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液壓電磁比例調節閥工作原理及常見故障

時間(jian): 2020-12-14瀏覽: 0

液(ye)壓(ya)電(dian)磁(ci)比(bi)例(li)(li)調節(jie)閥分為壓(ya)力比(bi)例(li)(li)調節(jie)閥和流量比(bi)例(li)(li)調節(jie)閥(控制(zhi)(zhi)原(yuan)理基本相同(tong)),常(chang)應(ying)用在控制(zhi)(zhi)精(jing)度較(jiao)高的(de)(de)液(ye)壓(ya)系(xi)統。比(bi)例(li)(li)調節(jie)閥正常(chang)使(shi)用8000~12 000h后(hou),即進人工作不(bu)穩定(ding)期,經(jing)常(chang)出現(xian)油路(lu)壓(ya)力不(bu)穩、動(dong)作不(bu)到(dao)位、調節(jie)功能失效等現(xian)象,嚴重影響設(she)備運(yun)行。下面(mian)以某公司使(shi)用的(de)(de)WRE型系(xi)列液(ye)壓(ya)電(dian)磁(ci)比(bi)例(li)(li)調節(jie)閥為例(li)(li),介紹常(chang)見(jian)故障處理方法。

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工作原(yuan)理

WRE型液(ye)壓電(dian)磁比例調節閥(fa)結(jie)構如圖16所示,采用(yong)(yong)位(wei)置負反(fan)饋閉環控(kong)(kong)(kong)制(zhi)(zhi)(力(li)控(kong)(kong)(kong)制(zhi)(zhi)型十位(wei)移傳感(gan)器(qi)),具有(you)良好的輸(shu)入、輸(shu)出(chu)線(xian)性和準確(que)性,控(kong)(kong)(kong)制(zhi)(zhi)原理(li)如圖17所示。位(wei)移傳感(gan)器(qi)反(fan)饋信(xin)(xin)號(hao)和給(gei)定(ding)(ding)信(xin)(xin)號(hao)合(he)成(cheng)(cheng)后,經過PID、放大(da)等運(yun)算處(chu)理(li),以電(dian)壓信(xin)(xin)號(hao)施加在電(dian)機(ji)械轉(zhuan)換器(qi)(電(dian)磁閥(fa)線(xian)圈),鐵心(xin)(xin)在電(dian)磁力(li)作用(yong)(yong)下(xia),沿著受(shou)力(li)方向推動(dong)液(ye)體(ti),控(kong)(kong)(kong)制(zhi)(zhi)閥(fa)心(xin)(xin)移動(dong),調節液(ye)體(ti)流量或(huo)壓力(li)。控(kong)(kong)(kong)制(zhi)(zhi)板(ban)是(shi)驅動(dong)比例調節閥(fa)的主要元器(qi)件,一般具有(you)控(kong)(kong)(kong)制(zhi)(zhi)信(xin)(xin)號(hao)生成(cheng)(cheng)、PID處(chu)理(li)、前置放大(da)、功率放大(da)及電(dian)源(yuan)變換等基本控(kong)(kong)(kong)制(zhi)(zhi)單元,完成(cheng)(cheng)控(kong)(kong)(kong)制(zhi)(zhi)信(xin)(xin)號(hao)給(gei)定(ding)(ding)、反(fan)饋信(xin)(xin)號(hao)校正、合(he)成(cheng)(cheng)和處(chu)理(li)等功能,控(kong)(kong)(kong)制(zhi)(zhi)板(ban)控(kong)(kong)(kong)制(zhi)(zhi)參數設(she)定(ding)(ding)是(shi)否(fou)匹配(pei)、適當(dang),直接(jie)影(ying)響液(ye)壓調節閥(fa)的工(gong)作和穩定(ding)(ding)性。


