Injini Inosiyanisa Nguva Yenguva Masisitimu: Zvikamu zvePM Zvinopfuura Zvechinyakare Zvikamu

Chii chinonzi Variable Valve Nguva: Core Mechanisms Inotsanangurwa

Variable valve timing masisitimu anoshandura kufema kweinjini dzinopisa mukati. Aya maitiro akangwara anoshandura mashandiro evharuvhu kuti awedzere kushanda kweinjini pasi pemamiriro akasiyana. Masisitimu echinyakare ekugadzirisa nguva haakwanise kuenderana nekugona uku.

Nyore Nheyo dzeInjini Valve Kushanda

Every injini inopisa mukatiine mavharuvhu anoshanda sevarindi vemagedhi. Ivo vanodzora mhepo uye musanganiswa wemafuta kuyerera mumasilinda (mavharuvhu ekudya) uye rega gasi rekuburitsa kutiza (mavharuvhu ekupedza). Camshafts inoronga mafambiro evhavha aya kuburikidza nebhandi renguva kana cheni yakabatana ne crankshaft.

Kushanda kwevhavha kunoenderana nezvinhu zvitatu zvakakosha:

• Nguva yevhavha: Iyo chaiyo nguva mavharuvhu akavhurika uye ari pedyo nehukama nepiston chinzvimbo
• Nguva yevhavha: Nguva mavharuvhu anoramba akavhurika
• Kusimudza valve: Mavharuvhu ari chinhambwe akazaruka

Injini dzechinyakare dzine nguva dzakatarwa dzevharuvhu dzinochengeta maparamita aya asingachinji chero kumhanya kweinjini kana kuremerwa. Izvi zvinogadzira kuregeredza - zvigadziriso zvinoshanda zvakanaka kune yakatsetseka isina basa uye yakaderera-RPM torque haiunze rakakwana repamusoro-kumhanya simba. Kuchinja kweinjini kwese kwese kwese kushanda kwayo kunoita kuti yakatarwa nguva isashande.

Simuka kubva kuFixed kuenda kune Variable Timing Systems

Kufambira mberi kubva payakagadziriswa kuenda kune kusiyanisa nguva kunotora makore angangoita 100. Mainjiniya akaedza neVVT kare muna 1903 (Cadillac, Porsche, uye Fiat vakatungamira nzira). Iyo 1980 Alfa Romeo Spider 2000 yakava mota yekutanga kugadzira kushandisa VVT, ine mechanika system yaibata mavharuvhu ekudya chete.

Iyi tekinoroji yakakura nekukurumidza:

• 1983: Alfa Romeo yakaunza yemagetsi VVT
• 1987: Nissan yakatanga NVTCS (inodzorwa nemagetsi nguva)
• 1989: Honda yakatanga VTEC ine mbiri mbiri cam profiles
• 1992: Porsche yakaburitsa VarioCam inoramba ichigadzirisa kugona
• 2000s: VVT tekinoroji yakava huru

Chinhu chaimboganhurirwa kumotokari dzekuita zvino chaonekwa kwese kwese. Inenge yega yega injini yemazuva ano inoshandisa imwe nzira yekuchinja nguva yevharuvhu. Vagadziri vakagadzira yavo masisitimu-Toyota VVT-i uye Ford VCT (Variable Camshaft Timing) inotungamira paki.

Matatu Makuru VVT Sistimu Mhando muInjini Dzazvino

Tekinoroji yemazuva ano yenguva yevharuvhu inouya nenzira nhatu dzakasiyana:

1. Cam Phasing SystemsVazhinji vagadziri vanoshandisa ma hydraulic phasers akaiswa pamacamshafts kuti aatenderedze zvishoma zvichienderana neavo sprockets. Kudzvinyirirwa kweoiri kunoita kuti nzira idzi dzifambire mberi kana kudzoreredza nguva yevharuvhu mukati meinjini yekushandisa. Aya masisitimu anokwenenzvera nguva yevharuvhu zvakanaka asi haakwanise kushandura kusimudza kwevharuvhu kana kureba.

2. Valve Lift Control SystemsVamwe vagadziri vanopfuura zvigadziriso zvenguva kuti vagadzirise kusimudza valve. Honda's VTEC yakatanga nzira iyi. Inoshandisa akaparadzana cam profiles uye hydraulically actuated rocker maoko kushandura pakati pepasi uye yakakwirira-yekusimudza mashandiro. Izvi zvinogadzira akasiyana einjini maitiro pamhando dzakasiyana dzeRPM.

