Technical Field

[0001] The present invention relates to an inflation system for a life raft for emergency use on a marine vessel or aircraft.

Background of the Invention

[0002] Inflatable life rafts come in various sizes and capacities and are commonly provided on marine vessels and in aircraft for deployment in the event of an emergency at sea.

[0003] Inflatable life rafts are typically stored in a deflated state inside a two-piece plastic or fibreglass container or valise. The life raft is usually launched by manually throwing or lowering the entire container overboard and pulling an attached painter line, which triggers the inflation of the life raft. Alternatively, the marine vessel or aircraft may be provided with an auto-release mechanism for automatically releasing the life raft container.

[0004] When the painter line is pulled, this action activates one or more compressed gas cylinders which inflate the various air chambers that make up the life raft. The life raft inflates quickly, breaking a frangible connection between the two halves of the container and causing them to separate as the life raft bursts out of the container and inflates. With the life raft in an inflated state, ballast bags attached to the hull of the life raft are designed to fill with water, which helps stabilise the life raft.

[0005] This manual deployment process is time consuming and requires knowledge of how to operate and deploy the life rafts. Before the container is thrown overboard, the painter line typically needs to be unsecured and held onto as the container is thrown overboard. Then once the container is in the water, the painter line is pulled to initiate inflation of the life raft.

[0006] In certain emergency situations, such as in the event of a fire or if the vessel is listing heavily, it may be difficult or dangerous to access the painter line before throwing the container overboard. If the painter line is not held onto before throwing the container overboard, then in order to inflate the life raft, the painter line needs to be accessed from in the water. Object of the Invention

[0007] It is an object of the present invention to substantially overcome or at least ameliorate one or more of the above disadvantages, or to provide a useful alternative.

Summary of the Invention

[0008] In a first aspect, the present invention provides an inflation system for a life raft, the life raft having at least one inflatable cavity, the inflation system comprising:

a source of compressed gas;

a first valve in fluid communication between the inflatable cavity of the life raft and the compressed gas source, the first valve being able to be actuated between a closed state, in which the compressed gas source is isolated from the inflatable cavity, and an open state, in which the compressed gas source is in fluid communication with the inflatable cavity; a water sensitive actuator in communication with the first valve, the water sensitive actuator being adapted to be activated when the life raft is deployed on water and, when activated, to cause actuation of the first valve from the closed state to the open state.

[0009] In a preferred embodiment, the system further comprises an activation line extending between the water sensitive actuator and the first valve, the activation line allowing the water sensitive actuator to remotely cause actuation of the first valve from a closed state to an open state.

[0010] Preferably, the activation line is adapted to be charged with and hold compressed gas; the first valve is a pressure sensitive valve adapted to actuate from the closed state to the open state in response to a predetermined pressure drop in the activation line; and the water sensitive actuator is adapted to discharge the compressed gas from the activation line when activated.

[0011] Further preferably, the first valve is a pressure differential valve that is actuated from the closed state to the open state in response to a drop in pressure in the activation line.

[0012] Preferably, the water sensitive actuator includes a pin that is driven through a membrane to discharge the compressed gas in the activation line.

[0013] Further preferably, a fitting between the water sensitive actuator and the activation line provides said membrane.

[0014] In a preferred embodiment, the water sensitive actuator is a hydrostatic actuator. [0015] The system preferably further comprises an intake valve in fluid communication with the activation line for charging the activation line with compressed gas.

[0016] In a preferred embodiment, the system further comprises a container, in which the life raft is stored in a deflated state, wherein the water sensitive actuator is mounted externally of the container.

[0017] Preferably, the system further comprises a pressure gauge adapted to measure and indicate the pressure in the activation line.

[0018] In a preferred embodiment, the water sensitive actuator has a manual override mechanism allowing manual actuation of the water sensitive actuator.

[0019] In a second aspect, the present invention provides an inflatable life raft having the system defined in the first aspect above.

Brief Description of the Drawings

[0020] A preferred embodiment of the invention will now be described by way of specific example with reference to the accompanying drawings, in which:

[0021] Fig. 1 is a sectional view of an inflatable life raft system in a deflated, stowed state;

[0022] Fig. 2 depicts the inflatable life raft system of Fig. 1 in a deployed, inflated state;

[0023] Fig. 3 is a schematic diagram of the inflatable life raft system of Fig. 1;

[0024] Fig. 4 depicts a water sensitive actuator of the system of Figs. 1 to 3; and

[0025] Figs. 5 and 6 depict a pressure sensitive valve of the system of Figs. 1 to 3.

Detailed Description of the Preferred Embodiments

[0026] An inflation system is described, which is suitable for use in respect of inflatable life rafts for emergency use on boats, ships or aircraft. The inflation system provides a deflated life raft stored in a container that is simply deployed by throwing or lowering the container into the water. The life raft automatically inflates when the container enters the water, bursting out of the container and fully inflating ready for use.

[0027] As depicted in Fig. 1, the system 10 is fitted to a life raft 12 that is stored in a deflated state inside a container 14. The container 14 is typically cylindrical and comprises two semi-cylindrical halves formed from fibreglass, plastic or similar material. The container 14 is designed to be mounted on a marine vessel or aircraft for throwing, detaching or lowering into the water when the life raft 12 needs to be deployed in an emergency situation.

[0028] The system 10 includes at least one compressed gas source 16, depicted here as a gas canister, having a pressure sensitive valve 18, such as a pressure differential valve or other pressure activated valve. The gas canister 16 is adapted to inflate an inflatable cavity of the life raft 12 when the pressure sensitive valve 18 is opened. The compressed gas canister 16 is attached to the exterior of the inflatable life raft 12 and located within the container 14.

