banjalukaforum.com

Nadam se da nije dizel

Koje godiste, jel to pod "uzmi, vozi" treba da shvatim da i nije neko auto

How can I make my car quieter? What kind of sound insulation is available?

A:There are a variety of products available on the market
that you either glue on the car's inner body panells or
spray into cavities. These products are available from
either car audio stores, or electronic stores. Do shop
around because price varies alot.

The effects of this insulation varies with the type of
material used and how and where it was installed.
Generally, the more you cover up, sometimes even doubling
up in certain areas, the greater reduction in noise. It
will also improve the sound quality of your car due to
the fact you have lowered the resonance frequency.

VWs generally produce most of their noise in the engine
compartment, followed by the entire exhaust system, the
wheel wells (rear), and after that it's probably a toss
up whether your doors or your roof makes the most noise.
For the more recent models, VW actually did a fairly good
job at insulating the car, however, there is always room
for improvement.

Start with the easily accessible areas that have bare
sheet metal, and that sound "tinny" when struck. Most
people start by insulating the trunk floor, rear wheel
wells, the spare wheel well, and underneath the rear
seat. Those areas are right above the muffler or the
wheels with little or no insulation. In my Corrado G60, I
noticed a reduction in buzzing coming from the rear. The
car is now noticeably quieter in the rear versus the
front, while previously it was about the same. Some have
reported results up to 10 dBa reduction, which is rather
significant (a 3dB reduction = 1/2 the noise).

If you are more ambitious, go underneath the carpets as
well. However, depending on the model of the car, VW
probably beat you to it already and it's unclear whether
it'll make much of a difference.

The next areas to treat are harder. If your car does not
have foam underneath the hood, add it. Next try
insulating the fire wall, but be aware that that area
gets very hot and you need suitable materials for that
area.

The top is like a bloody drum, in some respects, and
anything done here to deaden it or change the harmonic
frequency helps. Note that the foam insulation that vw
uses deteriorates after a period of time, especially the
headliner.

Cut the mats to size, than pull of the adhesive cover and
stick it to the body panel. Some products require a heat
gun (hair dryer works too) to establish a firm bond, or
to get the material sufficiently pliable. Some apply
additional glue, such as 3M "Spray 99 adhesive" to get a
good bond.

Probably the most popular product in the USA is that made
by Dynamat. Another brand name with a similar product is
AccuMat by Scoshe Industries. Both Dynamat and AccuMat
sell a variety of types, the thin sheets are generally
for covering body panels, the thicker for under carpets,
and a high temp mat/foam sheet that can be used in the
engine compartment. Other brand names are: Kentamat,
Sonex, a foam padding, designed much like the walls of
an anechoic chamber, available in various thicknesses and
densities, and used to deaden or absorb sound in rooms,
chambers, or instrument areas.

Dynamat is some kind of asphalt sheet with glue on one
side, while AccuMat is made out of latex and the thicker
ones out of foam. Some speculate that Dynamat is nothing
more than Bitumen roofing paper, and therefore any dense
material would work. Some have had limited success with
using asphalt roofing material such as "Elastophene Flam"
which is an SBF membrane roofing material (it's black,
heavy, fireproof, 1/8" thick and relatively cheap) or
simple vinyl floor tyles which the AccuMat thin product
resembles.

I have used the thin sheets from both Dynamat and
Accumat, and they both have pros and cons. Accumat costs
more, adheres better but does not dampen as well. Dynamat
does not adhere well at all (unless you use a heat gun or
spray on adhesive), dampen better than Accumat
(subjective opinion) but out of the box, Dynamat STINKS
majorly. Applying this fresh dynamat over a surface that
get hot (i.e., above the exhaust system) will noticeable
smell up your car. The problem goes away over time, but
it's better if you leave the sheets to bake and air out
in the sun for a couple of weeks. Dynamat does sell a low
oder version, but that's even more expensive and smaller
than their regular sheets.

ADVOTECH (CA) sells a product called RattleTrap which is
a rubbery goo (it reminded me a bit of Plummers' Putty
actually) you squeeze into cavities that buzz.

Svi moderni dizeli imaju plutajući zamajac radi ublažavanja vibracija i ostalih (uglavnom) gluposti. Dosta ljudi to prepravlja na obični zamajac, čitava industrija se razvila

Kako bez nosaca? Uzmi ih cisto radi vizuelnog utiska. A za tu bijelu neces vjerovati kako je dobra Vjeruj mi.

Btw. ako vam je prebucno, investirajte nesto love u zvucnu izolaciju. Za to se koristi Dynamat ili AccuMat.

Svi moderni dizeli imaju plutajući zamajac radi ublažavanja vibracija i ostalih (uglavnom) gluposti. Dosta ljudi to prepravlja na obični zamajac, čitava industrija se razvila

kod plivajuceg zamajca su amortizacione mase puno vece nego li kod remenice, to je razlog kdanja zamajca.

Uobicajene izvodbe su sa oprugama i traju duze , dakle opruge iz lamele se sele u zamajac koji ima plivajuci elemenat vanjske potisne ploche.
Crkavaju na samom srcu, pri centru gde su sile najvece na veshanje 2 elementa u jedan.

Pravilo 1, nestiskati pun gas ispod 2300-2400 rpm na cetvrtacima.

