估計(jì)測(cè)試儀適用于找到堆焊靜態(tài)或動(dòng)態(tài)摩擦成員在今后的離合器機(jī)構(gòu)面。 7.結(jié)論 薄盤(pán)壓電式蜂鳴器成功地用作耦合方式中的摩擦元件或機(jī)械在驅(qū)動(dòng)或從動(dòng)件的耦合模式中振動(dòng)。如果必要，兩個(gè)構(gòu)件可以彼此互換。這里，驅(qū)動(dòng)部件被連接到一個(gè)驅(qū)動(dòng)馬達(dá)和所述驅(qū)動(dòng)構(gòu)件被連接到機(jī)械負(fù)載。從測(cè)量的結(jié)果中，在面向構(gòu)件的表面被緊緊地連接在一起，用于創(chuàng)建的耦合模式。如果所有壓電蜂鳴器沒(méi)有電氣由交流電力通電，這些面也相互分離。在制造非耦合模式下，如果一個(gè)或兩個(gè)壓電蜂鳴器完全由高AC功率電激勵(lì)。因此，根據(jù)非耦合模式驅(qū)動(dòng)軸來(lái)驅(qū)動(dòng)從動(dòng)軸的耦合模式下，驅(qū)動(dòng)部件仍然旋轉(zhuǎn)，從動(dòng)軸停止。 參考文獻(xiàn) [1] J.P. 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Seya, Consideration of sample dimension for ultrasonic levitation, in: Proc. IEEE Ultrason. Symp., vol. 3, 1990, pp.1271–1274. [20] J. Hu, K. Nakamura, S. Ueha, An analysis of a non-contact motor with an ultrasonically levitated rotor, Ultrasonics 35 (1997) 459–467. [21] B. Chu, R.E. Apfel, Acoustic radiation pressure produced by a beam of sound, J. Acoust. Soc. Am. 72 (1982) 1673–1687. [22] K.-T. Chang, M. Ouyang, Rotary ultrasonic motor driven by a diskshaped ultrasonic actuator, IEEE Trans. Ind. Electron. 53 (2006) 831–837. [23] P.V. O’Neil, Advanced Engineering Mathematics, Central Book Company, Taipei, 1983, p. 302. [24] T. Ikeda, Fundamentals of Piezoelectricity, Oxford University Press, New York, 1990. 傳記 Kuo-Tsai Changwas born in Taiwan, ROC, in 1964. He received theMSdegree from the Department of Electrical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan, ROC, in 1991, and received the PhD degree from the Department of Engineering and System Science, National Tsing Hua University, Hsinchu, Taiwan, ROC, in 1992. From 2002 to 2006, he was an associate professor in the Department of Electrical Engineering, National United University (NUU), Miaoli, Taiwan, ROC. Since 2006, he has been a professor in the Department of Electrical Engineering at the NUU. His research interests are in the areas of piezoelectric applications, ultrasonic motors and power electronics. Hsuang-Chang Chiang was born in Taiwan, ROC, in 1965. He received the BS and PhD degrees from the Department of Electrical Engineering, National Tsing Hua University, Hsinchu, Taiwan, ROC, in 1987 and 1994, respectively. From 1995 to 2001, he was an associate professor in the Department of Electrical Engineering, National United University (NUU), Miaoli, Taiwan, ROC. Since 2001, he has been a professor in the Department of Electrical Engineering at the NUU. His research interests are in the areas of power electronics, control systems and motor drives. Chun-Wei Lee was born in Taiwan, ROC, in 1982. He received the BS degree from the Department of Electrical Engineering, Ching Yun University, Chung Li, Taiwan, ROC, in 2005, and received the MS degree from the Department of Electrical Engineering, National United University, Miaoli, Taiwan, ROC, in 2007. His research interests are in the areas of control systems and piezoelectric applications. Available online at Sensors and Actuators A 141(2008)515522Design and implementation of a piezoelectric clutch mechanismusing piezoelectric buzzersKuo-Tsai Chang,Hsuang-Chang Chiang,Chun-Wei LeeDepartment of Electrical Engineering,National United University,1,Lien Da,Kungching Li,Miaoli 36003,Taiwan,ROCReceived 20 December 2006;received in revised form 10 July 2007;accepted 3 October 2007Available online 16 October 2007AbstractThis paper develops a novel piezoelectric clutch mechanism,including a driving member and a driven member,and investigates the clutchingperformance of the clutch mechanism.Each member is based on a thin-disk piezoelectric buzzer as a frictional member under coupling mode and amechanical vibrator under non-coupling mode.In doing so,the clutch mechanism and its experimental set-up namely a power transmission systemare first expressed.Then,operating principles such