Screw pump/SNS440R40U12.1W3板式螺桿油泵

Screw pump/SNS440R40U12.1W3板式螺桿油泵 SNH440R40U8W2 SNH440R46U8W2 SNH440R52U8W2 SNH440R54U8W2 SNF440R40U8W2 SNF440R46U8W2 SNF440R52U8W2 SNF440R54U8W2 SNS440R40U8W2 SNS440R46U8W2 SNS440R52U8W2 SNS440R54U8W2 SNH440R40U8W3 SNH440R46U8W3 SNH440R52U8W3 SNH440R54U8W3 SNF440R40U8W3 SNF440R46U8W3 SNF440R52U8W3 SNF440R54U8W3 SNS440R40U8W3 SNS440R46U8W3 SNS440R52U8W3 SNS440R54U8W3 SNH440R40U8W21 SNH440R46U8W21 SNH440R52U8W21 SNH440R54U8W21 SNF440R40U8W21 SNF440R46U8W21 SNF440R52U8W21 SNF440R54U8W21 SNS440R40U8W21 SNS440R46U8W21 SNS440R52U8W21 SNS440R54U8W21 SNH440R40U8W23 SNH440R46U8W23 SNH440R52U8W23 SNH440R54U8W23 SNF440R40U8W23 SNF440R46U8W23 SNF440R52U8W23 SNF440R54U8W23 SNS440R40U8W23 SNS440R46U8W23 SNS440R52U8W23 SNS440R54U8W23 SNH440R40U12.1W2 SNH440R46U12.1W2 SNH440R52U12.1W2 SNH440R54U12.1W2 SNF440R40U12.1W2 SNF440R46U12.1W2 SNF440R52U12.1W2 SNF440R54U12.1W2 SNS440R40U12.1W2 SNS440R46U12.1W2 SNS440R52U12.1W2 SNS440R54U12.1W2 SNH440R40U12.1W3 SNH440R46U12.1W3 SNH440R52U12.1W3 SNH440R54U12.1W3 SNF440R40U12.1W3 SNF440R46U12.1W3 SNF440R52U12.1W3 SNF440R54U12.1W3 SNS440R40U12.1W3 SNS440R46U12.1W3 SNS440R52U12.1W3 SNS440R54U12.1W3 SNH440R40U12.1W21 SNH440R46U12.1W21 SNH440R52U12.1W21 SNH440R54U12.1W21 SNF440R40U12.1W21 SNF440R46U12.1W21 SNF440R52U12.1W21 SNF440R54U12.1W21 SNS440R40U12.1W21 SNS440R46U12.1W21 SNS440R52U12.1W21 SNS440R54U12.1W21 SNH440R40U12.1W23 SNH440R46U12.1W23 SNH440R52U12.1W23 SNH440R54U12.1W23 SNF440R40U12.1W23 SNF440R46U12.1W23 SNF440R52U12.1W23 SNF440R54U12.1W23 SNS440R40U12.1W23 SNS440R46U12.1W23 SNS440R52U12.1W23 SNS440R54U12.1W23 SNH440R40E6.7W2 SNH440R46E6.7W2 SNH440R52E6.7W2 SNH440R54E6.7W2 SNF440R40E6.7W2 SNF440R46E6.7W2 SNF440R52E6.7W2 SNF440R54E6.7W2 SNS440R40E6.7W2 SNS440R46E6.7W2 SNS440R52E6.7W2 SNS440R54E6.7W2 SNH440R40E6.7W3 SNH440R46E6.7W3 SNH440R52E6.7W3 SNH440R54E6.7W3 SNF440R40E6.7W3 SNF440R46E6.7W3 SNF440R52E6.7W3 SNF440R54E6.7W3 SNS440R40E6.7W3 SNS440R46E6.7W3 SNS440R52E6.7W3 SNS440R54E6.7W3 SNH440R40E6.7W21 SNH440R46E6.7W21 SNH440R52E6.7W21 SNH440R54E6.7W21 SNF440R40E6.7W21 SNF440R46E6.7W21 