常見故障及(ji)處(chu)理方法

設備更換(huan)(huan)比例調節(jie)(jie)閽閥(fa)(fa)(fa)體后(hou),動(dong)(dong)作(zuo)(zuo)失(shi)控,邏輯關(guan)系錯(cuo)亂。拋丸清理機更換(huan)(huan)閥(fa)(fa)(fa)體起動(dong)(dong)后(hou),轉臺(液壓(ya)(ya)馬達驅動(dong)(dong))動(dong)(dong)作(zuo)(zuo)失(shi)控、互(hu)鎖邏輯關(guan)系錯(cuo)亂。當初認為是控制(zhi)(zhi)(zhi)板故(gu)(gu)障或更換(huan)(huan)的閥(fa)(fa)(fa)體不良,再(zai)次(ci)更換(huan)(huan),故(gu)(gu)障依舊。測量(liang)控制(zhi)(zhi)(zhi)板輸(shu)(shu)(shu)出(chu)電(dian)壓(ya)(ya)為U2c-32c或U2a-32a,帶負(fu)(fu)載時(shi)(shi)(shi)(接(jie)(jie)人(ren)電(dian)磁閥(fa)(fa)(fa)線(xian)圈)電(dian)壓(ya)(ya)為DC 21.5V、AC 2.2V;空載時(shi)(shi)(shi)為DC 24V、AC2.4V。對控制(zhi)(zhi)(zhi)電(dian)源復位(wei)(斷(duan)電(dian)送電(dian)操作(zuo)(zuo)),控制(zhi)(zhi)(zhi)板輸(shu)(shu)(shu)出(chu)電(dian)壓(ya)(ya)為零,只有輸(shu)(shu)(shu)入信(xin)號(hao)作(zuo)(zuo)用后(hou),輸(shu)(shu)(shu)出(chu)端才有電(dian)壓(ya)(ya)且保(bao)持不變(正常時(shi)(shi)(shi)輸(shu)(shu)(shu)入和(he)輸(shu)(shu)(shu)出(chu)同時(shi)(shi)(shi)得電(dian)或斷(duan)電(dian))。分析比例調節(jie)(jie)閥(fa)(fa)(fa)控制(zhi)(zhi)(zhi)原理,特別是位(wei)移(yi)傳感(gan)器(qi)工作(zuo)(zuo)過(guo)程,認為調節(jie)(jie)閥(fa)(fa)(fa)控制(zhi)(zhi)(zhi)系統此時(shi)(shi)(shi)實際工作(zuo)(zuo)在閉(bi)環(huan)正反饋狀(zhuang)態。檢查反饋電(dian)路,發(fa)現位(wei)移(yi)傳感(gan)器(qi)信(xin)號(hao)線(xian)8c、10c線(xian)接(jie)(jie)錯(cuo),造(zao)成二次(ci)線(xian)圈輸(shu)(shu)(shu)出(chu)信(xin)號(hao)極性錯(cuo)誤(wu),經信(xin)號(hao)轉換(huan)(huan),極性相(xiang)反,即圖17中極性變為負(fu)(fu),經負(fu)(fu)反饋合成,系統工作(zuo)(zuo)在閉(bi)環(huan)正反饋狀(zhuang)態。在輸(shu)(shu)(shu)入信(xin)號(hao)作(zuo)(zuo)用下(xia),控制(zhi)(zhi)(zhi)系統迅速進入自(zi)激深飽和(he)狀(zhuang)態,使控制(zhi)(zhi)(zhi)板輸(shu)(shu)(shu)出(chu)飽和(he)(DC 24V)。改正錯(cuo)誤(wu)接(jie)(jie)線(xian),故(gu)(gu)障排(pai)除。