as inverse piezoelectric effect and ultrasonic levitation for separating two facing surfaces of themembers are stated,and a carbon-powder imaging method for observing the vibration mode of the piezoelectric buzzer is introduced.Moreover,a DC/AC resonant inverter for converting a DC source to a sinusoidal source applied to energize the piezoelectric buzzer is constructed.Finally,relationships between rotational speeds and electrical conditions as well as the transient response of the rotation speed with the condition of changeare investigated.2007 Elsevier B.V.All rights reserved.Keywords:Piezoelectric clutch;Piezoelectric buzzer;Vibration mode;Piezoelectric effect1.IntroductionConventional clutches,including electromagnetic clutches,gear clutches,friction clutches,overrunning clutches and cen-trifugalclutches,areusuallyappliedtostartorstopamechanicalload,and even to control a revolving speed of the mechanicalload in power transmission systems.For the electromagneticclutches,some magnetic powders with magnetic flux linkagesenclosed by an exciting coil are needed to transmit the torquefromthedrivingtodrivenendaftermagnetization.Thetransmit-ted torque is approximately proportional to the magnetic fieldor magnetization current.Each electromagnetic clutch is capa-ble of connecting the driving and driven members at the samespeedorundercontrollablespeeddifference.Unfortunately,anyelectromagnetic clutch has its inherent shortcoming such as agreat electromagnetic interference(EMI),which is unfavorableat free-of-EMI sites such as hospitals or precision laboratories,during the running of the clutch 14.Corresponding author.Tel.:+886 37 381372;fax:+886 37 327887.E-mail address:ktchangnuu.edu.tw(K.-T.Chang).For the gear clutches,protrusions such as gear teeth or keysare built in the driving and driven members.The differencebetween the driving and driven speeds is small in order to avoidan excessive impact or damaging the gear clutches under cou-pling and non-coupling modes 58.For the friction clutches,the driving and driven members are connected with each otherusing frictions,which enable the driving member to drive thedriven member indeed.They are promptly connected or sep-arated by a small impact force or a little vibration.However,an abrasive slip at the contact of the members is caused by aheavy load to shorten the durability of the clutching materialsor maintain the members frequently 911.For the overrun-ning clutches,an overrunning clutch comprises ratchet wheels,ratchet pawls,rotary cylinders and wedge blocks.This clutch isused to transmit the torque or motion from the driving to drivenend in one-way direction.In spite of its simple construction,a considerably bulky size and a loud noise arising at the tran-sientmomentofthemembersfromthecouplingtonon-couplingmode restrict this type of mechanism can only applicable forlow-speed and non-precision machines 12,13.For the centrifugal clutches,the contact of the driving anddriven members is automatically connected or separated by acentrifugal force if the desired speed at the driving or driven0924-4247/$see front matter 2007 Elsevier B.V.All rights reserved.doi:10.1016/j.sna.2007.10.018516K.-T.Chang et al./Sensors and Actuators A 141(2008)515522Fig.1.Piezoelectric clutch mechanism.end is arrived.But this clutch has a considerably bulky mecha-nism 14,15.To mitigate or solve the aforementioned problemsregarding the above conventional clutches,an ultrasonic clutchfor a driving power control of multi-fingered exoskeleton hapticdevice with passive force feedback control has been developed16.And,an ultrasonic clutch,including two ultrasonic trans-ducers as mechanical vibrators and frictional members as well,for controlling the contact or non-contact between the drivingand driven shafts has been investigated 17.These