Patent ID: 6349742
Filing Date: 2002-02-26
Classification: F16K,Y10T

Abstract:
A dual-seat valve that switches in a leak-free manner, including:a valve housing part (1) having at least two openings for two lines for letting fluid in and out, two coaxial valve seats (2, 3) disposed between these openings, two valve closing members (7, 9) that are each guided in the valve housing part (1) between an open position and a closing position for coaxial motion relative to one another and to the corresponding valve seats (2, 30) and which in their closing position effect double sealing between said openings, the first closing member being a slide piston (7) with radial sealing means (12) disposed on an end portion of said slide piston, said piston pressing, during an opening motion, against the second closing member (9) and during the continued opening motion moving the second closing member (9) into its open position as well, the first valve seat (2) being cylindrical and in the closing position receiving the slide piston (7) in sealing fashion, and both in the closing position and in the open position a leakage chamber is formed between the closing members, which communicates permanently with the outside of the valve via a drain outlet (25), characterized in that a cylindrical inside face (5) is provided at the second valve seat (3), and a cylindrical portion (20) corresponding to said cylindrical inside face (5) is provided on the second closing member (9), the diameter of which portion is less than the diameter of the cylindrical inside face (5) of the second valve seat (3), and the cylindrical face (5, 20), both in a cleaning stroke and the closing and opening motion of the second closing member (9), form a throttle gap (26) between them, the second valve seat (3) having a conical portion (6) extending from the cylindrical inside face (5) of the second valve seat (3) to the first valve seat (2), and that a sealing means (17) is provided on the second closing member (9) in such a way that in the closing motion, the throttle gap (26) is formed first, before the sealing means (17) seals off the leakage chamber from the line.