FIELD OF THE INVENTION

The present invention relates to climb and dive valves. Such valves may also be known as pressure/vacuum relief valves and breather valves.

BACKGROUND

A vessel (e.g. a storage tank) can be subject to a variety pressure conditions. For example, a fuel tank on an aircraft will be subject to changing atmospheric pressure when the aircraft is climbing and when the aircraft is diving. During a climbing operation (e.g. take-off), atmospheric pressure decreases but tank pressure remains constant and therefore the fuel tank is at risk of rupturing if the pressure differential becomes too high. During a diving operation (e.g. landing), atmospheric pressure increases but tank pressure remains constant and therefore the fuel tank is at risk of imploding if the pressure differential becomes too high. In a similar way, a vessel on the ground may be at risk of rupturing when pumping fluid into the vessel, and may be at risk of imploding when pumping fluid out of the vessel.

To reduce the risk of rupture and implosion caused by changing pressure differentials across the walls of an aircraft fuel tank, climb valves (pressure relief valves) and dive valves (vacuum relief valves) are typically installed on a wall of the tank. A climb valve will open to allow air out of the tank if the pressure inside the tank exceeds a threshold pressure when the aircraft is climbing, whereas a dive valve will open to allow air into the tank if pressure inside the tank becomes falls below a threshold pressure when the aircraft is diving.

A climb valve and a dive valve may be installed on a tank as two (or more) separate valves. Alternatively, combined climb and dive valves are also commercially available. However, combined valves are typically a vacuum relief valve joined to the side of the inlet of a pressure relief valve and therefore only minimal space reduction is achieved.

It is an object of the present invention to provide a single valve that can act as both a climb valve (pressure relief valve) and a dive valve (vacuum relief valve) and is more compact than the prior art valves described above.

SUMMARY OF INVENTION

According to a first aspect of the invention, there is provided a valve comprising: a valve body; an outer fluid channel passing axially through the valve body; an outer closure element arranged within the valve body and movable between an open position and a closed position to open and close the outer fluid channel respectively; and an outer bias element configured to bias the outer closure element toward the closed position; wherein the outer closure element comprises: an inner fluid channel passing axially through the outer closure element and in fluid communication with the outer fluid channel; an inner closure element movable relative to the outer closure element between an open position and a closed position to open and close the inner fluid channel respectively; and an inner bias element configured to bias the inner closure element toward the closed position; and wherein: the outer bias element and the inner bias element are configured to bias the outer closure element and the inner closure element respectively in opposite directions.

Accordingly, when a pressure differential across the valve in a first direction exceeds a threshold value, the biasing force of the outer bias element may be overcome and the outer closure element may move to the open position. However, because the inner closure element is biased in the opposite direction to the outer closure element, the inner closure element may remain in the closed position. Similarly, when a pressure differential across the valve in a second direction opposite to the first direction exceeds a threshold value, the biasing force of the inner bias element may be overcome and the inner closure element may move to the open position. However, because the inner closure element is biased in the opposite direction to the outer closure element, the outer closure element may remain in the closed position.

In this way, the outer closure element comprises an inner relief valve to relieve pressure in one direction while in itself acting a relief valve for relieving pressure in the opposite direction. This allows for a compact valve that can perform pressure relief during both climbing operations and diving operations.

In some embodiments, the valve body comprises an outer seat (e.g. at an inner surface of the valve body) and the outer bias element is configured to bias the outer closure element to engage the outer seat in the closed position, and the outer bias element comprises an inner seat (e.g. at an inner surface of the outer closure element) and the inner bias element is configured to bias the inner closure element to engage the inner seat in the closed position.

The outer bias element may comprise a spring, optionally a compression spring or a torsion spring.

The inner bias element may comprise a spring, optionally a compression spring or a torsion spring.

The diameter of the inner fluid channel may be smaller than the diameter of the outer fluid channel.

The inner closure element may be smaller in diameter than the outer closure element.

In some embodiments, the outer closure element and the inner closure element may be axially movable between their respective open and closed positions. For example, the outer closure element and the inner closure element may both comprise a poppet (i.e. an axially extending stem having an enlarged radially extending head at one end of the stem). In such embodiments, the outer bias element and the inner bias element may both comprise a compression spring.

The inner closure element may be (fully or partially) located within the outer closure element. For example, the inner closure element may be physically located inside the outer closure element.

In some embodiments, the outer closure element and the inner closure element are configured to swing between their respective open and closed positions. For example, the outer closure element and the inner closure element may both comprise a flap. In such embodiments, the outer bias element and the inner bias element may both comprise a hinge having a torsion spring.

The inner closure element may be attached to the outer closure element.

In a second aspect of the present invention, there is provided a vessel comprising the valve according to the first aspect.

The outer fluid channel of the valve may be in fluid communication with the interior of the vessel and the exterior of the vessel (i.e. the environment outside the vessel, e.g. the

atmosphere).