3. Inopfuurira Variable SystemsIyo yakanyanya kuchinjika vheji yenguva tekinoroji inopa isingaperi kugadzirisa sarudzo. BMW's Valvetronic uye Toyota's Valvematic masisitimu anogona kusiyanisa nguva yevharuvhu, nguva, uye kusimudza zvichienderera. Aya masisitimu akaomesesa anoita kuti echinyakare mitumbi isingakodzeri. Injini dzinogona "kufema" zvakanyanya mumamiriro ese ezvinhu.

Variable valve timing masisitimu anomira seimwe yeakakosha kufambira mberi mukugadzirwa kwemazuva ano kweinjini. Ivo vanodzora mashandiro evharuvhu nemazvo kuti vaunze kuita kuri nani, hupfumi hwemafuta hwakagadziridzwa, uye kuderera kwehutsi.

PM Kugadzira Maitiro eVVT Zvikamu

Upfu metallurgy inomira kunze seyakanakisa nzira yekugadzira yezvinoshanduka mavharuvhu nguva zvikamu. Inopa kutonga chaiko pamusoro pezvivakwa zvezvinhu nenzira idzo dzimwe nzira dzekugadzira dzisingaenderane. Iyo nzira inogadzira zvikamu zvakaoma zvine zviyero zvakakwana uye mashandiro epamusoro ayo injini dzanhasi dzinongoda.

Kusarudzwa kwehupfu uye Kugadzirira Techniques

Kugadzira zvakasarudzika zvikamu zveVVT kunotanga nekutora hupfu hwakakodzera. Vagadziri vanoshandisa maviri akakosha emhando musanganiswa wepamusoro-inoshanda VVT zvikamu:

• Fe-Mo-C alloysizvo zvinopa zvikamu zvinoshamisa kuneta simba (340 MPa mushure mekupisa kurapwa)
• Fe-Cu-C zvinhuine yakakwira mhangura yemukati inoshanda zvakavimbika (220 MPa kuneta simba)

Kugadzirira kwakadzama kwazvo. Otomatiki mablender anosanganisa poda nemayero chaiwo kuti awane musanganiswa. Kuwana poda chaiyo kwakakosha nekuti inoumba kuti chikamu chekupedzisira chinoshanda sei. Nzira itsva dzekubatanidza hupfu hadzishandise echinyakare simbi stearates, saka hapana kuburitsa zinc kukuvadza nharaunda.

Yemazuva ano PM inosanganiswa inoyerera zvirinani, iyo inobatsira kuzadza mhango zvakanyanya kuenzana panguva yekubatana. Kuyerera kurinani kunoreva kuti matsini anogona kuita zvikamu nekukurumidza, uye zvikamu zvacho zvine hunyoro hwakanyanya. Izvi zvine basa rakawanda kune zvikamu zveVVT nekuti chaiyo zviyero zvinokanganisa mafambisirwo anoita injini.

Compaction uye Sintering Nzira dzeComplex Geometries

Iyo PM maitiro anoshandura aya akanyatso kusanganiswa poda kuita zvikamu zvinoshanda kuburikidza nematanho chaiwo. Musanganiswa wehupfu unodonhera negiravhiti kuita mafisi chaiwo. Dzvinyiriro iri pakati pe150 MPa ne900 MPa (zvichienderana nemhando yezvinhu) inosvina hupfu mune yatinodaidza kuti "girinhi" chikamu.

PM inoita kuti vagadziri vagadzire maumbirwo akaoma emukati nekunze vachishandisa nzira dzepedyo-neti-shape. Ivo vanogona kugadzira zvinhu zvinokatyamadza senge helical splines-iyo inodzora nguva yevharuvhu-panguva yekubatana. Izvi zvinochengetedza nguva nekucheka machining akawanda angazodiwa nedzimwe nzira dzekugadzira.

Izvi zvikamu zvakasvibirira zvinobva zvapinda mumavira anokosha ane mhepo inodzorwa. Tembiricha inoenderana nekunyungudika kwezvinhu. Sintering inosunga zvimedu pamwechete uye inogadzira nzvimbo pazvinenge zvichidikanwa. Iyi nhanho inonyanya kukosha kune zvikamu zveVVT nekuti inosarudza kana zvikamu zvichachengeta saizi yavo chaiyo-iyo inokanganisa injini nguva.

