Seal structure for spool-type switching valve, and said spool-type switching valve

Patent metadata

Field	Value
Publication number	US-12025228-B2
Application number	US-201917262473-A
Country	US
Kind code	B2
Filing date	Jul 11, 2019
Priority date	Aug 2, 2018
Publication date	Jul 2, 2024
Grant date	Jul 2, 2024

Abstract

A sealing structure is configured in the following manner. When a packing having a pair of sealing portions formed at opposite edge portions of the outer peripheral surface thereof is installed in a land portion of a spool, the outside diameter of the packing is made smaller than the diameter of a slide surface of a spool hole. In a state in which the outer periphery of the land portion opposes the slide surface and a pressurized fluid is supplied from a gas supply channel to the first space of first and second spaces that are partitioned by the land portion, the edge portion of the packing positioned near the first space is elastically elongated in a radial direction due to pressure of the pressurized fluid and thereby narrows a gap formed between the first sealing portion and the slide surface of the spool hole or abuts the slide surface.

First claim

The invention claimed is:

1. A seal structure for a spool-type switching valve, wherein
the switching valve includes
a spool hole that is formed so as to extend in an axis direction and is in communication with a gas supply channel, an output channel, and a gas discharge channel,
a spool inserted in the spool hole and slidable in the axis direction, and
a valve actuation unit that moves the spool so as to switch a connection state of the channels,

the spool includes land portions and annular recesses that are disposed alternately in the axis direction, the land portions having respective sliding portions formed on outer peripheries thereof, the annular recesses having outside diameters smaller than outside diameters of the land portions,
the spool hole is defined by an inner peripheral surface formed annularly around the axis, and annular channel recesses and annular slide surfaces are formed at the inner peripheral surface alternately in the axis direction, the channel recesses being recessed respectively in the inner peripheral surface at positions of the gas supply channel, the output channel, and the gas discharge channel and being connected to the channels, the land portions of the spool being slidable with the sliding portions opposing respective slide surfaces of the spool hole,
an annular groove is formed in the sliding portion of each land portion so as to annularly surround the axis and so as to open in a radial direction, an inner end portion of a packing that includes an inner periphery of the packing is accommodated in the groove, and an outer end portion of the packing that includes an outer periphery of the packing protrudes from an opening edge of the groove, the packing being made of an elastic rubber member,
the outer end portion of the packing includes a first sealing portion annularly surrounded at one edge portion in the axis direction and a second sealing portion annularly surrounded at an other edge portion in the axis direction,
a maximum outside diameter on an outer periphery of the packing accommodated in the groove is formed so as to be smaller than a minimum inside diameter on the slide surface of the spool hole in a state in which a pressurized fluid is not supplied from the gas supply channel, and
in a state in which the sliding portion of each land portion opposes the corresponding slide surface of the spool hole and a pressurized fluid is supplied from the gas supply channel to one of a pair of spaces in the spool hole partitioned by each land portion, the edge portion of the packing positioned near the space to which the pressurized fluid is supplied is elastically elongated in the radial direction due to pressure of the pressurized fluid, and one of the first sealing portion and the second sealing portion, which is positioned near the space to which the pressurized fluid is supplied, narrows a gap formed between the sliding portion and the corresponding slide surface of the spool hole or abuts the corresponding slide surface.

2. The seal structure according to claim 1 , wherein
cross sections of the packing and the groove taken in the axis direction are in bilateral symmetry in the axis direction,
the groove is defined by a bottom wall surface that the inner end of the packing abuts and also by a pair of side wall surfaces that rise in the radial direction from opposite ends, in the axis direction, of the bottom wall surface so as to oppose each other, and
in the radial direction, a depth of the groove from the bottom wall surface to the opening edge thereof is made larger than a half of a height of the packing from the inner end to the outer end thereof.

3. The seal structure according to claim 2 , wherein
the bottom wall surface intersects a pair of the side wall surfaces at an angle of 90 degrees or less in the groove.

4. The seal structure according to claim 3 , wherein
in the axis direction, a maximum width of the inner end portion of the packing that is accommodated in the groove is made smaller than a minimum width of the groove between a pair of the side wall surfaces.

5. The seal structure according to claim 4 , wherein
the inner end of the packing is fixed by an adhesive to the bottom wall surface of the groove.

6. The seal structure according to claim 1 , wherein
the packing includes a pair of side surfaces that are positioned opposite to each other in the axis direction and that extend parallel to each other so as to face opposite directions to each other, and a cross section of the packing taken in the axis direction is in bilateral symmetry in the axis direction,
the outer end portion of the packing includes an outer end surface that opposes the corresponding slide surface, and
the first sealing portion is formed at one edge portion of the outer end surface, and the second sealing portion is formed at the other edge portion of the outer end surface, the one edge position being positioned opposite to the other edge portion in the axis direction.

7. The seal structure according to claim 6 , wherein
the first sealing portion is a first protrusion that protrudes from the outer end surface in the radial direction, and the second sealing portion is a second protrusion that protrudes from the outer end surface in the radial direction.

8. The seal structure according to claim 7 , wherein
in the radial direction, distances between the corresponding slide surface and tips of the first protrusion and the second protrusion are the same.

9. The seal structure according to claim 8 , wherein
the outer end surface of the packing is formed so as to be parallel to the corresponding slide surface,
heights of the tips of the first protrusion and the second protrusion from the outer end surface are the same, and
the first protrusion and the second protrusion are spaced from each other in the axis direction.

10. The seal structure according to claim 9 , wherein
the first protrusion and the second protrusion are shaped like wedges with respective widths in the axis direction decreasing from the outer end surface toward the tips.

11. The seal structure according to claim 9 , wherein
a labyrinth protrusion for forming a labyrinth seal is formed on the outer end surface of the packing at a position between the first protrusion and the second protrusion.

12. The seal structure according to claim 6 , wherein
narrowing grooves are formed in respective side surfaces of the packing so as to annularly surround the axis and so as to be in communication with the opening of the groove.

13. The seal structure according to claim 12 , wherein
the narrowing grooves are formed of concave surfaces.

14. A spool-type switching valve comprising the seal structure according to claim 1 , wherein
the switching valve includes a housing in which the spool hole is formed, and
a gas supply port that forms a gas supply channel and is connected to a pressurized fluid source to supply a pressurized fluid, an output port that forms an output channel and outputs the pressurized fluid from the pressurized fluid source to an external pressurized fluid device, and a gas discharge port that forms a gas discharge channel and discharges exhaust gas from the pressurized fluid device are formed at outer surfaces of the housing.

Assignees

• Smc Corp

Inventors

• Miyazoe Shinji
• Noguchi Kazuhiro
• Umeda Kazuhiro
• Kudo Masayuki
• Kawakami Masahiko

Classifications

• F16K11/07

  with cylindrical slides · CPC title

• F16J15/441

  with floating ring · CPC title

• F16J15/447

  Labyrinth packings · CPC title

• F16J15/44

  Free-space packings · CPC title

• F16J15/56

  Other sealings for reciprocating rods · CPC title