SNF440R52E6.7W21 SNF440R54E6.7W21 SNS440R40E6.7W21 SNS440R46E6.7W21 SNS440R52E6.7W21 SNS440R54E6.7W21 SNH440R40E6.7W23 SNH440R46E6.7W23 SNH440R52E6.7W23 SNH440R54E6.7W23 SNF440R40E6.7W23 SNF440R46E6.7W23 SNF440R52E6.7W23 SNF440R54E6.7W23 SNS440R40E6.7W23 SNS440R46E6.7W23 SNS440R52E6.7W23 SNS440R54E6.7W23 TRSNH440-36 TRSNH440-40 TRSNH440-42 TRSNH440-46 TRSNH440-51 TRSNH440-54 TRSNF440-36 TRSNF440-40 TRSNF440-42 TRSNF440-46 TRSNF440-51 TRSNF440-54 TRSNS440-36 TRSNS440-40 TRSNS440-42 TRSNS440-46 TRSNS440-51 TRSNS440-54 TRSND440-36 TRSND440-40 TRSND440-42 TRSND440-46 TRSND440-51 TRSND440-54 TRSNK440-36 TRSNK440-40 TRSNK440-42 TRSNK440-46 TRSNK440-51 TRSNK440-54 HTSNH440-36 HTSNH440-40 HTSNH440-42 HTSNH440-46 HTSNH440-51 HTSNH440-54 HTSNF440-36 HTSNF440-40 HTSNF440-42 HTSNF440-46 HTSNF440-51 HTSNF440-54 HTSNS440-36 HTSNS440-40 HTSNS440-42 HTSNS440-46 HTSNS440-51 HTSNS440-54 HTSND440-36 HTSND440-40 HTSND440-42 HTSND440-46 HTSND440-51 HTSND440-54 HTSNK440-36 HTSNK440-40 HTSNK440-42 HTSNK440-46 HTSNK440-51 HTSNK440-54 HSNH440-36Z HSNH440-40Z HSNH440-42Z HSNH440-46Z HSNH440-51Z HSNH440-54Z HSNF440-36Z HSNF440-40Z HSNF440-42Z HSNF440-46Z HSNF440-51Z HSNF440-54Z HSNS440-36Z HSNS440-40Z HSNS440-42Z HSNS440-46Z HSNS440-51Z HSNS440-54Z HSNH440-36NZ HSNH440-40NZ HSNH440-42NZ HSNH440-46NZ HSNH440-51NZ HSNH440-54NZ HSNF440-36NZ HSNF440-40NZ HSNF440-42NZ HSNF440-46NZ HSNF440-51NZ HSNF440-54NZ HSNS440-36NZ HSNS440-40NZ HSNS440-42NZ HSNS440-46NZ HSNS440-51NZ HSNS440-54NZ HSNH440-36W1Z HSNH440-40W1Z HSNH440-42W1Z HSNH440-46W1Z HSNH440-51W1Z HSNH440-54W1Z HSNF440-36W1Z HSNF440-40W1Z HSNF440-42W1Z HSNF440-46W1Z HSNF440-51W1Z HSNF440-54W1Z HSNS440-36W1Z HSNS440-40W1Z HSNS440-42W1Z HSNS440-46W1Z HSNS440-51W1Z HSNS440-54W1Z HSNH440-36W1 HSNH440-40W1 HSNH440-42W1 HSNH440-46W1 HSNH440-51W1 HSNH440-54W1 HSNF440-36W1 HSNF440-40W1 HSNF440-42W1 HSNF440-46W1 HSNF440-51W1 HSNF440-54W1 HSNS440-36W1 HSNS440-40W1 HSNS440-42W1 HSNS440-46W1 HSNS440-51W1 HSNS440-54W1 HSNH440-36N HSNH440-40N HSNH440-42N HSNH440-46N HSNH440-51N HSNH440-54N HSNF440-36N HSNF440-40N HSNF440-42N