Bellows balanced valve

A bellows valve assembly comprising:

• a valve body having an inlet, an outlet, a valve bore positioned between said inlet and said outlet, and a valve seat disposed between said inlet and said outlet;
• a housing positioned adjacent said valve body and defining a bellows balancing chamber;
• a valve closure element having a sealing surface positioned in said valve bore and engageable with said valve seat to restrict fluid flow through said valve bore, and a valve stem extending from said sealing surface through said bellows housing;
• a pressure-balanced bellows assembly having at least one section secured to said valve stem, said bellows assembly being spaced from surrounding a portion of said valve stem to divide said bellows balancing chamber into a first chamber defined inside of said bellows assembly and a second chamber defined outside of said bellows assembly between said valve stem and said bellows assembly, wherein said first chamber is in communication with a fluid pressure downstream of said valve seat and said second chamber is in communication with a fluid pressure upstream of said valve seat and wherein said valve stem has a lower portion characterized by a first average diameter, and an upper portion characterized by a second average diameter and engageable with said actuator, said second average diameter being substantially smaller than said first average diameter;
• and
• an actuator disposed on a side of said housing opposite said valve body, said actuator being engageable with said valve stem to move said sealing surface relative to said valve seat.

An exhaust gas recirculation valve assembly comprising:

• a valve body having an inlet, an outlet, a valve bore positioned between said inlet and said outlet, and a valve seat disposed between said inlet and said outlet;
• a housing positioned adjacent said valve body and defining a bellows balancing chamber therein;
• a valve closure element having a sealing surface positioned in said valve bore and engageable with said valve seat to restrict fluid flow through said valve cavity, and
• a valve stem having a lower portion extending from said valve sealing surface into said bellows balancing chamber and an upper portion extending from said lower portion, wherein said upper portion is characterized by an average diameter that is at least about 25% smaller than an average diameter of said lower portion;
• a pressure-balanced bellows assembly having an end section fixed to said lower portion of said valve stem, said bellows assembly being positioned in said bellows housing to surround a portion of said lower portion, wherein said bellows assembly divides said balancing chamber into a first chamber defined between said bellows assembly and said lower portion and a second chamber defined outside said bellows assembly;
• an actuator positioned on a side of said housing opposite said valve body, said actuator being engageable with said upper portion of said valve stem to move said sealing surface relative to said valve seat;
• a first passageway communicating said first chamber with a fluid pressure downstream of said valve seat;
• and
• a second passageway communicating said second chamber with a fluid pressure upstream of said valve seat.