液(ye)壓系統(tong)工作(zuo)時,設備(bei)(bei)運(yun)行(xing)速(su)度(du)不穩(wen)定。一期成型機轉臺(tai)運(yun)行(xing)速(su)度(du)忽高忽低(di),當初認(ren)為(wei)壓力調節閥(fa)體損壞或控制板輸出不穩(wen)定,導致液(ye)壓驅(qu)動(dong)馬(ma)達工作(zuo)異常,更(geng)換閥(fa)體后故障消失,但使用(yong)3天左右,同(tong)樣(yang)故障又偶爾出現,更(geng)換控制板,故障依舊。懷疑(yi)液(ye)壓油臟,進行(xing)成型機液(ye)壓油全部(bu)過(guo)濾,油箱清洗和過(guo)濾網(wang)更(geng)換等(deng)維(wei)護處理,設備(bei)(bei)投運(yun)后,故障消失。

設備長期使用,由于工作(zuo)環境(jing)惡(e)劣以及維修作(zuo)業(ye),液壓油(you)中會混入雜質(zhi)而變臟,造成液壓調節閥心(xin)運動阻塞或喘動,引起(qi)液壓驅動機構工作(zuo)不穩定。

設備(bei)操作(zuo)時,控(kong)制按(an)鈕(niu)動(dong)(dong)(dong)作(zuo)后(hou),液(ye)壓(ya)驅動(dong)(dong)(dong)機(ji)構反應遲緩,組裝拋丸清(qing)理(li)機(ji)更換比例調節閥(fa)控(kong)制板后(hou),液(ye)壓(ya)驅動(dong)(dong)(dong)轉(zhuan)臺(tai)機(ji)構從高位(wei)向(xiang)低位(wei)旋轉(zhuan)時,斷開(kai)控(kong)制按(an)鈕(niu)后(hou),轉(zhuan)臺(tai)旋轉(zhuan)到位(wei)后(hou)繼續移動(dong)(dong)(dong)約0.8~1.2m才停下(正常(chang)時轉(zhuan)臺(tai)到位(wei)后(hou)應立(li)即停止(zhi))。

通過比(bi)較設備故障(zhang)前后(hou)控(kong)制參數(shu),確認故障(zhang)原因是控(kong)制板信號PID處理參數(shu)調整(zheng)不當,控(kong)制板斜坡(po)控(kong)制電(dian)阻、d3、d4凼值調整(zheng)過小(xiao),導致控(kong)制板t4。(輸出電(dian)壓(ya)從DC 0升至24V所需時間)、t(輸出電(dian)壓(ya)從DC 24V降至0所需時間)設定過長,造成比(bi)例閥心回零滯后(hou),不能及時關閉(bi)液壓(ya)油。

在液(ye)壓比例調(diao)節閥(fa)控制(zhi)(zhi)的設備中,引起設備執(zhi)行機構工(gong)作異常(chang)(不(bu)到位(wei)、越位(wei)或失靈(ling)等)的原因較多(duo),諸如(ru)調(diao)節閥(fa)心磨損過(guo)度,高(gao)、低速驅動區(qu)調(diao)整不(bu)當,液(ye)壓系統內卸嚴重(zhong)以(yi)及控制(zhi)(zhi)參數(shu)設定(ding)不(bu)合適等。