1. Sta je pogonski puls?
1.a Sta je akseleracioni momenat klipa?
1.b Od chega zavisi?

2. Koliko stepeni radilice on traje?

Akceleracioni momenat je kad okine varnica pa se zapali corba pa klip krene da zalece na dole, traje 180* radilice tj dok ne dodje u dmt, jesam u pravu?

Maks akseleracija klipa je direktno po prelasku GMTa.
Vrlo je kratak i zavisi od geometrije motora, tj. duzina klipnjache prema hodu motora.
Motor koji ima malu prosecnu brzinu klipa ima visok akseleracioni momenat klipa i obratno.

Pogonski puls netraje 180 stepeni, DAJ BOZE , kako bi to bio efikasan motor
Traje max do ca:35-40 stepena u zoni akseleracije.
Geometrijski moze da traje (opet kazem geometrijski jer zavisi od duzine klipnjache vs hoda) u zavisnosti od ugla pod kojim klipnjacha napada radilicu te se dobija jedna promenljiva ugaona brzina.

Brzina sagorevanja koja zavisi od kompresije, goriva koje se koristi i tipa motora, tj resenja sfere sagorevanja utiche na oblik i duzinu pogonskog pulsa.
Sve razlike do 180 stepena kad sledeci cilindar napada su prepustene zamajcu.

Imamo li sad malo drugaciju sliku brzine okretanja radilice ?

Kod novijih diesela je geometrija motora izmenjena jer je ubrizgavanje postalo preciznije te se "tachka palnjenja" bolje definise.
Isto je ucinilo da je moguci akseleracioni momenat klipa povecan, znate i sami da se dieseli danas vrte u vece obrtaje nego li stari posto je bilo nemoguce varirati vreme ubrizgavanja prema obrtajima.

Sve te izmene geometrije sa visokim aks momentom klipa i jakim pogonskim pulsevima (Nm) dovode do vecih oscilacija brizne okreta radilice.

Prateci jednostavno frekvenciju sa senzora radilice vide se jasno oscilacije jer se frekvencija signala menja.
Na benzinskim motorima se moze solidno peglati i umirivati optimacijom paljenja u raznim uslovima rada motora, diesel jos uvek nema taj computing power te je izlozeniji havarijama na zamajcu tipa duple mase.

I za kraj jedno pitanje za Boost-a:
Cemu uopste plivajuci zamajac kada je lamela sa oprugama odradjivala isti posao? Odnosno sta se dobilo sa uvodjenjem zamajca (posto ja nikako nemogu da provalim evo i danas sam provozao ta dva auta)?



Oscilacije obrtanja spojnichk osovine, samim tim oscilacije supcanika menjaca su smanjene. Ranije su TD motori lomili menjache , danas lome zamajce (jeftinije - na zapadu uvek je Srbija izuzetak dok je Shabac u opticaju)

Za laganu voznju i niska opterecenja nije bitno u kojim si obrtajima.
No, zelis li ubrzati ostrije gledaj da pri saltanju padnes u sledeci stepen prenosa na ne ispod 2300 rpm.

To je sva filozofija.

Eb ga, ja sam sebi prekjuce ubio menjach, muka me bila da saltam i krenem da poteram jednog Audija 2,7T nesto chipovano od BSRa i pritisnem ga na 2000 rpm , 490Nm i paff, leva poluosovina se vrti na prazno unutar diferencijala nesto puklo
Da nisam bio lenj, da sam presalto nebi dobio tako agresivne pulseve bez blokade momenta jer po programu nemam blokadu momenta u 4-5 brzini.

Ima ga i na benzincima , stvar je da su otkrili da mogu da prave losije menjache koristeci plivajuce zamajce.

Zvekece kad izgubi moc apsorbacije .

Zasto je to problem izrazen samo za R4 motore? Ima li ga i na R6 i na V motorima? I, ako ne, zasto?



R4 - paljenje smjese svakih 90' radilice
R6 - paljenje smjese svakih 60'

Sto vise cilindara to su paljenje u cilusu (720') cesca. Drugim rijecima - manji udari na radilicu, tj. manje oscilacije. Kod diesela koji po defaultu rade na niskim rpm je to jos izrazenije.
Jesam li u pravu?

da

Na sve raspone snage, nova modna ludorija je zahvatila celu autoindustiju.

Umesto oblazivacha momenta u lameli (opruge) koje su pucale i podbadale se pod korpu chineci odvajanje lamele nemogucim i auto neupotrebljivim za vecinu obicnih korisnika, sve se prenelo na zamajac koji sad ima funkciju ublazivaca momenta. Inertna masa lamele prema inertoj masi plivajuceg dela zamajca je neuporediva te odatle i da je ublazivanje vibracija puno bolje na ulaznoj osovini menjacha (spojnickoj osovini) ali pod cenu da zamajci stradaju ali auto ostaje upotrebljiv duzi period od kad se greska prikaze.

Sa druge strane , pucanje korpe kvacila ili njene deformacije su izrazenija greska ovih konstrukcija jer je sama korpa puno manje mase nego li na standardnim zamajcima.

Drugom reci, izmena je i na dobro i na lose.
Kako god se okrenes, dupe uvek pozadi.

Ne mora da znaci da nece nikad da se pokvari ali se vjerovatnoca smanjuje