Variable pressure relief and control valve

A variable pressure relief valve for relieving pressures in a fluid line comprising:

• a. a valve body;
• b. an inlet passage on said valve body connectable to a fluid line to be valved;
• c. a relief passage on said valve body;
• d. a valve seat interposed between said inlet and said outlet passages at generally the intersection of the inlet passage axis and the outlet passage axis;
• e. a varying member movably mounted within said valve body for movement into and out of sealing engagement with said valve seat;
• f. a valve stem attached at one end portion to said valving member and extending therefrom externally of said valve body;
• g. a valve actuator housing bonnet attached to said valve body on generally the same axis as said valve inlet, said stem extending into said actuator housing a distance;
• h. a connecting flange member means placed laterally across said valve actuator housing for forming a connection between said valve body and said actuator housing bonnet, said flange member means providing an opening through which said valve stem protrudes from said valve body into said actuator housing bonnet;
• i. a base plate member attached to said valve stem and moving therewith responsive to opening and closing of said valving member upon said valve seat;
• j. a plurality of coil springs having at their central axis said valve stem and registering at one end portion with said base plate member, said coil springs extending longitudinally into said actuator housing bonnet different linear distances;
• k. a pressure plate movably mounted within said valve housing generally opposite said base plate, with said coil springs being placed within said housing bonnet generally between said base plate and said pressure plate;
• l. a threaded shaft placed through said housing bonnet opposite said base plate and attaching at one end portion to said pressure plate, rotation of said shaft affecting a linear movement of said pressure plate with respect to both said housing bonnet and said base plate to variably compress or decompress said springs therebetween;
• m. means for imparting rotational energy to said shaft;
• and
• n. sear means independent of said coil springs and carried by said housing bonnet for imparting a frictional retention to said base plate member at least prior to opening and prior to closing of said seat by said valving member.