ultrasonicclutches are heavy and bulky.Based on the above,this paper develops a novelpiezoelectricclutchmechanism,includingtwothin-diskpiezoelectricbuzzersas mechanical vibrators and frictional members as well,to min-imize the clutch mechanism,cancel the EMI effect,decline theimpact of the members at the transient state from the couplingto non-coupling mode,and control the power transmitted fromthe driving to driven end.2.Mechanism designFrom Fig.1,the piezoelectric clutch mechanism containsa driving member and a driven member,each of which con-tains a thin-disk piezoelectric buzzer(TE41208-26,SeahornInc.,Taipei,Taiwan),a driving or driven shaft,a plastic fixer,aFig.2.Structure of piezoelectric buzzer.Fig.3.Electrical drive of piezoelectric buzzer.conductive tap and two electric wires.The piezoelectric buzzercomprises a piezoceramic disk(diameter,24.8mm;thickness,0.1mm),a nickel-alloy disk(diameter,41.0mm;thickness,0.1mm)and a silvering electrode(diameter,24.8mm;thick-ness,0.02mm),as shown in Fig.2.The piezoceramic disk has apolingdirectionatitsthicknessdirection.Themassofthepiezo-electric buzzer is approximately 1.5g.For the electrical drive,an electrical sinusoidal source is supplied to the piezoelectricbuzzer via the nickel-alloy disk and the silvering electrode,asdepicted in Fig.3.Intheassemblyoftheclutchmechanism,theconductivetapisadheredtotheoutsideoftheplasticfixer.Theaxisofthedrivingshaft is aligned that of the driven shaft.The piezoelectric buzzerisfixedtotheedgeoftheplasticfixerbyviscoseatanodalcircleof the vibration mode on the nickel-alloy disk.For the electricwires,one is mounted between the driving(driven)shaft andthe silvering electrode,and the other is mounted between theconductive tap and the nickel-alloy disk.Fig.4.Power transmission system.K.-T.Chang et al./Sensors and Actuators A 141(2008)515522517Fig.5.Inverse piezoelectric effect.Fig.6.Near-field acoustic levitation.From Fig.4,the power transmission system comprises theclutchmechanism,anelectricalcontrolsystem,twopreloadcon-trollers,two plastic couplings,and others.The electrical controlsystem includes an AC power supply system,two switches S1and S2,two conductive taps,four carbon brushes,and a sourcebase.This system is used to control electrical drive conditionsof the members and determine the coupling or non-couplingmode of the clutch mechanism.Each preload controller con-tains a stainless spring,two metal washers,and a linear bearing,where the washers are mounted at both ends of the spring,andthe bearing is needed to support and guide the driving or drivenshaft along a center line of the clutch mechanism.This con-troller provides a preload force to the driving or driven memberFig.7.Principle of carbon-powder imaging method:(a)movement of powders;(b)distribution of electrical charges.Fig.8.Patternsofvibrationmode:(a)front-viewpattern;(b)back-viewpattern.soastoensurethatfacingsurfacesofthemembersareconnectedwith each other under coupling mode.For specifications of thespring,the plastic coefficient is about 1.15g/cm,the length isapproximately18mm,andthediameterisapproximately4mm.Thus,the preload force on the contact of the facing surfacesis approximately 0.46g.In the connection of the plastic cou-plings,one is linked between the driving shaft and a motorshaft,and the other is linked between the driven shaft and aload shaft.3.Operating principleThe non-coupling mode of the clutch mechanism is basedon near-field acoustic levitation 1820,which is caused byinverse piezoelectric effect.For the inverse piezoelectric effect,518K.