| 摘要 |
An anti-coking bushing assembly for sealing a pintle shaft of an EGR control valve, comprising a bushing carrier disposed in the valve body and supportive of close-fitting pintle shaft bushing liners formed of a polyimide such as Vespel. The bushing carrier and bushing liners are installed into a carbon shield extending into the exhaust flow space within the valve. Within the carbon shield, between the gas flow space and the bushing carrier, is a ring seal on the pintle shaft and a gas expansion chamber to cool exhaust gas escaping along the pintle shaft, allowing contaminants in the exhaust gas to precipitate in the gas expansion chamber. The carbon shield, ring seal, bushing carrier, and bushing liners are conveniently pre-assembled as an anti-coking bushing assembly for subsequent installation into a valve body during final valve assembly.
|