The vessel may be a fuel tank, e.g. a fuel tank for an aircraft. In a third aspect of the present invention, there is provided a valve comprising: a valve body; an outer fluid channel passing through the valve body; an outer poppet arranged within the valve body and axially movable between an open position and a closed position to open and close the outer fluid channel respectively; and an outer spring configured to bias the outer poppet toward the closed position; wherein the outer poppet comprises: an inner fluid channel passing through the outer poppet and in fluid communication with the outer fluid channel; an inner poppet axially movable relative to the outer poppet between an open position and a closed position to open and close the inner fluid channel respectively; and an inner spring configured to bias the inner poppet toward the closed position; and wherein: the outer spring and the inner spring are configured to bias the outer poppet and the inner poppet respectively in opposite directions.

In a fourth aspect of the present invention, there is provided a valve comprising: a valve body; an outer fluid channel passing through the valve body; an outer flap arranged within the valve body and movable between an open position and a closed position to open and close the outer fluid channel respectively; and an outer hinge comprising a spring configured to bias the outer flap toward the closed position; wherein the outer flap comprises: an inner fluid channel passing through the outer flap and in fluid communication with the outer fluid channel; an inner flap movable relative to the outer flap between an open position and a closed position to open and close the inner fluid channel respectively; and an inner hinge comprising a spring configured to bias the inner closure element toward the closed position; and wherein: the outer hinge and the inner hinge are configured to bias the outer flap and the inner flap respectively in opposite directions.

While the invention has been described above, it extends to any inventive combination set out above, or in the following description or drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described, by way of example only, with reference to the

accompanying drawings, in which:

Figure 1 shows a sectional side view of a valve in accordance with a first embodiment of the invention.

Figure 2 shows a sectional side view of the valve of Figure 1 in use during a climb operation.

Figure 3 shows a sectional side view of the valve of Figure 1 in use during a dive operation.

Figure 4 shows a sectional side view of a valve in accordance with a second embodiment of the invention.

Figure 5a shows a sectional side view of the valve of Figure 4 in use during a climb operation. Figure 5b shows a perspective view of the valve of Figure 4 in use during a climb operation. Figure 6a shows a sectional side view of the valve of Figure 4 in use during a dive operation. Figure 6b shows a perspective view of the valve of Figure 4 in use during a dive operation. DETAILED DESCRIPTION OF THE DRAWINGS

Figure 1 shows a valve 100 in accordance with the first embodiment of the invention.

Valve 100 comprises two valve body halves 110 and 120. The two valve body halves 110 and 120 are tubular and are joined together to form an axial fluid channel 111 defined by the hollow portions of valve body halves 110 and 120 that fluid may flow through.

Valve 100 further comprises an outer poppet 130 provided within the outer channel 111. Outer poppet 130 comprises an axially extending annular stem 132, at the end of which is an annular head 134. Head 134 has a greater diameter than stem 132 and includes an annular radially extending washer 135 having a slightly wider diameter than head 134. Washer 135 may be made from an elastomeric material.

The inner wall of valve body half 110 includes a tapered portion that tapers radially inward so that valve body half 110 has a section of reduced inner diameter. The tapered portion acts as an inner seat 118 for engaging with head 134 and/or washer 135 of outer poppet 130.

Outer poppet 130 further comprises an outer spring 136 that surrounds stem 132 but has a diameter less than head 134. Outer spring 136 biases outer poppet 130 toward inner seat 118 by pushing against head 134. The diameter of head 134 and/or washer 135 is at least the inner diameter of the valve body half 110 at outer seat 118 so that when outer poppet 130 is engaged with inner seat 118, a seal is formed to block fluid from flowing through outer channel 111.

Outer poppet 130 is tubular and its hollow portion defines an axial inner fluid channel 131 that is in fluid communication with outer fluid channel 111. Outer poppet 130 further comprises an inner poppet 140 provided within the inner fluid channel 131.

Inner poppet 140 comprises an axially extending stem 142, at the end of which is a head 144 having a larger diameter than stem 142. Head 144 includes an annular radially extending washer 145 having a diameter slightly larger than head 144. Washer 145 may be made of an elastomeric material.

The inner wall of outer poppet 130 includes a first tapered portion that tapers radially inward so that outer poppet 130 has a section of reduced inner diameter. The first tapered portion acts as an inner seat 138 for engaging with head 144 and/or washer 145.

Inner poppet 140 further comprises an inner spring 146 that surrounds stem 142 but has a diameter less than head 144. Inner spring 146 biases inner poppet 140 toward inner seat 138 by pushing against head 144. The diameter of head 144 and/or washer 145 is at least the inner diameter of outer poppet 130 at inner seat 118 so that when inner poppet 140 is engaged with inner seat 138, a seal is formed to block fluid from flowing through inner channel 131.

Outer poppet 130 and inner poppet 140 are biased in opposite directions and therefore open in opposite directions. In Figure 1, outer poppet 130 is biased toward the left side of Figure 1 and inner poppet 140 is biased toward the right side.