[0029] An activation line 20 extends from the pressure sensitive valve 18 to a water sensitive actuator 22, such as a hydrostatic actuator or other water activated device. The water sensitive actuator 22 is mounted on the outside of the container 14 and a pressure gauge 24 is fitted between the water sensitive actuator 22 and the activation line 20. The pressure gauge 24 detects and displays the pressure in the activation line 20 and is also mounted on the outside of the container 14, typically in a location suitable and accessible for maintenance checks.

[0030] A painter line 26 extends from the pressure sensitive valve 18, out of the container 14 and is attached at an accessible point on the outside of the container 14. The painter line 26 provides a manual override mechanism, allowing the pressure sensitive valve to be manually activated by pulling on the painter line 26 in the event that the life raft 12 does not inflate automatically.

[0031] Fig. 2 shows the life raft 12 from below in a fully deployed and inflated state, with the container 14 separated in two halves and the inflation system 10 still attached to the life raft 12.

[0032] The system 10 is depicted schematically in Fig. 3. The water sensitive actuator 22 is located on the outside of the container 14 and is connected to the activation line 20. A membrane provided in the fitting 30 seals the activation line 20 from the water sensitive actuator 22 and ambient environment. The activation line 20 is pressurised via a ball valve 28 and a pressure gauge 24 detects and displays the pressure in the activation line 20. The activation line 20 extends from the water sensitive actuator 22 to the pressure sensitive valve 18. The pressure sensitive valve 18 is arranged between the gas canister 16 and the inflatable cavity 15 of the life raft 12 and can be actuated between a closed state, in which the compressed gas canister 16 is isolated from the inflatable cavity 15 of the life raft 12, and an open state, in which the compressed gas canister 16 is in fluid communication with the inflatable cavity 15 of the life raft 12.

[0033] In operation, the container 14 is installed on a marine vessel or aircraft with the activation line 20 charged with compressed gas. In the event of an emergency, the container 14 is thrown into the water. When the water sensitive actuator 22 enters the water, it activates, rupturing the membrane in the fitting 30 and allowing the compressed gas in the activation line 20 to escape. This results in a loss of pressure in the activation line 20, which triggers actuation of the pressure sensitive valve 18 from the closed state to the open state, allowing compressed gas from the canister 16 to flow into the inflatable cavity 15, thereby inflating the life raft 12.

[0034] Fig. 4 depicts an example of a basic water sensitive actuator 22 connected to the activation line 20 via a T-piece 32 and the fitting 30. The fitting 30 is bolt with a blind hole extending axially from the bolt head and terminating at a thin membrane 34. The membrane 34 provides a seal between the activation line 20 and a vent 35 of the water sensitive actuator 22. The pressure gauge 24 is mounted to the T-piece 32.

[0035] The water sensitive actuator 22 has a casing 36 that is water permeable or that has openings allowing water to enter a chamber 38. The chamber 38 houses a spring-biased needle 40 that is held in a retracted position by a water-soluble element 42.

[0036] In operation, when the water sensitive actuator 22 enters the water, water enters the chamber 38 and dissolves the water soluble element 42, releasing the spring-biased needle 40. The spring-biased needle 40 is then driven through the membrane 34 of the fitting 30, which releases the compressed gas in the activation line 20 via the vent 35.

[0037] Alternative types of water sensitive actuators can also be used, such as hydrostatic actuators. For example, when the hydrostatic actuator is immersed in water, a hydrostatic valve opens and allows the ingress of water, which contacts a water sensitive element that then releases a coil spring. The spring drives a needle, which perforates the membrane in the fitting.

[0038] The fitting 30 can be manufactured in different sizes and with different thread sizes and diameters to fit different water sensitive actuators. For example, the fitting may be manufactured with a standard 1/2 inch NPT external thread. The fitting may also be manufactured with a specific blind hole diameter and thread, such as with a 11/32 inch diameter having a 1/8 inch NPT internal thread. Typically, the fitting is manufactured from brass, aluminium, bronze or another soft metal or alloy and the membrane 34 is approximately 0.3mm thick. Rather than being manufactured with an integrally formed membrane 34, the fitting 30 may be formed using an encapsulated burst disc instead.

[0039] Alternatively, the water sensitive actuator or the activation line may be constructed with a built-in burst disc, obviating the need for the fitting 30. In this embodiment, the water sensitive actuator and the activation line are connected directly and the needle of the water sensitive actuator ruptures the burst disc, releasing pressure in the activation line.

[0040] Figs. 5 and 6 depict an example of the pressure sensitive valve 18 of the inflation system 10. Fig. 5 depicts the pressure sensitive valve 18 in a closed state and Fig. 6 depicts the pressure sensitive valve 18 in an open state. The pressure sensitive valve 18 has an inlet port 46 which is connected in fluid communication with the canister of compressed gas and an outlet port 48 in fluid communication with the inflatable cavity. A valve member 50 is adapted to move between the closed state position, shown in Fig. 5, and the open state position, shown in Fig. 6. A third port 52 is connected to the activation line 20, such that pressure in the activation line biases the valve member 50 to the closed state position.

[0041] In operation, while the activation line 20 maintains a certain pressure, the valve member 50 is held in the closed state position, maintaining the pressurised gas within the canister. However, when the activation line 20 loses pressure, the pressurised gas forces the valve member 50 to the open state position and allows the pressurised gas to flow from the canister, passing from the inlet port 46 to the outlet port 48 and into the inflatable cavity, which inflates the life raft.

[0042] The activation line also includes a ball valve for pressurising the activation line and a pressure gauge for measuring pressure in the activation line. The activation line extends to the exterior of the container and the hydrostatic actuator and pressure gauge are typically mounted on the exterior of the container.

[0043] Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.