This section provides background information related to the present disclosure which is not necessarily prior art.
Solenoid operated valves are known which provide control of a fluid such as pressurized air for use in operating equipment such as sorters, packaging machines, food processors, and the like. In order to retain the solenoid operated valve in a closed position, biasing members such as springs are known.
It is also known, for example, in U.S. Pat. No. 4,598,736 to Chorkey that an inlet pressure of the pressurized fluid can be balanced within the valve to reduce the force required by the solenoid assembly to move a valve member between closed and open positions. Known pressure balanced valve designs have several drawbacks which can include valve seals such as O-rings or D-rings in end pistons of the valve members which provide a moving seal to allow valve member sliding motion, which is also dependent on a surface finish of the bore receiving the D-ring. These seals, however, are susceptible to atmospheric contaminants entering the valve due to seal wear or when equalizing pressure to allow piston movement, and are also susceptible to creep when the valve is pressurized, which increases break-away friction and therefore lengthens valve opening time. Moisture and dirt as contaminants in the valve assembly can enter the solenoid assembly which can result in valve sticking, reduced valve power, delayed operating times, damage to the bore surface finish resulting in D-ring damage, or leakage.