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A check valve comprises: a pair of cylindrical body elements (1, 4) through which a fluid passes; a cylindrical valve element (7), which is disposed inside an upstream-side one (4) of the cylindrical body elements (1, 4), constantly subjected to a fluid pressure and biased toward its closed position

A check valve comprises: a pair of cylindrical body elements (1, 4) through which a fluid passes; a cylindrical valve element (7), which is disposed inside an upstream-side one (4) of the cylindrical body elements (1, 4), constantly subjected to a fluid pressure and biased toward its closed position under the influence of a resilient force exerted by a compression coil spring (10) coated with a tubular element; and, a stopper element (24) disposed in a downstream-side one (4) of the cylindrical body elements (1, 4). The check valve is characterized in that at least one of the cylindrical valve element (7) and the stopper element (24) is provided with a spiral seat portion (11) an axial spiral surface of which is brought into stable surface-contact with the compression coil spring (10) to support the compression coil spring (10) therein.

대표청구항 ▼

1. A check valve comprising: a pair of body elements (1, 4) through which a fluid passes; a cylindrical valve element (7), which is slidably engaged inside one (1) of said pair of body element (1, 4), constantly subjected to a fluid pressure and biased toward its closed position under the influence

1. A check valve comprising: a pair of body elements (1, 4) through which a fluid passes; a cylindrical valve element (7), which is slidably engaged inside one (1) of said pair of body element (1, 4), constantly subjected to a fluid pressure and biased toward its closed position under the influence of a resilient force exerted by a compression coil spring (10) having a diameter substantially equal to an inside diameter of a recess within the cylindrical valve element in which the compress on coil spring is engaged, said compression coil spring coated with a tubular element; and, a stopper element (24) disposed inside another one (4) of said pair of body elements (1, 4), wherein at least one of said cylindrical valve element (7) or said stopper element (24) is provided with a spiral seat portion (11) having a spiral surface which is brought into press-contact with a terminal turn of said compression coil spring (10) to support said compression coil spring (10) in said cylindrical valve element (7), and wherein said compression coil spring (10) is constrained to move within said pair of body elements only in the direction of the longitudinal axis of the check valve without fear of buckling.2. The check valve as set forth in claim 1, wherein each of said cylindrical valve element (7) and said stopper element (24) is provided with said spiral seat portion (11).3. The check valve as set forth in claim 1, wherein said spiral seat portion (11) is integrally formed with each of said cylindrical valve element (7) and said stopper element (24).4. The check valve as set forth in claim 1, wherein said spiral seat portion (11) of each of said cylindrical valve element (7) and said stopper element (24) is separate in construction from each of said cylindrical valve element (7) and said stopper element (24) so as to form a separate element.5. The check valve as set forth in claim 1, wherein said spiral surface of said spiral seat portion (11) of each of said cylindrical valve element (7) and said stopper element (24) is brought into press-contact with one of opposite terminal turns of said compression coil spring (10).6. The check valve a set forth in claim 5, wherein said spiral surface of said spiral seat portion (11) of each of said cylindrical valve element (7) and said stopper element (24) has a concave recess all of which is respectively engaged against each of said opposite terminal turns and faces in the direction of the longitudinal axis of the check valve.7. The check valve as set forth in claim 6, wherein said recess of said spiral surface of said spiral seat portion (11) of each of said cylindrical valve element (7) and said stopper element (24) has a semi-circular concave shape in cross section.8. The check valve as set forth in claim 1, wherein an O-ring (8) is mounted in an innermost portion of the one (1) of said body elements (1, 4), said O-ring (8) brought into press-contact with a head portion of said cylindrical valve element (7) when said cylindrical valve element (7) is in a close position to prevent the fluid from passing through an area between said O-ring (8) and said head portion of said cylindrical valve element (7).9. The check valve a set forth in claim 8, wherein said head portion of said cylindrical valve element (7) has its outer peripheral surface curved to form a curved outer peripheral surface portion which is brought into press-contact with said O-ring (8) when said cylindrical valve element (7) is in the closed position to prevent the fluid from passing through said area between said O-ring (8) and said head portion of said cylindrical valve element (7).10. The check valve as set forth in claim 1, wherein: said body elements (1, 4) comprise an upstream-side body element (1) and a downstream-side body element (4) a portion of which is threadably mounted in said upstream-side body element (1); and, said downstream-side body element (4) comprises said stopper element (24).11. The check valve as set forth in claim 1, wherein: said tubular element of said compression coil spring (8) is made of fluororesins.12. A check valve comprising: a pair of body elements (1, 4) threadingly engaged together and through which a fluid passes; a cylindrical valve element (7), which is slidably engaged inside one (1) of said pair of body elements (1, 4), constantly subjected to a fluid pressure an biased toward its closed position under the influence of a resilient force exerted by a compression coil spring (10), said compression coil spring coated with a tubular element; and, a stopper element (24) disposed inside another one (4) of said pair of body elements (1, 4), wherein at least one of said cylindrical valve element (7) or said stopper element (24) is provided with a spiral seat portion (11) having a spiral surface facing in the direction of the longitudinal axis of the check valve, said spiral surface engaging a terminal turn of said compression coil spring (10) to support said compression coil spring (10) in said cylindrical valve element (7), and wherein said compression coil spring (10) said constrained to move within said pair of body elements in the direction of the longitudinal axis of the check valve without fear of buckling.13. The check valve as set forth in claim 12, wherein each of said cylindrical valve element (7) and said stopper element (24) is provided with said spiral seat portion (11).14. The check valve as set forth in claim 12, wherein said spiral seat portion (11) is integrally formed with each of said cylindrical valve element (7) and said stopper element (24).15. The check valve as set forth in claim 13, wherein said spiral seat portion (11) of each of said cylindrical valve element (7) and said stopper element (24) is separate in construction from each of said cylindrical valve element (7) and said stopper element (24) so as to from a separate element.16. The check valve as set forth in claim 12, wherein said spiral surface of said spiral seat portion (11) of each of said cylindrical valve element (7) and said stopper element (24) is brought into press-contact with one of opposite terminal turns of said compression coil spring (10).17. The check valve as set forth in claim 16, wherein said spiral surface of said spiral seat portion (11) of each of said cylindrical valve element (7) and said stopper element (24) has a concave recess all of which is engaged against each of said opposite terminal turns.18. The check valve as set forth in claim 17, wherein said recess of said spiral surface of said spiral seat portion (11) of each of said cylindrical valve element (7) and said stopper element (24) has a semi-circular concave shape in cross section.19. The check valve as set forth in claim 12, wherein an O-ring (8) is mounted in an innermost portion of the one (1) of said body elements (1, 4), said O-ring (8) brought into press-contact with a head portion of said cylindrical valve element (7) when said cylindrical valve element (7) is in a closed position to prevent the fluid from passing through an area between said O-ring (8) and said head portion of said cylindrical valve element (7).20. The check valve as set forth in claim 19, wherein said head portion of said cylindrical valve element (7) has its outer peripheral surface curved to form a curved outer peripheral surface portion which is brought into press-contact with said O-ring (8) when said cylindrical valve element (7) is in the closed position to prevent the fluid from passing through said area between said O-ring (8) and said head portion of said cylindrical valve element (7).