| 摘要 |
<p>A piston and cylinder valve is described in which two identical pistons act within the same cylinder. A torque motor is provided with a finger which extends into the cylinder approximately in the center thereof. The two pistons are urged by springs toward each other and into engagement with opposite sides of the finger. By this simple arrangement, coupling between the torque motor and the pistons is achieved with neither backlash nor danger of binding. Additionally, provision is made for adjusting the neutral or reference position of the valve and also for adjusting the amount of dead space. According to one embodiment, two sleeves are provided, one for each piston, and are made with different diameter portions so as to be urged apart by fluid pressure and into engagement with position limiting screws. Adjustment of these screws adjusts the cut off positions of passageways in the sleeves with respect to the lands of the pistons. In accordance with another embodiment, no sleeves are required but adjacent ends of each piston are provided with adjusting screws by with the position of each piston relative to the actuating arm of the torque motor can be adjusted thereby adjusting the position of the cut-off edge of the lands with respect to the passageways in the valve body.</p> |