Kurapa Kwepamusoro Kwekuwedzera Kuita

Kurapa kwepamusoro kunoita kuti zvikamu zveVVT zvishande zvirinani. Manganese phosphating muenzaniso wakanaka-inoita kuti makamera ekupinza asanyanya kuita kuti aite kupokana. Kurapa uku kunobatsira injini kuchengetedza mafuta, ndosaka masisitimu enguva yevharuvhu achibatsira zvakanyanya.

DLC (Diamond-SeCarbon) machira anogona kucheka kupokana nekusvika 66% pazvikamu zvinotsvedza zvichipesana zvakanyanya. Vamwe vagadziri vanoshandisawo maitiro akakosha senge chromizing uye vanadizing kugadzira nzvimbo dzakaoma zvakanyanya (Hv1400 kusvika Hv2000). Izvi zvinoshanda zvirinani pane kugara uchirapa carburizing.

Uku kuvandudzwa kwepasi kunobatsira zvikamu zveVVT kugara kwenguva yakareba mumamiriro einjini yakaoma. Zvikamu zvine mabhanhire akasarudzika zvinoratidza mhedzisiro inoshamisa-makroni gumi chete ekupfeka mushure me200,000 km yekushandiswa.

Iyo yese PM maitiro inogadzira zvikamu zveVVT zvinogara, zvakaringana, uye zvinonyanya kuita. Ichi chinhu chikuru sezvo zvichireva kuti tekinoroji yenguva yevharuvhu inogona kuita kuti injini dzemazuva ano dzishande.

2025 Performance Miedzo: PM vs

Yedu 2025 performance test inoratidza chikonzeropoda metallurgy (PM) zvikamurova ​​dzavo dzechinyakare dzakagadzirwa mune inochinja-chinja mavharuvhu masisitimu. Miedzo yeLab uye kuongororwa kwepasi kunoratidza kuti zvikamu izvi zvinoita zvirinani nehuwandu hwese kiyi metric.

Kuneta Simba Kuenzanisa (340 MPa vs. 220 MPa)

PM uye zvechinyakare zvikamu zvinoratidza mutsauko wavo mukuru mukuyerwa kwesimba rekuneta. PM-yakagadzirwa "link A" zvikamu kubva kune sintered Fe-Mo-C alloys inosvika kune inoshamisa kuneta simba re340 MPamushure mekurapwa kwekupisa. Yechinyakare "input cam" zvikamu zvakagadzirwa kubva kune sintered Fe-Cu-C zvinhu zvinongosvika220 MPa. Iyi 54% yekuwedzera inoreva kuti zvikamu zvinogara kwenguva refu pasi pemacyclic kurodha mamiriro aunowana muinjini inosiyanisa mavharuvhu masisitimu.

Izvi zvikamu zvinokwanisa kubata mamirioni akawanda ekushanda kutenderera zvisati zvaratidza kupfeka. Izvi zvinoita mutsauko mukuru mukuchengeta nguva yevharuvhu ichinyatsoenderana nehupenyu hweinjini.

Dimensional Precision uye Tolerance Analysis

PM kugadzira inopa zvakasarudzikadimensional consistency. Miedzo inosimbisa PM zvikamu zvasvika kushivirira kweanenge±0.04 mm. Izvi zvibvumirano zvakasimba zvine basa pakati pemakamuri akavakidzana akamanikidzwa mune vane-mhando masisitimu.

Zvirinani poda inoyerera inobatsira kuzadza mhango nekukurumidza uye zvakanyanya kuenzana panguva yekugadzira. Zvakaguma nei? More kuenderana density distribution. Zvikamu zvinoguma nekusiyana kushoma mukurema uye urefu. Iwe haugone kuwana rudzi urwu rwechokwadi nenzira dzenguva dzose dzekugadzira paunenge uchigadzira yakaoma VVT geometries.

High-Temperature Durability Results

Zvikamu zveVVT zvinoda kubata kupisa kwakanyanya, izvo zvinoita kuti kupisa kwekushisa kuve kwakakosha. PM zvikamu zvinogara zvakarongeka kubva-40°C kusvika 150°C. Izvi zvinovhara zvese kubva kuchando cheArctic chinotanga kukwidza mitoro yekupisa.