HSNF440-46N HSNF440-51N HSNF440-54N HSNS440-36N HSNS440-40N HSNS440-42N HSNS440-46N HSNS440-51N HSNS440-54N HSNH440-36 HSNH440-40 HSNH440-42 HSNH440-46 HSNH440-51 HSNH440-54 HSNF440-36 HSNF440-40 HSNF440-42 HSNF440-46 HSNF440-51 HSNF440-54 HSNS440-36 HSNS440-40 HSNS440-42 HSNS440-46 HSNS440-51 HSNS440-54 HSND440-36W1 HSND440-40W1 HSND440-42W1 HSND440-46W1 HSND440-51W1 HSND440-54W1 HSND440-36N HSND440-40N HSND440-42N HSND440-46N HSND440-51N HSND440-54N HSND440-36 HSND440-40 HSND440-42 HSND440-46 HSND440-51 HSND440-54 HSNK440-36W1 HSNK440-40W1 HSNK440-42W1 HSNK440-46W1 HSNK440-51W1 HSNK440-54W1 HSNK440-36N HSNK440-40N HSNK440-42N HSNK440-46N HSNK440-51N HSNK440-54N HSNK440-36 HSNK440-40 HSNK440-42 HSNK440-46 HSNK440-51 HSNK440-54 HSNH440-36A HSNH440-40A HSNH440-42A HSNH440-46A HSNH440-51A HSNH440-54A HSNH440-36ZA HSNH440-40ZA HSNH440-42ZA HSNH440-46ZA HSNH440-51ZA HSNH440-54ZA SNH440R40U8W2 SNH440R46U8W2 SNH440R52U8W2 SNH440R54U8W2 SNF440R40U8W2 SNF440R46U8W2 SNF440R52U8W2 SNF440R54U8W2 SNS440R40U8W2 SNS440R46U8W2 SNS440R52U8W2 SNS440R54U8W2 SNH440R40U8W3 SNH440R46U8W3 SNH440R52U8W3 SNH440R54U8W3 SNF440R40U8W3 SNF440R46U8W3 SNF440R52U8W3 SNF440R54U8W3 SNS440R40U8W3 SNS440R46U8W3 SNS440R52U8W3 SNS440R54U8W3 SNH440R40U8W21 SNH440R46U8W21 SNH440R52U8W21 SNH440R54U8W21 SNF440R40U8W21 SNF440R46U8W21 SNF440R52U8W21 SNF440R54U8W21 SNS440R40U8W21 SNS440R46U8W21 SNS440R52U8W21 SNS440R54U8W21 SNH440R40U8W23 SNH440R46U8W23 SNH440R52U8W23 SNH440R54U8W23 SNF440R40U8W23 SNF440R46U8W23 SNF440R52U8W23 SNF440R54U8W23 SNS440R40U8W23 SNS440R46U8W23 SNS440R52U8W23 SNS440R54U8W23 SNH440R40U12.1W2 SNH440R46U12.1W2 SNH440R52U12.1W2 SNH440R54U12.1W2 SNF440R40U12.1W2 SNF440R46U12.1W2 SNF440R52U12.1W2 SNF440R54U12.1W2 SNS440R40U12.1W2 SNS440R46U12.1W2 SNS440R52U12.1W2 SNS440R54U12.1W2 SNH440R40U12.1W3 SNH440R46U12.1W3 SNH440R52U12.1W3 SNH440R54U12.1W3 SNF440R40U12.1W3 SNF440R46U12.1W3 SNF440R52U12.1W3 SNF440R54U12.1W3 SNS440R40U12.1W3 SNS440R46U12.1W3 SNS440R52U12.1W3 SNS440R54U12.1W3 SNH440R40U12.1W21 SNH440R46U12.1W21 SNH440R52U12.1W21 SNH440R54U12.1W21 SNF440R40U12.1W21 