种子含水率在线测量系统_裘揆.pdfVIP

20 06 9 37 9 * 裘　揆　陈乐生　赵春宇　陈大跃 A/D 2 , : : S237 , , ; 3 :A 3 ; , 3 On-line Measuring System of Seed Moisture Content Qiu Kui Chen Yuesheng Z hao Chunyu Chen Dayue ( S hanghai J iao T ong Univ ersity ) Abstract An o n-line measur ing syst em of seed moist ure cont ent is developed in t his paper. T he mechanical sy st em is mainly co mpo sed o f t w o ho rizontal concentr ic cylinders. T he inner cy linder rotat es and continuo usly delivers seeds int o t he measur ing posit io n betw een t he tw o cy linders. A st ray-imm une sw it ching circuit is em ploy ed t o m easur e the capacit ance of t he t w o st eel plat es. T he l ow er st eel plate also serves as t he plat for m of t he w eighing unit in t he syst em . T he t em perature is sensed by precise t her mal t ransducer. T he measur ed inf orm ation of t he capacit ance, w eig ht and t em perat ur e is o ut put in dig it al for mat via A/ D co nv ert er. Ex perim ent s are m ade upon t he t hree unit s wit h know n capacitance, w eig ht and t em perat ur e respect ively, and t he infl uence of t em perat ure and atm osphere humidit y to t he capacit ance is measured also. T he accuracy , reliabilit y and feasibility of the syst em are t herefo re evaluat ed. Key words Seeds, Moist ure cont ent , On-line m easur em ent , Sy st em s desig n , , , , : 2005 03 28 *( : 2000 3 2) , 200030 [ 1] , , , 120 2 0 0 6 1 2 105 m m 4 4 , 1b , 100 m m , 1 170 mm , , , , , , 1 Fig . 1 O n-line measuring system o f seed m oisture content (a) ( b) 1. 2. 3. 4. 5. 6. 7. ,1 , , , , Cx C s2 Cp 1 Cp 2 Cp 3 Cp 4 2b Cx S 1 S2 ,S3 S4 , S1 S 2 Cx S 4 S1 Cp 1 Cp 3 Cs2 ; ; Cx , c , V0 Cx , , 2 , [ 2] , ; Cs1 ; , :, , Cx Vc; , S3 S 4 , , Cx , ,b b , Cp2 Cp4 , C s1 V0 [ 3] V0( ) = f VcRf Cx : ( 1) Vc , , f CxVc ( 1) , ) , pF ( 105 Hz ( 15 r/ m in) , , ,, , , , ,4 2 2. 1 2. 1. 1 pF , , , pF , 2 F ig . 2 Str uctur e and w or king pr inciple of micr o-ca pacit y measuring cir cuit (a) ( b) 2. 1. 2 U 1A ( 74HC393) , U2 U3 U 1A 3 6 M Hz U1A ( 74H