Water hammer preventing check valve

• US 5,746,246 A
• Filed: 05/19/1997
• Issued: 05/05/1998
• Est. Priority Date: 12/05/1994
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Yokota Seisakusho
• Original Assignee: Hiroshi Yokota, Kabushiki Kaisha Yokota Seisakusho, Shingo Yokota
• Inventors: Yokota, Shingo, Yokota, Hiroshi
• Primary Examiner(s): Ferensic, Denise L.
• Assistant Examiner(s): Kim, Joanne Y.
• Application Number:
  US08/836,795
• Time in Patent Office: 351 Days
• Field of Search: 137/527.4, 137/527, 137/514, 251/87, 251/84
• US Class Current: 137/514
• CPC Class Codes: F16K 15/033 spring-loaded
• CPC Class Codes: F16K 47/0111 the valve members comprising a plunger sliding within a fixed dashpot
• CPC Class Codes: F16K 47/023 for preventing water-hammer, e.g. damping of the valve movement
• CPC Class Codes: Y10T 137/785 With retarder or dashpot
• CPC Class Codes: Y10T 137/7898 Pivoted valves

Abstract

A check valve for preventing water hammer in which a valve element is adapted for quick initiation of a valve closing motion without delay in response to an abrupt change in fluid flow resulting from stoppage of a pump, and which is seated on a valve seat when the inertial flow of the fluid in the discharge direction stops, without generating a water hammer and impulse noise. The valve element and the valve seat are constructed so that the valve element follows the motion of the flowing fluid and is interlocked with a braking device by a linear motion transmitting mechanism. The linear motion transmitting mechanism and the braking device are constructed to remove the effect of braking actions that decelerate the valve closing motion of the valve element and of frictional resistance in the period between when the valve element starts a valve closing motion and when the valve element is almost seated on the valve seat, and then to brake the valve element gently only until the valve element is seated on the valve seat. The timing of the seating of the valve element on the valve seat can be adjusted by a mechanism for adjusting the braking action starting position, by a bypass adjusting valve combined with the braking device or by a mechanism for adjusting biasing force applied to the valve element.

Claims

1. A water hammer preventing check valve comprising:

a valve casing (1);

a valve seat (3) disposed within the casing (1) at an inclination to streamlines of a fluid flowing through a passage in the casing (1); and

a monoplane valve element (4) supported for swing motion within the valve casing (1) so as to be open to discharge the fluid while a pump is in operation and to be closed to check the reverse flow of the fluid on the discharge side when the pump stops;

wherein the valve element (4) is always urged to swing in a valve closing direction, is formed in a shape which exerts a low form drag and a low inertial resistance, and is constructed so as to be substantially seated on the valve seat (3) at a moment when the inertial flow of the fluid in a discharge direction stops;

a braking device (13) is attached to an upper portion of the valve casing (1);

the valve element (4) is connected at a position on its back surface on the discharge side to a linear motion transmitting mechanism through a linking mechanism which does not transmit any motion while the valve element (4) is in a moving range other than a limited moving range between a position where the valve element (4) is almost seated on the valve seat (3) and a position where the valve element (4) is seated on the valve seat (3);

the linear motion transmitting mechanism is connected to the braking device (13) so that the braking device (13) does not decelerate the valve closing motion until the valve element (4) in the valve closing motion reaches the position where the valve element (4) is almost seated on the valve seat (3), and the braking device (13) exerts a pulling force on the valve element (4) only while the valve element (4) moves in the limited moving range between the position where the valve element (4) is almost seated on the valve seat (3) and the position where the valve element (4) is seated on the valve seat (3).

3. The water hammer preventing check valve according to claim 1, wherein the timing of seating the valve element (4) on the valve seat (3) is adjusted by means of a braking action starting position adjusting mechanism (16), a bypass adjusting valve (18) combined with the braking device (13) or a biasing force adjusting mechanism (20) for adjusting the valve element biasing force of a valve element biasing member (19).

2. A water hammer preventing check valve comprising:

a valve casing (1);

a valve seat (3) disposed within the casing (1) at an inclination to streamlines of a fluid flowing through a passage in the casing (1); and

a monoplane valve element (4) supported for swing motion within the valve casing (1) so as to be open to discharge the fluid while a pump is in operation and to be closed to check the reverse flow of the fluid on the discharge side when the pump stops;

wherein the valve element (4) is always urged to swing in a valve closing direction, is formed in a shape which exerts a low form drag and a low inertial resistance, and is constructed so as to be substantially seated on the valve seat (3) at a moment when the inertial flow of the fluid in a discharge direction stops;

a braking device (13) is attached to an upper portion of the valve casing (1);

the valve element (4) is connected at a position on its back surface on the discharge side directly to the braking device (13) through a linear motion transmitting mechanism;

the braking device (13) is constructed so as not to exercise any braking effect while the valve element (4) is in a moving range other than a limited moving range between a position where the valve element (4) is almost seated on the valve seat (3) and a position where the valve element (4) is seated on the valve seat (3);

the valve element (4) is biased in a valve closing direction by a valve element biasing member (19) which exerts a valve element biasing force exceeding frictional resistances of moving members and sealing members associated with the braking device (13) in order that the valve element (4) is not decelerated during a valve closing motion by the braking device (13) until the valve element (4) reaches the position where the valve element (4) is almost seated on the valve seat (3) and the braking device (13) exerts a pulling force on the valve element (4) only while the valve element (4) moves in the valve closing direction in the limited moving range between the position where the valve element (4) is almost seated on the valve seat (3) and the position where the valve element (4) is seated on the valve seat (3).

4. The water hammer preventing check valve according to claim 2, wherein the timing of seating the valve element (4) on the valve seat (3) is adjusted by means of a braking action starting position adjusting mechanism (16), a bypass adjusting valve (18) combined with the braking device (13) or a biasing force adjusting mechanism (20) for adjusting the valve element biasing force of a valve element biasing member (19).