Patent Application
20080087339
Referring to the drawing, a direct acting hydraulic voting trip block comprises a valve block 10 having three valves 12, 14, 16 cylinders therein. Three valve pistons 18, 20, 22 are located in the valve cylinders. Three springs 24, 26, 28 bias the valve pistons in the non-activated position. Three electric solenoid actuators 30, 32, 34 are provided for moving the pistons against the bias of the springs into an activated position. Typically, the solenoid actuators move the piston into an activated position when receiving a non-fault condition signal. The valve block defines three separate paths 36, 38, 40 between an inlet port 42 and an outlet port 44. Each path intersects the three valve cylinders. Each valve piston is configured to, in the activated position, block two of the three paths. Each valve piston is configured to close a different two of the three paths. Thus, as long as at least two of the pistons are in the activated position, communication between the inlet and outlet ports is prevented. Normally, the inlet port is in communication with a normally pressurized control port.
The voting trip block is provided with three valve piston position monitors 46, 48, 50, one associated with each valve piston. Thus, a solenoid can be commanded to deactivate and the response of the corresponding position monitor observed to determine the associated solenoid, valve piston, and position monitor are in good running order without allowing communication between the inlet and outlet ports.
As shown in the drawing, each piston 18, 20, 22 extends axially between a solenoid actuator and a bias spring. Each piston has two enlarged diameter blocking sections 52, 54 for closing two paths when in the activated position and two smaller diameter unblocking sections 56, 58 adjacent the blocking portion for opening the two paths and a third elongated unblocking section 60 for unblocking the third path in either the activated or non-activated position.
As shown in the drawing of the preferred embodiment, the three valve cylinders have parallel and spaced axes. The three paths between the inlet and outlet ports have portions intersecting the valve cylinders which have parallel and spaced axes. The axes of the valve cylinders and the paths between the inlet and outlet ports are perpendicular. The bias springs and solenoids are at the opposite axial end of the valve cylinders. The solenoids are aligned on one face of the valve block.
Having thus defined our invention in the detail and particularity required by the Patent Laws, what is desired protected by Letters Patent is set forth in the following claims.
