{"id":4215,"date":"2020-08-17T00:15:32","date_gmt":"2020-08-17T00:15:32","guid":{"rendered":"http:\/\/www.autolexicon.net\/?p=4215"},"modified":"2021-03-19T11:51:34","modified_gmt":"2021-03-19T11:51:34","slug":"valvetronic","status":"publish","type":"post","link":"https:\/\/www.autolexicon.net\/cs\/articles\/valvetronic\/","title":{"rendered":"Valvetronic"},"content":{"rendered":"

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Modern\u00ed benz\u00ednov\u00e9 motory automobilky BMW maj\u00ed variabiln\u00ed zdvih sac\u00edch ventil\u016f,<\/strong> tento syst\u00e9m nese n\u00e1zev Valvetronic. Obvykle je syst\u00e9m Valvetronic kombinov\u00e1n je\u0161t\u011b se syst\u00e9mem Double-Vanos<\/a>, tedy s variabiln\u00edm \u010dasov\u00e1n\u00edm ventil\u016f<\/strong>. Slou\u010den\u00edm t\u011bchto mechanism\u016f vznikaj\u00ed variabiln\u00ed rozvody (prom\u011bnn\u00e9 \u010dasov\u00e1n\u00ed i zdvih), kter\u00e9 p\u0159isp\u00edvaj\u00ed k dokonalej\u0161\u00ed v\u00fdm\u011bn\u011b n\u00e1pln\u011b v\u00e1lc\u016f p\u00edstov\u00e9ho spalovac\u00edho motoru<\/strong>. V\u00edce detail\u016f se do\u010dtete v \u010dl\u00e1nku o variabiln\u00edch rozvodech<\/a>.<\/span><\/p>\n

Pln\u011b variabiln\u00ed zdvih ventil\u016f dokonce umo\u017e\u0148uje konstrukt\u00e9r\u016fm nahradit funkci \u0161krtic\u00ed klapky.<\/strong> Motory se syst\u00e9mem Valvetronic sice klapku je\u0161t\u011b maj\u00ed, ale pouze pro nouzov\u00fd re\u017eim, jinak je klapka st\u00e1le otev\u0159ena. Nahrazen\u00edm \u0161krtic\u00ed klapky se tak poda\u0159ilo odstranit ztr\u00e1ty<\/strong> vznikaj\u00edc\u00ed turbulentn\u00edm proud\u011bn\u00edm vzduchu \u0161krtic\u00ed klapkou. Ur\u010duj\u00edc\u00edm faktorem mno\u017estv\u00ed sm\u011bsi, kter\u00e9 se dost\u00e1v\u00e1 do v\u00e1lc\u016f, je velikost zdvihu sac\u00edch ventil\u016f. Odstran\u011bn\u00edm \u0161krtic\u00ed klapky se podle BMW uspo\u0159\u00ed a\u017e 14 % paliva.<\/span><\/p>\n

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mechanismus syst\u00e9mu Valvetronic<\/em><\/strong><\/span><\/p>\n

Valvetronic je tedy kombinac\u00ed syst\u00e9mu <\/strong>Double Vanos<\/a>, kter\u00fd m\u011bn\u00ed polohu va\u010dkov\u00e9 h\u0159\u00eddele v\u016f\u010di klikov\u00e9 h\u0159\u00eddeli a\u017e o 60\u00b0, a elektromechanick\u00e9ho za\u0159\u00edzen\u00ed m\u011bn\u00edc\u00edho plynule zdvih sac\u00edch ventil\u016f<\/strong> od minim\u00e1ln\u00edho zdvihu (pouh\u00e9 0,3 mm) a\u017e po maxim\u00e1ln\u00ed zdvih (9,7 mm). Valvetronic II. a III. generace dosahuje rozmez\u00ed 0,18 mm to 9,9 mm. Zm\u011bna nastaven\u00ed mezi minim\u00e1ln\u00edm a maxim\u00e1ln\u00edm zdvihem trv\u00e1 pouh\u00fdch 300 milisekund. Za stejnou dobu se p\u0159enastav\u00ed i Double Vanos<\/a>.<\/span><\/p>\n

Poprv\u00e9 byl tento syst\u00e9m p\u0159edstaven v roce 2001 u modelu BMW 316 Compact s \u010dty\u0159v\u00e1lcov\u00fdm \u0161estn\u00e1ctiventilov\u00fdm z\u00e1\u017eehov\u00fdm motorem o objemu 1,8l\/85kW. Automobilka BMW postupn\u011b nasadila tento syst\u00e9mem do v\u0161ech sv\u00fdch motor\u016f. D\u016fvodem jsou ni\u017e\u0161\u00ed spot\u0159eba, vy\u0161\u0161\u00ed v\u00fdkon a rychlej\u0161\u00ed reakce na se\u0161l\u00e1pnut\u00ed plynov\u00e9ho ped\u00e1lu.<\/span><\/p>\n

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Popis funkce:<\/strong>
\nRozvodov\u00fd mechanismus sac\u00edch ventil\u016f je dopln\u011bn o mezivahadlo, kter\u00e9 tvo\u0159\u00ed spolu s b\u011b\u017en\u00fdm vahadlem spojen\u00ed mezi va\u010dkou a ventilem. Prost\u0159ednictv\u00edm pohybu excentrick\u00e9ho h\u0159\u00eddele ovliv\u0148uje mezivahadlo zdvih sac\u00edch ventil\u016f.<\/strong> Excentrick\u00fd h\u0159\u00eddel se pohybuje d\u00edky \u0161nekov\u00e9mu pohonu s elektromotorem.
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Tento zp\u016fsob ovl\u00e1d\u00e1n\u00ed ventilov\u00e9ho rozvodu je velice n\u00e1ro\u010dn\u00fd na p\u0159esnost v\u00fdroby<\/strong>. V\u0161echny d\u00edly rozvodu jsou vyr\u00e1b\u011bny s velkou p\u0159esnost\u00ed (nap\u0159. tolerance mezivahadla je pouze 0,008 mm). Odchylka otev\u0159en\u00ed zdvihu ventilu sm\u00ed \u010dinit pouze \u00b110 %. Proto jsou nav\u00edc mezivahadlo (mezip\u00e1ka) a vahadlo rozd\u011bleny do 4 klasifika\u010dn\u00edch t\u0159\u00edd. Toto ozna\u010den\u00ed je na d\u00edlech vyp\u00e1leno laserem. Minim\u00e1ln\u00ed zdvih (0,3 mm), je nav\u00edc ve v\u00fdrob\u011b m\u011b\u0159en a pop\u0159\u00edpad\u011b dvojice mezivahadla a vahadla je nahrazena jinou klasifika\u010dn\u00ed t\u0159\u00eddou.<\/span><\/p>\n

Va\u010dkov\u00e1 h\u0159\u00eddel a excentrick\u00e1 h\u0159\u00eddel je vedena ve speci\u00e1ln\u00edm l\u016f\u017eku, na kter\u00e9m je zachycen i elektromotor zaji\u0161\u0165uj\u00edc\u00ed nastavov\u00e1n\u00ed excentrick\u00e9 h\u0159\u00eddele. Toto l\u016f\u017eko je p\u00e1rov\u00e1no s hlavou motoru a z d\u016fvodu zachov\u00e1n\u00ed p\u0159esnosti nesm\u00ed b\u00fdt jednotliv\u011b vym\u011b\u0148ov\u00e1no.<\/span><\/p>\n

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