壓(ya)(ya)力變送(song)器(qi)是工業實(shi)踐中常用(yong)(yong)的(de)(de)一(yi)種(zhong)(zhong)傳感器(qi)，其廣泛應用(yong)(yong)于(yu)各(ge)種(zhong)(zhong)工業自控環境(jing)，涉及水(shui)(shui)利(li)水(shui)(shui)電(dian)、鐵路(lu)交通(tong)、智能建筑、生產自控、航(hang)空航(hang)天、軍(jun)工、石(shi)化(hua)、油井、電(dian)力、船舶、機床、管道等眾多行業。下面(mian)就簡單介(jie)紹一(yi)些常用(yong)(yong)壓(ya)(ya)力變送(song)器(qi)的(de)(de)原(yuan)理及其應用(yong)(yong)、壓(ya)(ya)力變送(song)器(qi)是用(yong)(yong)于(yu)測(ce)量液體、氣(qi)體或蒸汽的(de)(de)液位、密度和壓(ya)(ya)力，然后(hou)將壓(ya)(ya)力信號轉(zhuan)變成(cheng)4～20mA DC信號輸出。
壓(ya)(ya)(ya)(ya)力(li)(li)變(bian)(bian)(bian)(bian)送(song)(song)(song)(song)器主要(yao)有電(dian)容(rong)式壓(ya)(ya)(ya)(ya)力(li)(li)變(bian)(bian)(bian)(bian)送(song)(song)(song)(song)器和擴散硅壓(ya)(ya)(ya)(ya)力(li)(li)變(bian)(bian)(bian)(bian)送(song)(song)(song)(song)器，陶瓷(ci)壓(ya)(ya)(ya)(ya)力(li)(li)變(bian)(bian)(bian)(bian)送(song)(song)(song)(song)器，應(ying)變(bian)(bian)(bian)(bian)式壓(ya)(ya)(ya)(ya)力(li)(li)變(bian)(bian)(bian)(bian)送(song)(song)(song)(song)器等。壓(ya)(ya)(ya)(ya)力(li)(li)變(bian)(bian)(bian)(bian)送(song)(song)(song)(song)器根據測壓(ya)(ya)(ya)(ya)范圍可分成一般壓(ya)(ya)(ya)(ya)力(li)(li)變(bian)(bian)(bian)(bian)送(song)(song)(song)(song)器（0.001MPa～35MPa）和微差壓(ya)(ya)(ya)(ya)變(bian)(bian)(bian)(bian)送(song)(song)(song)(song)器（0～1.5kPa），負壓(ya)(ya)(ya)(ya)變(bian)(bian)(bian)(bian)送(song)(song)(song)(song)器三種。
壓(ya)(ya)力(li)(li)變送(song)器(qi)的(de)主要作用把(ba)壓(ya)(ya)力(li)(li)信(xin)號(hao)傳到電(dian)(dian)(dian)(dian)(dian)子設備(bei)，進(jin)而在計算機顯示(shi)壓(ya)(ya)力(li)(li)其原理大致是(shi)：將水(shui)壓(ya)(ya)這(zhe)種壓(ya)(ya)力(li)(li)的(de)力(li)(li)學信(xin)號(hao)轉變成電(dian)(dian)(dian)(dian)(dian)流（4-20mA）這(zhe)樣的(de)電(dian)(dian)(dian)(dian)(dian)子信(xin)號(hao)壓(ya)(ya)力(li)(li)和電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)或(huo)電(dian)(dian)(dian)(dian)(dian)流大小成線性關系(xi)，一般是(shi)正比(bi)關系(xi)。所以，變送(song)器(qi)輸出(chu)(chu)的(de)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)或(huo)電(dian)(dian)(dian)(dian)(dian)流隨壓(ya)(ya)力(li)(li)增大而增大由此得出(chu)(chu)一個壓(ya)(ya)力(li)(li)和電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)或(huo)電(dian)(dian)(dian)(dian)(dian)流的(de)關系(xi)式壓(ya)(ya)力(li)(li)變送(song)器(qi)的(de)被測介質(zhi)的(de)兩種壓(ya)(ya)力(li)(li)通入高、低(di)兩壓(ya)(ya)力(li)(li)室，低(di)壓(ya)(ya)室壓(ya)(ya)力(li)(li)采用大氣壓(ya)(ya)或(huo)真空，作用在δ元(yuan)（即敏(min)感元(yuan)件(jian)）的(de)兩側隔離膜片(pian)上(shang)，通過隔離片(pian)和元(yuan)件(jian)內(nei)的(de)填充液傳送(song)到測量膜片(pian)兩側。
壓力(li)變送(song)器(qi)是由測(ce)量(liang)膜片(pian)與兩(liang)(liang)側絕緣片(pian)上的電極各組成(cheng)一個電容(rong)器(qi)。當兩(liang)(liang)側壓力(li)不一致(zhi)(zhi)時，致(zhi)(zhi)使測(ce)量(liang)膜片(pian)產生位移，其位移量(liang)和(he)壓力(li)差成(cheng)正(zheng)比，故兩(liang)(liang)側電容(rong)量(liang)就不等，通過振蕩和(he)解調環節。