液(ye)(ye)壓(ya)缸前(qian)進后退時移動(dong)速(su)度時間(jian)相(xiang)差較大。組裝磷鐵(tie)環壓(ya)脫(tuo)機主(zhu)(zhu)(zhu)缸頂(ding)出動(dong)作(zuo)(zuo)(zuo)時間(jian)過長,為(wei)23s,偏差約16s。當初認為(wei)是(shi)設備(bei)(bei)控(kong)(kong)制(zhi)電(dian)磁閥(fa)閥(fa)體(ti)油(you)(you)路阻塞(sai),進行解體(ti)、清洗閥(fa)體(ti),液(ye)(ye)壓(ya)油(you)(you)過濾等處理,故(gu)(gu)(gu)障(zhang)未明顯改善(shan)。考(kao)慮到主(zhu)(zhu)(zhu)缸沖(chong)葉閥(fa)內(nei)泄嚴重(zhong)也會出現該現象,于是(shi)整體(ti)更換沖(chong)葉閥(fa),故(gu)(gu)(gu)障(zhang)依舊。經(jing)了解,設備(bei)(bei)故(gu)(gu)(gu)障(zhang)前(qian)曾更換過設備(bei)(bei)液(ye)(ye)壓(ya)油(you)(you)、夾具及主(zhu)(zhu)(zhu)缸液(ye)(ye)壓(ya)控(kong)(kong)制(zhi)流(liu)量(liang)比(bi)例調(diao)節(jie)(jie)閥(fa)控(kong)(kong)制(zhi)板等維修作(zuo)(zuo)(zuo)業,雖然更換控(kong)(kong)制(zhi)板后,對其(qi)有關參數(shu)進行了調(diao)試整定(ding),但這是(shi)在設備(bei)(bei)空載(無導桿壓(ya)脫(tuo))情況下進行的(de)參數(shu)調(diao)整。判斷是(shi)流(liu)量(liang)比(bi)例調(diao)節(jie)(jie)閥(fa)零點(dian)調(diao)整不(bu)準(zhun)確(que),導致液(ye)(ye)壓(ya)油(you)(you)缸頂(ding)出油(you)(you)路供油(you)(you)流(liu)量(liang)變小,造成油(you)(you)缸頂(ding)出動(dong)作(zuo)(zuo)(zuo)時間(jian)過長。重(zhong)新整定(ding)控(kong)(kong)制(zhi)板參數(shu),校(xiao)正液(ye)(ye)壓(ya)流(liu)量(liang)調(diao)節(jie)(jie)閥(fa)零點(dian),帶負載工作(zuo)(zuo)(zuo)時,主(zhu)(zhu)(zhu)缸頂(ding)出動(dong)作(zuo)(zuo)(zuo)時間(jian)明顯減(jian)小,約為(wei)8s。

雖然更(geng)(geng)換(huan)的(de)控(kong)制(zhi)(zhi)板(ban)型號相同,但新、舊板(ban)電(dian)子元器(qi)件參(can)數(shu)存在(zai)差異,控(kong)制(zhi)(zhi)板(ban)處理(li)信(xin)(xin)號能(neng)力發生(sheng)了微(wei)小(xiao)變化(這也是電(dian)氣控(kong)制(zhi)(zhi)裝置(zhi)更(geng)(geng)換(huan)或維修(xiu)后(hou)需調試的(de)原因)。新板(ban)反饋信(xin)(xin)號轉(zhuan)換(huan)級(ji)零(ling)點偏移(yi)(yi),即當閥心(xin)在(zai)零(ling)位時,控(kong)制(zhi)(zhi)板(ban)上匹配放大器(qi)的(de)輸出(chu)(chu)(chu)不為零(ling),造成位移(yi)(yi)反饋信(xin)(xin)號大小(xiao)和閥心(xin)實(shi)際(ji)位移(yi)(yi)出(chu)(chu)(chu)現偏差,合成后(hou)的(de)控(kong)制(zhi)(zhi)信(xin)(xin)號值(zhi)發生(sheng)變化,液(ye)壓(ya)缸(gang)(gang)頂出(chu)(chu)(chu)驅動端輸出(chu)(chu)(chu)信(xin)(xin)號電(dian)壓(ya)較(jiao)低,作(zuo)(zuo)用在(zai)比例閥心(xin)上的(de)電(dian)磁(ci)力矩減小(xiao),導致液(ye)壓(ya)缸(gang)(gang)頂出(chu)(chu)(chu)動作(zuo)(zuo)時閥心(xin)位移(yi)(yi)較(jiao)小(xiao),給(gei)油量減小(xiao),造成主缸(gang)(gang)頂出(chu)(chu)(chu)動作(zuo)(zuo)緩(huan)慢,特別是重載時,動作(zuo)(zuo)更(geng)(geng)加(jia)遲(chi)緩(huan)。


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