SNF440R46U12.1W21 SNF440R52U12.1W21 SNF440R54U12.1W21 SNS440R40U12.1W21 SNS440R46U12.1W21 SNS440R52U12.1W21 SNS440R54U12.1W21 SNH440R40U12.1W23 SNH440R46U12.1W23 SNH440R52U12.1W23 SNH440R54U12.1W23 SNF440R40U12.1W23 SNF440R46U12.1W23 SNF440R52U12.1W23 SNF440R54U12.1W23 SNS440R40U12.1W23 SNS440R46U12.1W23 SNS440R52U12.1W23 SNS440R54U12.1W23 SNH440R40E6.7W2 SNH440R46E6.7W2 SNH440R52E6.7W2 SNH440R54E6.7W2 SNF440R40E6.7W2 SNF440R46E6.7W2 SNF440R52E6.7W2 SNF440R54E6.7W2 SNS440R40E6.7W2 SNS440R46E6.7W2 SNS440R52E6.7W2 SNS440R54E6.7W2 SNH440R40E6.7W3 SNH440R46E6.7W3 SNH440R52E6.7W3 SNH440R54E6.7W3 SNF440R40E6.7W3 SNF440R46E6.7W3 SNF440R52E6.7W3 SNF440R54E6.7W3 SNS440R40E6.7W3 SNS440R46E6.7W3 SNS440R52E6.7W3 SNS440R54E6.7W3 SNH440R40E6.7W21 SNH440R46E6.7W21 SNH440R52E6.7W21 SNH440R54E6.7W21 SNF440R40E6.7W21 SNF440R46E6.7W21 SNF440R52E6.7W21 SNF440R54E6.7W21 SNS440R40E6.7W21 SNS440R46E6.7W21 SNS440R52E6.7W21 SNS440R54E6.7W21 SNH440R40E6.7W23 SNH440R46E6.7W23 SNH440R52E6.7W23 SNH440R54E6.7W23 SNF440R40E6.7W23 SNF440R46E6.7W23 SNF440R52E6.7W23 SNF440R54E6.7W23 SNS440R40E6.7W23 SNS440R46E6.7W23 SNS440R52E6.7W23 SNS440R54E6.7W23 TRSNH440-36 TRSNH440-40 TRSNH440-42 TRSNH440-46 TRSNH440-51 TRSNH440-54 TRSNF440-36 TRSNF440-40 TRSNF440-42 TRSNF440-46 TRSNF440-51 TRSNF440-54 TRSNS440-36 TRSNS440-40 TRSNS440-42 TRSNS440-46 TRSNS440-51 TRSNS440-54 TRSND440-36 TRSND440-40 TRSND440-42 TRSND440-46 TRSND440-51 TRSND440-54 TRSNK440-36 TRSNK440-40 TRSNK440-42 TRSNK440-46 TRSNK440-51 TRSNK440-54 HTSNH440-36 HTSNH440-40 HTSNH440-42 HTSNH440-46 HTSNH440-51 HTSNH440-54 HTSNF440-36 HTSNF440-40 HTSNF440-42 HTSNF440-46 HTSNF440-51 HTSNF440-54 HTSNS440-36 HTSNS440-40 HTSNS440-42 HTSNS440-46 HTSNS440-51 HTSNS440-54 HTSND440-36 HTSND440-40 HTSND440-42 HTSND440-46 HTSND440-51 HTSND440-54 HTSNK440-36 HTSNK440-40 HTSNK440-42 HTSNK440-46 HTSNK440-51 HTSNK440-54 HSNH440-36Z HSNH440-40Z HSNH440-42Z HSNH440-46Z HSNH440-51Z HSNH440-54Z HSNF440-36Z HSNF440-40Z HSNF440-42Z HSNF440-46Z HSNF440-51Z HSNF440-54Z HSNS440-36Z HSNS440-40Z HSNS440-42Z HSNS440-46Z HSNS440-51Z HSNS440-54Z HSNH440-36NZ HSNH440-40NZ HSNH440-42NZ HSNH440-46NZ HSNH440-51NZ HSNH440-54NZ HSNF440-36NZ HSNF440-40NZ HSNF440-42NZ HSNF440-46NZ HSNF440-51NZ HSNF440-54NZ HSNS440-36NZ HSNS440-40NZ HSNS440-42NZ HSNS440-46NZ HSNS440-51NZ HSNS440-54NZ HSNH440-36W1Z HSNH440-40W1Z HSNH440-42W1Z HSNH440-46W1Z HSNH440-51W1Z HSNH440-54W1Z HSNF440-36W1Z HSNF440-40W1Z HSNF440-42W1Z HSNF440-46W1Z HSNF440-51W1Z HSNF440-54W1Z HSNS440-36W1Z HSNS440-40W1Z HSNS440-42W1Z HSNS440-46W1Z HSNS440-51W1Z HSNS440-54W1Z HSNH440-36W1 HSNH440-40W1 HSNH440-42W1 HSNH440-46W1 HSNH440-51W1 HSNH440-54W1 HSNF440-36W1 HSNF440-40W1 HSNF440-42W1 HSNF440-46W1 HSNF440-51W1 HSNF440-54W1 HSNS440-36W1 HSNS440-40W1 HSNS440-42W1 HSNS440-46W1 HSNS440-51W1 HSNS440-54W1 HSNH440-36N HSNH440-40N HSNH440-42N HSNH440-46N HSNH440-51N HSNH440-54N HSNF440-36N HSNF440-40N HSNF440-42N HSNF440-46N HSNF440-51N HSNF440-54N HSNS440-36N HSNS440-40N HSNS440-42N HSNS440-46N HSNS440-51N HSNS440-54N HSNH440-36 HSNH440-40 HSNH440-42 HSNH440-46 HSNH440-51 HSNH440-54 HSNF440-36 HSNF440-40 HSNF440-42 HSNF440-46 HSNF440-51 HSNF440-54 HSNS440-36 HSNS440-40 HSNS440-42 HSNS440-46 HSNS440-51 HSNS440-54 HSND440-36W1 HSND440-40W1 HSND440-42W1 HSND440-46W1 HSND440-51W1 HSND440-54W1 HSND440-36N HSND440-40N HSND440-42N HSND440-46N HSND440-51N HSND440-54N HSND440-36 HSND440-40 HSND440-42 HSND440-46 HSND440-51 HSND440-54 HSNK440-36W1 HSNK440-40W1 HSNK440-42W1 HSNK440-46W1 HSNK440-51W1 HSNK440-54W1 HSNK440-36N HSNK440-40N HSNK440-42N HSNK440-46N HSNK440-51N HSNK440-54N HSNK440-36 HSNK440-40 HSNK440-42 HSNK440-46 HSNK440-51 HSNK440-54 HSNH440-36A HSNH440-40A HSNH440-42A HSNH440-46A HSNH440-51A HSNH440-54A HSNH440-36ZA HSNH440-40ZA HSNH440-42ZA HSNH440-46ZA HSNH440-51ZA HSNH440-54ZA HSNH440-40三螺桿泵 潤滑系統(tǒng)液壓泵 冷卻油泵 三螺桿泵 HSNH三螺桿泵 螺桿泵廠家 HSNH440-40NZ三螺桿泵在轉(zhuǎn)速1450/min（4級電機）壓力10Bar.黏度75cst.理論流量為4.8M3/H HSN三螺桿泵 HSNH(臥式)三螺桿泵、HSNS（立式）三螺桿泵、HSNF（支架式）三螺桿泵、HSND（多種安裝如后進(jìn)上出.后進(jìn)測出等）三螺桿泵、HSNK（懸掛式）三螺桿泵三螺桿泵構(gòu)造 1.主桿與從桿.螺桿就相當(dāng)于螺桿泵的心臟.其主要原理就是螺桿相互嚙合的螺桿沿軸向輸送工作介質(zhì)（主要材質(zhì)為54Cr, 38CrMoAl) 2.襯套與外殼.螺桿泵的襯套及外殼的長度應(yīng)至少能覆蓋一個導(dǎo)程的螺桿副.