Trunnion-type ball valve, valve seal structure, and valve packing

Patent metadata

Field	Value
Publication number	US-10767768-B2
Application number	US-201615571362-A
Country	US
Kind code	B2
Filing date	May 13, 2016
Priority date	May 13, 2015
Publication date	Sep 8, 2020
Grant date	Sep 8, 2020

Abstract

A trunnion-type ball valve, a valve seal structure, and a valve packing in which, a seal surface pressure of a tip outer peripheral region is improved. A ball ( 3 ) provided inside a body ( 2 ) is rotatably provided via upper and lower stems ( 4 and 5 ) and is sealed with a ball seat ( 6 ). The trunnion-type ball valve has a packing attached between an outer periphery step part provided at a rear part of the ball seat and the body and a pressing mechanism by which the packing is pressed to a ball direction, and is provided with a contact surface to be contacted with a step part surface of the outer periphery step part on a tip outer diameter side of the packing and a space provided between the packing and the step part surface of the outer periphery step part on a tip inner diameter side of the packing.

First claim

The invention claimed is:

1. A trunnion-type ball valve comprising:
a body;
a ball provided rotatably inside the body via upper and lower stems;
a ball seat pressed into contact with the ball to form a seal;
a packing disposed between an outer periphery step part provided at a rear part of the ball seat and the body; and
a pressing mechanism including a spring and a retainer gland pressed by a resilient force of the spring,
the packing being provided with a contact surface contacting a step part surface of the outer periphery step part, the contact surface being on a tip outer diameter side of a tip surface of the packing, and
the packing being provided with a non-contact part, and a space is defined between the non-contact part and the step part surface of the outer periphery step part.
the non-contact part being on a tip inner diameter side of the tip surface of the packing, and
the tip surface of the packing including the contact surface and the non-contact part of the packing,
wherein, when a rear end part of the packing is pressed by the retainer gland, an inner diameter side of the packing advances into the space more than an outer diameter side of the packing, and a torsional action occurs between the inner diameter side and the outer diameter side of the packing with:
an inner diameter side of the rear end part of the packing functioning as a point of effort:
the contact surface of the packing functioning as a fulcrum; and
a tip outer peripheral region of the packing functioning as a point of load.

2. The trunnion-type ball valve according to claim 1 , wherein the packing has a friction resistance on an inner peripheral side smaller than a friction resistance on an outer peripheral side, such that when the packing is pressed, an inner diameter side of the packing advances more than an outer diameter side of the packing and the torsional action occurs on the packing, with the contact surface functioning as a fulcrum, to increase the seal surface pressure of the tip outer peripheral region serving as a point of load.

3. The trunnion-type ball valve according to claim 1 , wherein a non-contact part defining the space is a tapered surface oriented to face the tip inner diameter side of the packing, and the tapered surface is gradually brought into contact with the step part surface of the ball seat from an outer diameter side by the pressing force of the pressing mechanism and a force caused by fluid pressure.

4. The trunnion-type ball valve according to claim 1 , wherein a non-contact part defining the space is formed of a notched groove provided in the step part surface of the ball seat.

5. The trunnion-type ball valve according to claim 1 , wherein the retainer gland has an annular protruding part pressed against the rear end part of the packing, and the annular protruding part is formed on a tip side of the retainer gland.

6. The trunnion-type ball valve according to claim 1 , wherein the packing is a molded packing having laminated expanded-graphite-made sheets.

7. The trunnion-type ball valve according to claim 1 , wherein a rear end part of the packing is formed to have a concave, substantially V-shaped cross section, and the packing rear end part is sealed in a state of being pushed and spread to each of a ball seat side and a body side by pressing of the pressing mechanism.

8. The trunnion-type ball valve according to claim 7 , wherein the concave,. substantially V-shaped, cross section of the rear end part of the packing is provided so as to form an angle, and the rear end part has a thickness provided to be substantially uniform to a tail end side.

9. The trunnion-type ball valve according to claim 7 , wherein inner and outer peripheral surfaces of the packing are formed as tilted surfaces tilted relative to an axial direction of the packing, and a seal surface pressure of inner and outer peripheral portions of the rear end part of the packing is raised in a state in which a rear end side of the packing on inner and outer peripheral sides protrude to either or both of the ball seat side and the body side.

10. A valve seal structure comprising:
a seat adapted to contact, in a pressed state, a valve body attached inside a body via a stem so as to be freely opened and closed:
a packing disposed between an outer periphery step part provided at a rear part of the seat and the body; and
a pressing mechanism by which the packing is pressed towards a valve body, the pressing mechanism including a spring and a retainer gland pressed by a resilient force of the spring,
the packing being provided with a contact surface for making contact with a step part surface of the outer periphery step part on a tip outer diameter side of the packing, and a non-contact part defining a space between the packing and the step part surface of the outer periphery step part on a tip inner diameter side of a packing tip surface other than the contact surface, and
wherein, when a rear end part of the packing is pressed by the retainer gland, an inner diameter side of the packing advances into the space further than an outer diameter side of the packing, and a torsional action occurs between the inner diameter side and the outer diameter side of the packing with:
an inner diameter side of the rear end part of the packing functioning as a point of effort:
the contact surface of the packing functioning as a fulcrum; and
a tip outer peripheral region of the packing functioning as a point of load.

11. The valve seal structure according to claim 10 , wherein the packing has a friction resistance on an inner peripheral side smaller than a friction resistance on an outer peripheral side, when the packing is pressed, an inner diameter side of the packing advances more than an outer diameter side of the packing and sealing is made in a state in which a torsional action is caused to occur on the packing, with the contact surface functioning as a fulcrum, to increase a surface pressure of the tip outer peripheral region serving as a point of load.

12. A valve packing capable of sealing when attached to a space between a rear part of a seat in a pressed state to be contacted with a valve body attached inside a body of a valve via a stem so as to be freely opened and closed and the body, the valve packing comprising:
a contact surface for making contact with a step part surface of an outer periphery step part of the seat is provided on a tip outer diameter side of the packing; and
a non-contact part that does not make contact with the seat is provided on a tip inner diameter side of a packing tip surface other than the contact surface.
wherein, when a rear end part of the packing is pressed by a pressing force of a pressing mechanism, an inner diameter side of the packing will advance in a direction toward the seat more than an outer diameter side of the packing, and a torsional action occurs between the inner diameter side and the outer diameter side of the packing with:
an inner diameter side of the rear end part of the packing functioning as a point of effort:
the contact surface of the packing functioning as a fulcrum; and
a tip outer peripheral region of the packing functioning as a point of load.

13. The valve packing according to claim 12 , wherein the non-contact part is a tapered surface that is tapered toward the tip inner diameter side.

14. The valve packing according to claim 12 , wherein inner and outer peripheral surfaces are formed as tilted surfaces that are tilted in an axial direction of the packing, and one or both of the inner and outer peripheral sides of the rear end part protrude so as to raise a seal surface pressure

Assignees

• Kitz Corp

Inventors

• Kazama Masahiro
• Funato Masazumi

Classifications

• F16K5/0647

  Spindles or actuating means · CPC title

• F16K5/20

  for plugs with spherical surfaces · CPC title

• F16K5/0605

  with particular plug arrangements, e.g. particular shape or built-in means · CPC title

• F16K5/0689 Primary

  between housing and plug · CPC title

• F16K5/201

  with the housing or parts of the housing mechanically pressing the seal against the plug · CPC title