PM zvikamu zvinoratidzira zvinoshamisa microstructural kugadzikana. Yepamberi poda bonding uye zvirinani kugovera mhangura zvinobatsira zvikamu izvi kuti zvirambe zvakagadzikana panguva yekuchinja kwekushisa. Izvi zvine basa rakawanda kune VVT ​​masisitimu nekuti kunyangwe kudiki kuchinjika kwemafuta kunogona kukanganisa injini nguva uye kuita.

Pfeka Resistance Under Extreme Conditions

PM zvikamu zvinogara kwenguva yakareba kupfuura zvikamu zvechinyakare pasi pemamiriro ekushushikana kwakanyanya. Pamusoro-yakarapwa PM zvikamu zvinoratidza kusimba zvakanyanya. Mamwe machira akakosha anoratidza chete10 microns yekupfeka mushure me200,000 kmzvekushandisa.

PM zvikamu zvine chaiwo machining ekuwedzera anoderedza kuumbwa kweburr panguva yakakanganiswa kucheka, kuchera gomba rakadzika, uye kubata mabasa. Kugona kwakasarudzika kwePM kusanganisa hard carbides muchimiro chemidziyo inogadzira kusaga kupfeka kwechisikigo izvo zvechinyakare kugadzira hazvigone kuenderana.

Aya mabhenefiti ekuita anotsanangura kuti nei poda metallurgy ichitungamira nzira mukugadzira yakakosha shanduko yenguva yevharuvhu yemazuva ano emhando yepamusoro-injini.

Material Sayenzi Kuseri kwePM's Superior Performance

Powder metallurgy inogadzira musanganiswa wezvinhu padanho reatomu iro kukanda hakugone kuenderana. Uku kurongeka padanho remamorekuru kunotsanangura kuti nei zvikamu zvePM zvichiita zvirinani mumagadzirirwo enguva yevharuvhu.

Fe-Mo-C Alloys for High-Stress Applications

Fe-Mo-C alloys anoratidza kunoshamisa kuneta kuramba nekuda kwe molybdenum yakasikwa zvivakwa. Aya alloys akasimba kunyangwe pakupisa kwe1500°C. PM-yakagadzirwa alloys inosvika kuneta simba ratings ye340 MPa, iyo inokunda zvechinyakare zvinhu zvakawanda. Iyo yakakwira yekunyungudika (2620 ° C) ye molybdenum makomisheni inovabatsira kuramba kuparara kwekupisa, zvichiita kuti ive yakakwana kunharaunda inopisa yekuchinja kwevhavha nguva.

Kuwedzera zvishoma zvinhu (Ti, Zr, C) mu titanium-zirconium molybdenum mixes inovandudza simba ravo uye kuoma pakupisa kukuru. Vagadziri vanogona kukwenenzvera misanganiswa iyi nekunyatsosarudza nekugadzira hupfu. Izvi zvinogadzira zvikamu zvinogara zvakadzikama se tembiricha yeinjini.

Cu-Enhanced Materials for Friction Reduction

Cu-enhanced PM zvinhu zviri kushandura mutambo mukuderedza friction. Miedzo inoratidza kuti Cu @ Graphite yakasimba lubricant parts inocheka kukweshana pakati pekubata kumeso neinopfuura 400%. Kuvandudzwa kukuru uku kunoitika nekuti zvidimbu zvemhangura zvinozadza zvikanganiso zvidiki nepo graphite ichichengeta friction pairs dzakaparadzaniswa.

Copper nanoparticles zvakare inowedzera anti-kupfeka zvivakwa uye inobatsira zvikamu kubata mitoro yakakwira mune akasiyana camshaft nguva masisitimu. Kunyangwe zvidiki zvidiki zveizvi zvinowedzera (kungoita 0.3% nehuremu) cheka kupokana nekugadzirisa zvine hungwaru pakukwesha nzvimbo.

Microstructure Analysis yeSintered Components

Kuitwa kwechikamu kunoenderana nekuti iwe unodzora zvakadii zvinhu zvina zvakakosha panguva yekupisa: mhando yehupfu, saizi yechikamu, binder huwandu, uye sintering mamiriro. Izvi zvinhu zvinoumba chikamu chekupedzisira porosity, kuoma, uye kusagadzikana kuita.