（襯套主要材質(zhì)為HT200/QT450-10/ZCuSn5Pb5Zn5/ZL109外殼為HT200/QT450-10） 3.軸套.軸套主要是用來固定從動螺桿以保證運轉(zhuǎn)平穩(wěn)（材質(zhì)為ZCuSn5Pb5Zn5/ZL109） 4.密封.螺桿泵密封分為.機械密封（適用于介質(zhì)潤滑性好溫度小于800)填料密封(適用于潤滑介質(zhì)較差粘度大溫度小于1500）和波紋管密封（適用于介質(zhì)粘度大溫度在2500） 5軸承.軸承可分為內(nèi)置軸承（一般介質(zhì)潤滑性好）外置軸承（介質(zhì)潤滑性差.粘度大） 6.前端蓋.后蓋.軸承座 .泵頭座為多為鑄件直接加工（材質(zhì)為HT200/QT450-10）HSNH440-40三螺桿泵/HSNH440-40NZ泵 HSNH440-40三螺桿泵性能參數(shù)簡介：品牌：泵 HSNH440-40三螺桿泵 HSNH440-40N三螺桿泵 HSNH440-40Z三螺桿泵 HSNH440-40NZ三螺桿泵 HSNH440-40W1三螺桿泵 HSNH440-40W1Z三螺桿泵流量：337.4L/min 壓力：1.0MPa 功率：7.46KW 轉(zhuǎn)速：1450r/min 驅(qū)動方式：電機驅(qū)動進(jìn)出口徑：125mm 、100mm HSNH440-40NZ三螺桿泵十個優(yōu)點 HSNH三螺桿泵優(yōu)點： 1.HSNH三螺桿循環(huán)油泵壓力和流量范圍寬闊。 流量范圍0.2～600m3/hzui高工作壓力可達(dá)6.3MPa。 2.HSNH三螺桿泵組輸送液體的種類和粘度范圍寬廣； 3.因為HSNH三螺桿泵內(nèi)的回轉(zhuǎn)部件慣性力較低，故可使用很高的轉(zhuǎn)速； 4.HSNH液壓油泵具有很好的吸入性和自吸能力； 5.HSNH潤滑油泵具有流量均勻連續(xù)，振動小，噪音低等特點； 6HSNH三螺桿泵與其它回轉(zhuǎn)泵相比，對進(jìn)入的氣體和污物不太敏感； 7.HSNH三螺桿泵結(jié)構(gòu)堅實，安裝保養(yǎng)容易。 8.HSN三螺桿泵，自吸。 9.HSNH由于部件通用組合系列化有多種結(jié)構(gòu)，可用于臥式，法蘭式和立式安裝。 10.根據(jù)HSNH三螺桿泵所輸送介質(zhì)需要還可提供加熱或冷卻結(jié)構(gòu)。 HSNH440-40NZ三螺桿泵設(shè)計原理 HSNH三螺桿泵是按國家標(biāo)準(zhǔn)GB10887-89設(shè)計、制造生產(chǎn)。HSNH三螺桿泵是轉(zhuǎn)子式容積泵，它是利用螺桿嚙合原理，依靠旋轉(zhuǎn)的螺桿在泵套內(nèi)相互嚙合，把被輸送的介質(zhì)封閉在嚙合腔內(nèi)，沿螺桿軸向連續(xù)勻速地推至排出口，為系統(tǒng)提供穩(wěn)定的壓力。三螺桿泵適用于輸送各種無腐蝕性油類及類似油和潤滑性液體。輸送液體的粘度范圍一般為3.0～760mm2/S(1.2～100°E)，高粘度介質(zhì)可通過加溫降粘后輸送。其溫度一般不超過350℃。 HSNH440-40NZ三螺桿泵結(jié)構(gòu)特點 HSN系列三螺桿泵由特殊型線構(gòu)成的螺旋面的主動螺桿轉(zhuǎn)動時，其動密封腔室將把液體由吸入口吸入并沿軸向連續(xù)、無脈動的輸送到排出口。主桿采用液壓平衡，從桿的軸向力支撐在后蓋上，并由液壓力驅(qū)動旋轉(zhuǎn)，因而螺桿型面僅傳遞液壓扭矩，并不受力，也無磨損，對全部傳動零件而言，均由被輸送介質(zhì)潤滑。主桿的徑向由平衡活塞定位，且借助于平衡活塞和軸套的間隙使高壓腔和密封腔分開，在密封腔內(nèi)裝有機械密封，腔內(nèi)的油液回油孔與泵的吸入腔相通，因而不受排出壓力的影響。由于部件通用組合系列化有多種結(jié)構(gòu)，可用于臥式（H），法蘭式（F）和立式（S）安裝。 根據(jù)所輸送介質(zhì)需要還可提供加熱或冷卻結(jié)構(gòu)。 HSNH440-40NZ三螺桿泵應(yīng)用范圍 在供熱設(shè)備中用做燃油噴油，燃油供應(yīng)和輸送泵。 在機械工業(yè)中用做液壓，潤滑和遙控馬達(dá)泵。 在化學(xué)石油化工和食品工業(yè)中用做裝載，輸送和供液泵。 在船舶上用做輸送、增壓、燃油噴射和潤滑油泵以及船用液壓裝置泵。HSN系列三螺桿泵型號 HSN440系列三螺桿泵 HSNH440-40NZ三螺桿泵HSNF440-40NZ三螺桿泵 HSNS440-40NZ三螺桿泵HSNE440-40NZ三螺桿泵 HSNH440-46NZ三螺桿泵HSNF440-46NZ三螺桿泵 HSNS440-46NZ三螺桿泵HSNE440-46NZ三螺桿泵 HSNH440-54NZ三螺桿泵HSNF440-54NZ三螺桿泵 HSNS440-54NZ三螺桿泵HSNE440-54NZ三螺桿泵