Closure device for a fluid vessel
A closure device ( 2 ) for a fluid vessel ( 1 ) comprises a bistable valve arrangement which includes first and second valve rim portions ( 4, 5 ) and a valve member ( 3 ) engageable with either of the rim portions ( 4, 5 ) respectively to define an open position in which fluid ( 9 ) can exit the vessel ( 1 ) and a closed position in which fluid ( 9 ) is substantially prevented from exiting the vessel ( 1 ). The valve is arranged to close automatically when an impulse is exerted against the valve member ( 3 ). This can occur for example when the vessel ( 1 ) is knocked over and the fluid ( 9 ) therein exerts pressure against the valve member ( 3 ).
1. A closure device for a fluid vessel, the closure device comprising a bistable valve through which a liquid exits the vessel, the bistable valve comprising a valve member and first and second valve seats, the valve member having an open position in which the liquid is permitted to exit the vessel and a closed position in which the liquid is substantially prevented from exiting the vessel, wherein a first magnetic force attracts the valve member to the second valve seat thereby holding the valve member in the open position, wherein the valve member closes in response to the liquid inside the vessel pressing against the valve member sufficiently to overcome the first magnetic force, and wherein the valve member is retained in the closed position by a second magnetic force.
2. The closure device according to claim 1 , wherein the valve member engages the first valve seat in the closed position.
3. The closure device according to claim 1 , wherein the valve member engages the second valve seat in the open position.
4. The closure device according to claim 1 , wherein the first valve seat is above the second valve seat when the vessel is upright, and wherein the first valve seat delimits the closed position of the valve member, and the second valve seat delimits the open position of the valve member.
5. The closure device according to claim 1 , wherein the valve member is a unitary moving part.
6. The closure device according to claim 1 , wherein the first valve seat is located on a removable lid of the fluid vessel and the second valve seat is located on a main part of the fluid vessel.
7. The closure device according to claim 1 , wherein the first valve seat comprises a first valve rim portion and the second valve seat comprises a second valve rim portion, and wherein the valve member selectively engages the first and second valve rim portions.
8. The closure device according to claim 7 , wherein each valve rim portion is formed, at least in part, around an inner circumference of the vessel.
9. The closure device according to claim 7 , wherein the closure device comprises a gasket which the valve member sealingly engages in the closed position.
10. The closure device according to claim 7 , wherein in the open position, an opening is defined between the valve member and the second valve rim portion which extends substantially around the circumference of the vessel.
11. The closure device according to claim 1 , wherein the valve member comprises a magnetic material.
12. The closure device according to claim 1 , wherein a greater force is required to move the valve member from the closed position than is required to move the valve member from the open position.
13. A closure device for a fluid vessel, the closure device comprising a bistable valve through which a liquid exits the vessel, the bistable valve comprising a valve member and first and second valve seats, the valve member having an open position in which the liquid can exit the vessel and a closed position in which the liquid is substantially prevented from exiting the vessel, wherein the valve member comprises a disc, wherein a magnetic force attracts the valve member to the second valve seat thereby holding the valve member in the open position, and wherein the bistable valve closes in response to the liquid inside the vessel pressing against the valve member sufficiently to overcome the magnetic force.
14. The closure device according to claim 13 , wherein the disc comprises a plastics material impregnated with magnetic material.
15. The closure device according to claim 8 , wherein the valve member comprises a dome-like raised protrusion on an upper surface of the valve member.
16. The closure device according to claim 1 , wherein the device comprises a pressure relief valve.
17. A fluid vessel comprising a closure device, the closure device comprising a bistable valve through which a liquid exits the vessel, the bistable valve comprising a valve member, the valve member having an open position in which the liquid is permitted to exit the vessel and a closed position in which the liquid is substantially prevented from exiting the vessel, wherein an attractive magnetic force holds the valve member in the open position, wherein the valve member closes in response to the liquid inside the vessel pressing against the valve member sufficiently to overcome the attractive magnetic force, and wherein the valve member is retained in the closed position by a second magnetic force.