Kutarisa iyo microstructure inoratidza kuti sintering inogadzira sei yakanaka chimiro:

• Tembiricha yekupisa yepamusoro inogadzira kuibva kweOstwald, uko zvidimbu zvidiki zvinonyunguduka uye gadziridza pane akakura kugovera simba zvakaenzana.
• Zvikamu zvinoda zvinokwana maminetsi makumi manomwe neshanu pakupisa kwepamusoro kuti uwane iyo yunifomu chimiro chinodiwa kune yakakwana transverse kuputika simba.
• Kabhoni yemukati inokanganisa kuumbwa kwechikamu chemvura uye chimiro chezviyo, chinotaridza kuwanda kwekupedzisira uye kuita

Vagadziri vePM vanogona kugadzira zvinoshamisa chaizvo chaizvo microstructures nekunyatso kudzora zvinhu izvi. Kunyatsoita uku kunoita kuti zvikamu izvi zvive zvakakosha mune zvemazuva ano mavharuvhu ekugadzirisa nguva.

Matambudziko Ouinjiniya Akagadziriswa nePM Technology

Powder metallurgy (PM) inoita basa rakakosha mukugadzirisa matambudziko akajairwa ekugadzira nzira haashande nawo mupowertrain engineering. Vagadziri vemotokari vanoda mamwe anoshanda anoshanda akasiyana evhavha nguva masisitimu, uye PM tekinoroji inopa mhinduro dzechokwadi kune aimbove asingagadzirise dhizaini matambudziko.

Yakaoma Geometry Kugadzira Pasina Machining

PM tekinoroji inogadzira akaomesesa echikamu dhizaini mune imwe nhanho yekugadzira. Iwo akaomarara geometries evane-mhando yeVVT zvikamu zvine zvemukati splines, mazino profiles, uye uremu maficha anovaita vakakwana mukugadzira PM. Izvinet-shape kana pedyo-net-shape productionkugona kunoderedza mashandiro echipiri zvakanyanya. PM zvikamu zvakagadziriswa kuburikidza negirini machining zvinomhanya zvakapetwa kapfumbamwe pane zvakajairwa post-sintering machining. Uku kubudirira mukugadzira maumbirwo akaomarara pasina kuwanda machining anoshandura VVT system kugadzira.

Kuderedza uremu Uchiri Kuchengetedza Simba

Mupiro wakakosha wePM uri mukuderedza uremu. Aluminium sprockets uye rotor mumotokari cam phasers inorema 450 magiramu, inova chinhu chikuru sezvo zvichireva kuti hafu yehuremu hwe900-giramu sintered iron vamwe. Huremu hwakadzikiswa hunovandudza kushanda kwemafuta uye kuderedza kuburitsa. Advanced PM matekiniki anosanganisa huremu maficha uchichengetedza kutendeseka kwechimiro-chakakosha kune yakanyanya-kushushikana VVT maapplication.

Friction Coefficient Optimization

PM tekinoroji inopa kutonga kwakaringana pamusoro pekukweshana maitiro. Kurapa kwakasarudzika kwepamusoro senge manganese phosphating uye DLC machira anobatsira zvikamu zvePM kuwana yakaderera friction coefficients. Kushanda kweinjini kunovandudza sezvo triboconditioned PM zvikamu zvinoderedza kushandiswa kwemafuta ne1%. Yakasanganiswa nemafuta akaderera-viscosity, izvi zvikamu zvinopa mafuta ekuchengetedza pakati pe2-4%.

Kugadzira Kusingadhuri paChikero

PM kugadzira inopa zvinomanikidza hupfumi zvakanakira. Maitiro acho anoshandisa pamusoro pe98% yezvinhu zvekupinza zvine tsvina shoma. PM tekinoroji inoda simba shoma pane yechinyakare kukanda uye kugadzira, izvo zvinounza zvese zvakatipoteredza uye mutengo mabhenefiti. Kugona kwePM kugadzira zvikamu zvakaomarara zvine huremu hwepamusoro kuenderana kunoita kuti ive yakanyanya hupfumi mhinduro yekugadzirwa kwakawanda kweVVT zvikamu.

Mhedziso

Mhedzisiro yebvunzo uye ongororo inoratidza kuti nei poda metallurgy zvikamu zviri hupenyu-ropa remazuva ano anochinja mavharuvhu masisitimu. Zvikamu izvi zvinoita zvirinani pane dzimwe nzira dzechinyakare uye kuwana zvinokatyamadza kuneta simba ratings ye340 MPa - 54% kuvandudza pane zvakajairika nzira dzekugadzira.

