초록 ▼

A check valve includes a main-casing, a sub-casing, a positive-pressure valve and a negative-pressure valve. The positive-pressure valve has through holes and a negative-pressure valve seat. The negative-pressure valve has leg portions. A cap is disposed within the positive-pressure valve. A positiv

A check valve includes a main-casing, a sub-casing, a positive-pressure valve and a negative-pressure valve. The positive-pressure valve has through holes and a negative-pressure valve seat. The negative-pressure valve has leg portions. A cap is disposed within the positive-pressure valve. A positive-pressure spring is disposed between the positive-pressure valve and the sub-casing, and a negative-pressure spring is disposed between the positive-pressure valve and the cap. A positive-pressure flow path for releasing fuel vapor is formed between an outer circumference of the positive-pressure valve and an inner circumference of the main-casing, at further outward position than the positive-pressure spring. A negative-pressure flow path for introducing outside air is formed between an inner circumference of the positive-pressure valve and the leg portions and an outer circumference of the cap and between the through holes and the leg portions, at further outward position than the negative-pressure spring.

대표청구항 ▼

1. A check valve connected to a pipe communicating with an interior of a fuel tank, the check valve including a main-casing having a positive-pressure valve seat formed in an interior thereof, a sub-casing assembled to the main-casing so as to form a valve chamber and communicating with an outside o

1. A check valve connected to a pipe communicating with an interior of a fuel tank, the check valve including a main-casing having a positive-pressure valve seat formed in an interior thereof, a sub-casing assembled to the main-casing so as to form a valve chamber and communicating with an outside of the fuel tank, and a positive-pressure valve and a negative-pressure valve disposed slidably in the valve chamber, wherein the positive-pressure valve is formed into a cylindrical shape, a plurality of through holes communicating with an interior thereof and a negative-pressure valve seat to and from which the negative-pressure valve is attached and detached are formed on a distal end side of the positive-pressure valve, and an outer circumference of the positive-pressure valve is attached to and detached from the positive-pressure valve seat,wherein the negative-pressure valve is disposed on an outer side of a distal end of the positive-pressure valve so as to be attached to and detached from the negative-pressure valve seat to thereby close and open the through holes and has a plurality of leg portions which are inserted into the interior of the positive-pressure valve through the through holes,wherein a cap, which is connected to the plurality of leg portions of the negative valve via a locking unit and which holds the negative-pressure valve slidable with respect to the positive-pressure valve, is disposed in the interior of the positive-pressure valve,wherein a positive-pressure valve spring, which biases the positive-pressure valve towards the positive-pressure valve seat in the main-casing, is disposed between the positive-pressure valve and the sub-casing,wherein a negative-pressure valve spring, which biases the negative-pressure valve towards the negative-pressure valve seat in the positive-pressure valve, is disposed between the positive-pressure valve and the cap,wherein the positive-pressure valve is detached from the positive-pressure valve seat when a pressure within the fuel tank is equal to or larger than a certain value, and the negative-pressure valve is detached from the negative-pressure valve seat when the pressure within the fuel tank decreases to a certain value or lower than the atmospheric pressure,wherein a positive-pressure flow path for allowing fuel vapor to flow out from the fuel tank when the positive-pressure valve is detached from the positive-pressure valve seat is formed so as to pass by an outer side of the positive-pressure spring between the outer circumference of the positive-pressure valve and an inner circumference of the main-casing, andwherein a negative-pressure flow path for allowing outside air to flow into the fuel tank when the negative-pressure valve is detached from the negative-pressure valve seat is formed so as to pass by an outer side of the negative-pressure spring between an inner circumference of the positive-pressure valve, and the leg portions and an outer circumference of the cap and between the through holes and the leg portions. 2. The check valve of claim 1, wherein an opening portion communicating with the outside of the fuel tank is formed in an interior of the sub-casing,wherein a plurality of spring support ribs are provided so as to extend from a circumferential edge of the opening portion, outer circumferences of the spring support ribs constituting bearing seats for supporting one end of the positive-pressure spring, andwherein intervals between the spring support ribs communicate with the positive-pressure flow path to constitute flow paths which allow fuel vapor to flow out from the fuel tank. 3. The check valve of claim 2, wherein outer circumferences of the flow paths provided in the intervals between the spring support ribs each have a tapered surface which expands gradually diametrically as it extends towards the valve chamber. 4. The check valve of claim 1, wherein an outer circumferential shape of the positive-pressure valve and an outer circumferential shape of the negative-pressure valve which is disposed on the outer side of the distal end of the positive-pressure valve have a streamlined shape which extends from the main-casing towards the sub-casing. 5. The check valve of claim 1, wherein an outer circumference of the cap has a projecting surface which projects towards the sub-casing. 6. The check valve of claim 1, wherein a spring support portion is formed on an inner circumference of the positive-pressure valve, andwherein the positive-pressure spring is disposed in an inner circumference of the positive-pressure valve with the one end of the positive-pressure spring supported by the spring support portion. 7. The check valve of claim 1, wherein the cap has a bottomed cylindrical shape, and wherein one end of the negative-pressure valve is inserted into an interior thereof so as to be supported on a bottom surface of the cap. 8. The check valve of claim 1, wherein an inner circumferential surface of the main-casing which lies closer to a fuel tank side than the positive-pressure valve seat has a tapered surface which expands gradually diametrically as it extends towards an opening portion on a side facing the sub-casing. 9. The check valve of claim 1, wherein the positive-pressure valve seat of the main-casing comprises an annular rib which projects towards the sub-casing via a gap from an inner circumference of the main-casing.