-T.Chang et al./Sensors and Actuators A 141(2008)515522Fig.9.Dimensional view of the front-view pattern.the shape of a piezoelectric element extends by a positiveDC driving voltage,and contracts by a negative DC driv-ing voltage,as shown in Fig.5.For the acoustic levitation,an object with a planar-and-rigid bottom suspends above aradiation surface of a piezoelectric vibrator using a radia-tion pressure (kgw/m2)on the bottom of the object,and apiston-like acoustic wave occurs in the space between the lev-itation object and the radiation surface,as depicted in Fig.6.Generally,the levitation height is much less than the wave-length of the acoustic wave.This height,h(m),is expressedbyh=a0?1+4ac2a(1)where a0is the vibration amplitude(m),ais the sound den-sity of medium(kg/m3),cais the sound velocity of medium(m/s),and is the specific heat ratio 21.Using Eq.(1),thelevitation height increases with the vibration amplitude if theparameters such as a,ca,and are constant.Additionally,the non-coupling mode of the clutch mechanism results largelyfromtheacousticlevitationsothatthedrivenshaftalmoststops,but the driving shaft still rotates.From Figs.1 and 4,the members are arranged to rotate abouta common axis of rotation to be in contact with each other in aFig.10.Schematic vibration mode.Fig.11.AC power supply system.Fig.12.Speed measuring system.first state if both piezoelectric buzzers in the members are elec-trically energized by low AC power.These members are furthermovedintoasecondstatewherebythedrivingmemberisdiscon-nectedfromthedrivenmemberusingastrongradiationpressurefield on the facing surface of the piezoelectric buzzer if one ortwo piezoelectric buzzers in the members are electrically ener-gizedbyhighACpower.Bothmembersmaybeinterchangeablewith one another,if necessary.Then,the contact surfaces of themembers are tightly coupled together without electrically ener-gizing the piezoelectric buzzers,so as to get the fact that thedriving member drives the driven member.These surfaces arealso separated for disconnecting the members,so as to stop thedriven member,but still rotate the driving member,if one ortwo piezoelectric buzzers are electrically energized by high ACpower.Fig.13.Speeds vs.DC input voltage at the frequency of 76.0kHz.K.-T.Chang et al./Sensors and Actuators A 141(2008)515522519Fig.14.Speeds vs.frequency under different voltages:(a)Vdc=1,2,3V;(b)Vdc=4,5,6V;(c)Vdc=7,8,9V;(d)Vdc=10,11,12V.4.Mechanical analysisAsreferringtoRef.22,thevibrationmodeoftheelectricallyenergized piezoelectric buzzer is observed by a carbon-powderimagingmethodsoastoelucidatethedisconnectionbetweenthefacingsurfacesofthemembers.Tooperatetheimagingmethod,some carbon powders are first uniformly spread on both sidesof the piezoelectric buzzer.Then,the powders are moving fromthe loops to nodes in the axialsymmetrical flexural vibration ofthe piezoelectric buzzer,as shown in Fig.7(a),until revealinga pattern of the vibration mode after electrically turning on.The pattern of the vibration mode still holds on both sides ofthe piezoelectric buzzer due to positive and negative chargescaused by a residual electric field Er,as shown in Fig.7(b),afterelectricallyturningoff.Moreover,patternsofthevibrationmodeat both sides of the piezoelectric buzzer are depicted in Fig.8(a)and(b)if the piezoelectric buzzer is electrically energized byan electrical sine source,involving the amplitude of 5V andthe frequency of 73.25kHz.In the patterns,dark areas indicatenodes of the vibration mode,and bright areas indicate loops ofthe vibration mode.From Fig.9,the diameter of the first nodalcircle,n1,is approximately 5.9mm,the diameter of the secondnodal circle,n2,is approximately 14.0mm,and the diameterof the third nodal circle,n3,is approximately 21.2mm.Next,a two-dimensional(2D)wave equation of a thin-diskpiezoelectric element such as a thin-disk piezoelectric buzzer isdefined as follows2u(r,t)=1c22t2u(r,t)(2)wherec=?THere,u is the vibration amplitude,r is the radius,and is thegeometrical angle;c is the sound velocity,T is the horizontaltension,and is the mass density.Thus,c is constant if T and areconstant.ThevariableisfurtherwithdrawnfromEq.