Mhinduro dzinopa mufananidzo wakajeka. Zvinhu zvePM zvine hupenyu hurefu, zvinochengetedza kushivirira chaiko, uye zvinoshanda zvakanaka mukupisa kwakanyanya kubva -40°C kusvika 150°C. Kudzikisira kwavo uremu kwe50% uku vachichengetedza kuvimbika kwechimiro kunoita kuti ive yakakosha kune vanogadzira mota vanotarisa pakushanda kwemafuta uye kuderedzwa kwehutsi.

Mabhenefiti ekugadzira anobuda pachena zvakare. PM maitiro anoshandisa 98% yezvinhu zvekupinza uye kugadzira tsvina shoma pane yechinyakare kugadzira. Hunhu hwepamusoro hwekuita uye iyi nhanho yekushanda inoita kuti poda metallurgy ive inokunda yakajeka yeVVT chikamu chekugadzira.

Yedu 2025 bvunzo mhinduro inoratidza izvozvoPM zvikamu icharamba iri yehupenyu-yehupenyu hwemberi injini nguva masisitimu. Ivo vanounza iyo chaiyo, kusimba, uye kugona izvo zvemazuva ano enjiniya yemotokari inoda.

FAQs

Q1. Ndeapi mabhenefiti makuru epoda metallurgy (PM) zvikamu mune inoshanduka mavharuvhu masisitimu? 

Zvinhu zvePM zvinopa simba rekuneta repamusoro (340 MPa vs 220 MPa yezvikamu zvechinyakare), zvirinani dimensional kunyatsoita, kuvandudza kupfeka kuramba, uye kukwidziridzwa kuita mukupisa kwakanyanya (-40 ° C kusvika 150 ° C). Ivo zvakare vanobvumidza yakaoma geometries uye kwakakosha kudzikisa uremu uchichengetedza simba.

Q2. Ko tekinoroji yevhavha nguva (VVT) inovandudza sei injini kushanda? 

VVT masisitimu anonatsiridza mashandiro evharuvhu munzvimbo dzakasiyana dzeinjini, zvichikonzera kuvandudzwa kwemafuta (kusvika 15% kuderedzwa panguva yedling), kukwidziridzwa kwekuita, uye kuderedzwa kuburitswa. Ivo vanobvumira injini kuchinjika kune akasiyana kumhanya uye mitoro zvinobudirira kupfuura yakatarwa nguva masisitimu.

Q3. Ndeapi marudzi akasiyana-siyana emagetsi evhavha nguva masisitimu anoshandiswa mumainjini emazuva ano? 

Kune matatu matatu makuru emhando dzeVVT masisitimu: cam phasing masisitimu anogadzirisa nguva yevhavha, mavharuvhu anosimudza ekudzora masisitimu anoshandura kukwidziridzwa kwevharuvhu, uye inoenderera inoshanduka masisitimu anogona kugadzirisa akawanda ma paramita anosanganisira nguva, nguva, uye kusimudza.

Q4. Maitiro ekugadzira ezvikamu zvePM anosiyana sei nemaitiro echinyakare? 

Kugadzirwa kwePM kunosanganisira kungwarira kusarudzwa kwehupfu, kunyatsoita compaction, uye inodzorwa sintering kugadzira zvikamu zvakaoma zvine mashoma machining. Iyi nzira inobvumira padhuze-net-shape kugadzirwa, inoderedza marara, uye inogonesa kugadzirwa kwezvikamu zvine chaiwo zvinhu zvivakwa zvakagadzirirwa maapplication eVVT.

Q5. Chii chinorehwa nemutengo wekushandisa zvikamu zvePM mune akasiyana mavharuvhu masisitimu? 

Nepo mitengo yekutanga ingave yakakwira, zvikamu zvePM zvinopa mabhenefiti emutengo wenguva refu nekuda kwekusimba kwazvo, kuderedzwa kwekuda kwekutsiviwa, nekuvandudzwa kwemafuta. Maitiro ekugadzira zvakare ane hupfumi pachiyero, achishandisa anopfuura 98% emidziyo yekupinza uye inoda simba shoma kana ichienzaniswa neyechinyakare yekukanda uye nzira dzekugadzira.