VVT yog lus Askiv luv ntawm Variable Valve Timing. Lub cam txoj hauj lwm ntawm lub camshaft ntawm cov tsoos cav yog tsau, nws yog synchronized nrog rau theem ntawm lub cav crankshaft, uas yog, lub qhib thiab kaw lub kaum sab xis (lub sij hawm) ntawm lub intake valve thiab lub tso valve tsis hloov.

Yog li ntawd, qhov zoo tshaj plaws Nws yog ib qho nyuaj rau ua tiav qhov zoo tshaj plaws high-ceev kev ua tau zoo nyob rau tib lub sij hawm nrog lub low-speed valve lub sij hawm ntawm lub ", uas yog, nws yog tsis yooj yim sua kom sib npaug cov kev xav tau ntawm idle speed stability, low-speed torque output. thiab high-ceev tso zis. Yuav kom daws tau qhov sib txawv ntawm lub cav rau lub sijhawm valve nyob rau hauv qhov kev kub ceev thiab qis qis, ib qho kev hloov pauv lub sijhawm (VVT) system tau txais yuav. Lub hydraulic actuator (VVT phaser) yog ntsia rau ntawm lub hauv ntej kawg ntawm lub camshaft, thiab hydraulic siab yog tswj electronically. Txoj hauv kev los hloov cov theem ntawm lub camshaft txheeb ze rau lub crankshaft kom ua ntej lossis retard lub sij hawm valve. Lub VVT ​​phaser thiab camshaft sib dhos yog qhia hauv daim duab hauv qab no.

Tam sim no, feem ntau cov roj av cav tau nruab nrog ntau hom VVT tshuab. Tshwj xeeb tshaj yog rau cov cav nrog cov qauv emission siab dua, lawv tau nruab nrog dual VVT mechanisms (siv thiab tso camshafts yog nruab nrog VVT phasers). Qhov tseeb, VVT system ua tau raws li qhov xav tau ntawm kev ua haujlwm sib txawv thiab ua tiav cov txheej txheem kev sib raug zoo los ntawm kev hloov lub valve sib tshooj lub kaum ntse ntse. Feem ntau, nws muaj qhov zoo hauv qab no:

(1) Cov theem ntawm qhov nkag thiab tso tawm camshafts tuaj yeem hloov kho, uas tuaj yeem nce ntxiv los ntawm kev tswj hwm. Lub valve sib tshooj lub kaum sab xis ua rau lub cav cua nkag.

(2) Txo qhov seem ntawm cov pa roj coefficient thiab txhim kho kev them nqi.

(3) Txhim kho lub zog ntawm lub cav thiab lub zog, thiab txhim kho roj kev lag luam zoo.

(4) Obviously txhim kho lub idle ceev stability, yog li tau txais kev nplij siab thiab txo emissions.