(2)duetotheaxialsymmetricalmodeofthepiezoelectricbuzzer.Thus,the solution of the 2D wave equation contains a term of zero-order first-kind Bessel function J0and a term of Euler functionejtif the piezoelectric buzzer is electrically energized by an520K.-T.Chang et al./Sensors and Actuators A 141(2008)515522electrical sine source.This solution indicating the mechanicalvibration is expressed byu(r,t)=AmJ0(kr)ejt(3)wherek=2=cHere,Amis the vibration amplitude,k is the wave num-ber,is the wavelength,and is the angular frequency.Aschematic diagram of the vibration mode is revealed in Fig.10.Additionally,n1:n2:n3=01:02:03,calculatedby01=2.4,02=5.6,and03=8.6,where 01,02and 03are the first,second and third zeros of zero-order first-kind Bessel func-tion J0,respectively 23.This finding indicates that Eq.(3)is available for analyzing the vibration behavior of the piezo-ceramic part.Therefore,the axialsymmetry flexural vibrationmode almost dominates the vibration behavior of the piezoelec-tricbuzzerunderfreeboundaryconditionsbecausethediameter2greatly exceeds that of the thickness t2in the piezoceramicdisk 24.Also,2/t2=248,calculated by 9=24.8mm,andt2=0.1mm.5.Experimental setupAn AC power supply system for generating an electrical sinesource at input terminals of the piezoelectric buzzer is shownin Fig.11.This system includes a DC/AC resonant inverter,adriven and isolated circuit,a DC power supply(LPS305,Amer-ican Reliance Inc.,EI Monte,CA)and a function generator(FG506,American Reliance Inc.,EI Monte,CA).The resonanttank consists of a series inductance Lf(=64?H)and a parallelcapacitance Cf(=0.1?F).The resonant inverter contains a full-bridge chopper with four MOSFET devices(IRF840,UnitrodeInc.,Dallas,TX),a resonant tank and an equivalent circuit ofthe piezoelectric buzzer.The MOSFET devices are controlledby four rectangular triggering signals vgs1 vgs4,respectively,which are produced from the driven and isolated circuit andcontrolled by the function generator.A pulse width modulationsignal vpwmas an input signal of the driven and isolated circuitis generated from the function generator.Thus,the amplitudeof the sine source is controlled by the DC power supply,andthe frequency of the sine source is controlled by the functiongenerator.From Fig.12,a speed measuring system,includingtwo digital optical tachometers(RM-1501,Prova Inc.,Taipei,Taiwan)and two optical reflectors,is constructed to measurerotational speeds of the shafts in the members.Each reflector isadheredontheoutsideoftheplasticfixerinthedrivingordrivenmember.6.Results and discussionAccording to Fig.4,the piezoelectric buzzer in the drivenmemberiselectricallyenergizedbyelectricalsinesourcesatthesame frequency of 76.0kHz that is the resonance frequency ofthe piezoelectric buzzer using different voltages,which are con-trolledbytheDCpowersupplyshowninFig.11.TheamplitudeFig.15.Measured transient responses of the driven speed using Vdc=12V andf=76.0kHz under different conditions of changes:(a)from the non-contact tocontact modes;(b)from the contact to non-contact modes.of electrical sine source approximately increases with the DCinput voltage if the driving frequency is constant.From Fig.13,the driving speed indicating a speed of the driving shaft almostequals the driven speed indicating a speed of the driven shaftfor the coupling mode of the clutch mechanism if a low DCinput voltage(7V)is supplied.Each speed is varying from 20to 23rps.Here,rps means the revolution per second.Also,thedriving speed is up to 29rps,and the driven speed is down tozeroforthenon-couplingmodeoftheclutchmechanismifahighDC input voltage(8V)is supplied.Therefore,a function ofthe clutch mechanism from the coupling to non-coupling modeis enhanced by increasing the DC input voltage or the amplitudeof the sine source if the driving frequency is constant.Next,effects of driving frequencies on the speeds are stated.From Fig.14(a)(d),the driving and driven speeds are almostunaffected by driving frequencies from 70 to 80kHz,and thedrivingspeedisapproximatelyequivalenttothedrivenspeedforthe coupling mode if a low DC input voltage(7V)is supplied.Each speed is varying from 20 to 23rps.But these speeds arehighly affected by the frequencies if a high DC input voltageK.