| 摘要 |
<p>A self wear compensating valve for controlling flow of a fluid employs seals for sealing between relatively moving parts. In one of the parts, an annular recess is formed. A conformable sealing member is placed in the recess, and a spring biased to expel the conformable sealing member and press it against a sealing surface on the other part is provided. An O-ring placed on the outside of the conformable sealing member prevents leakage of fluid through the recess outside of the conformable sealing member. As the conformable sealing member is worn away, after many cycles of the valve, the spring continues to press it against the sealing surface, while the O-ring continues to prevent leakage of fluid outside the conformable sealing member. A rotary valve suitable for railroad brake applications is provided, which controls flow of fluid from a supply to the brake cylinder, and provides for exhaust of fluid from the brake cylinder. The valve has a supply port, a delivery port and an exhaust. In one position, the supply port is connected to the delivery port through a passage in the rotor. In another position, the delivery port is connected to the exhaust port through a passage in the rotor. In a third position, the lap position, all the ports are blocked by the relative position of the rotor and the housing. Proportional control of fluid flow is provided by elongating the ports on the mating surfaces of the rotor and the housing in the direction of rotation. <IMAGE></p> |