-T.Chang et al./Sensors and Actuators A 141(2008)515522521Fig.16.Friction time-response of the facing surfaces in the members.(8V)is supplied.For example,the driving speed approxi-mately equals the driven speed for the coupling mode at thelow frequencies(73.0kHz)or high frequencies(78.5kHz).Each speed is still varying from 20 to 23rps.Notably,the drivenspeed is greatly down to zero,and the driving speed is slightlyup to 29rps at the frequency of 76.0kHz due to the change fromthe coupling to non-coupling mode if a high DC input voltage(11V)is supplied.Therefore,the clutch mechanism can beused for speed variation in the driven part if the piezoelectricbuzzer in the driving or driven member is electrically energizedat the frequency of 76.0kHz near the resonant frequency of thepiezoelectric buzzer under different voltages.Regarding the transient response of the driven speed,theresponse time(=1.5s,as shown in Fig.15(a)under the condi-tion of change from the non-contact to contact modes slightlyexceeds that(=0.9s,as shown in Fig.15(b)under the condi-tion of change from the contact to non-contact modes.FromFig.15(a)and(b),the driven speed of the non-contact mode iszero,and that of the contact mode is approximately 22rps insteady state when one of the buzzers in the clutch is electricallyenergized by the driving voltage(i.e.Vdc=12V)and the opera-tion frequency(i.e.f=76.0kHz).To measure the transient andsteady results of the driven speed indirectly,a mini DC motor(TS10SA,Teco Electric Inc.,Hong Kong,China)with 25mmlength,20.1mm width and 15.1mm height for playing the gen-eratingorsensingroleisconnectedtotheendofthedrivenshaftalong an aligning axis.For specifications of the DC motor,theterminal voltage almost equals the generated voltage which islinearlyincreasedwithrotationalspeedunderopen-circuitoper-ations if the DC motor plays the generating role.Meanwhile,aslope of a linear relationship between the terminal voltage andtherotationalspeedisapproximately6.8mV/rps.Fromthemea-sured results,the terminal voltage of 150mV in the DC motorapproximately indicates the driven speed of 22rps in the clutch.Based on the above results,a friction time-response of thefacing surfaces of the members is discussed.From Fig.16,thefacing surfaces are fully contact with each other,and the drivinganddrivenshaftsarestaticatthepoint(I)ifthedriveconditions,including VM=Vdc=0V,are used.Then,the facing surfacesare still fully contact with each other,and the static friction,fs,between the facing surfaces is increased from zero to themaximum static friction,fs,max,at the path(II)if the drive con-ditions,including VM3V and Vdc=0V,are used.Moreover,the facing surfaces are contact with each other by points,andthe maximum static friction is down to the kinetic friction,fk,at the path(III)if the drive conditions,including VM=3V andVdc7V,areused.Furthermore,thefacingsurfacesarenotcon-tact with each other,and the kinetic friction is almost constantby using a strong ultrasonic levitation in the space between thefacing surfaces at the path(IV)if the drive conditions,includ-ing VM=3V and Vdc8V,are used.The critical point shownin the top of Fig.16 indicating the maximum friction will be522K.-T.Chang et al./Sensors and Actuators A 141(2008)515522measured or estimated by friction measuring devices or