Inner poppet 140 also comprises a secondary head 154 which is provided at the end of stem 142 opposite head 144. Secondary head 154 also comprises an annular radially extending washer 155 having a diameter slightly larger than the diameter of secondary head 155. With regard to assembly of inner poppet 140, stem 142 and secondary head 154 may be provided as one component and head 154 may be provided as another component to be attached to the opposite end of stem 142.

The interior of outer poppet 130 further comprises a second tapered portion at the opposite end of outer poppet 130 to seat 138. The second tapered portion tapers radially inward so that outer poppet 130 has a second section of reduced diameter and acts as a secondary seat 139 for engaging with secondary head 154. Secondary head 154 engages with secondary seat 139 in the same direction as head 144 engages with seat 138 and blocks the opposite end of inner channel 131 when inner poppet 140 is in the closed position. The combination of head 144 and secondary head 154 provides a better sealing arrangement within inner channel 131 compared to head 144 alone and improves fluid flow characteristics through the valve during use.

In use, valve 100 may be attached to a vessel (e.g. a fuel tank) by attaching valve body half 110 to a wall (e.g. the top wall) of the vessel so that the outer fluid channel 111 connects the inside of the vessel to the atmosphere.

In Figure 1, the left side of valve 100 is in fluid communication with the interior of the vessel and the right side is in fluid communication with the atmosphere.

Figure 1 shows valve 100 at rest or in an equilibrium pressure state. In this state, outer poppet 130 is in the closed position due to the bias of outer spring 136 and inner poppet 140 is in the closed position due to the bias of inner spring 146. Thus, fluid is unable to flow through valve 100 because both outer fluid channel 111 and inner fluid channel 131 are blocked by outer poppet 130 and inner poppet 140 respectively.

Figure 2 shows valve 100 when the internal pressure of the vessel is higher than the external pressure and the pressure differential has exceeded a threshold such that the biasing force of outer spring 136 is overcome. In this state, the internal fluid pushes outer popper 130 away from outer seat 118 against the bias of outer spring 136. Furthermore, because inner poppet 140 is biased in the opposite direction to outer poppet 130 (i.e. inner poppet 140 is biased in the same direction as the fluid flow), inner poppet 140 remains engaged with inner seat 138. Thus, in this state, outer poppet 130 is in the open position and inner poppet 140 is in the closed position.

Internal fluid is then able to flow through valve 100 and vent to the atmosphere via outer channel 111 to relive the pressure inside the vessel. This continues until the pressure differential falls below the threshold and the biasing force of outer spring 136 returns outer poppet 130 to the closed position. Figure 3 shows valve 100 when the external pressure of the vessel is higher than the internal pressure and the pressure differential has exceeded a threshold such that the biasing force of inner spring 146 is overcome. In this state, the external air pushes inner poppet 140 away from inner seat 138 against the bias of inner spring 146. Furthermore, because outer poppet 130 is biased in the opposite direction to inner poppet 140 (i.e. outer poppet 130 is biased in the same direction as the fluid flow), outer poppet 130 remains engaged with inner seat 138. Thus, in this state, outer poppet 130 is in the closed position and inner poppet 140 is in the open position.

External air is then able to flow through valve 100 into the vessel via inner channel 131 (and a portion of outer channel 111 either side of inner channel 131 to increase the pressure inside the vessel. This continues until the pressure differential falls below the threshold and the biasing force of inner spring 146 returns inner poppet 140 to the closed position.

Thus, valve 100 of the first embodiment provides a compact poppet-in-poppet valve design for maintaining an equilibrium pressure differential between the interior and exterior of a vessel.

Figure 4 shows a valve 200 in accordance with a second embodiment of the invention.

Valve 200 comprises two valve body halves 210 and 220 and an outer seat 218 in the form of an annular disc. The two valve body halves 210 and 220 are tubular and are joined together with outer seat 218 sandwiched in between the two valve body halves to form an axial fluid channel 211 (defined by the hollow portions of valve body halves 210 and 220 and the axial hole in the centre of outer seat 218) that fluid may flow through.

Valve 200 further comprises an outer flap 230 attached to outer seat 218 by an outer hinge 236. Outer hinge 236 is spring-loaded. It comprises a torsion spring and is configured to bias outer flap 230 toward outer seat 218 to a closed position. The diameter of outer flap 230 is greater than that of the axial hole in outer seat 218 and therefore outer flap 230 fully covers the hole in outer seat 218 when in the closed position. However, outer flap 230 is also substantially an annular disc shape having an axial hole. The axial hole of outer flap 230 is smaller in diameter than the axial hole of outer seat 218 and defines an inner fluid channel 231 that fluid may flow through.

Attached to outer flap 230 is an inner flap 240, which is attached by an inner hinge 246. Inner hinge 246 is spring-loaded. It comprises a torsion spring and is configured to bias inner flap 240 toward an inner seat 238 on a surface of outer flap 230 to a closed position. The diameter of inner flap 240 is smaller than the diameter of outer flap 230 but larger than the diameter of inner fluid channel 231 (i.e. the axial hole in outer flap 230). Thus, in the closed position, inner flap 240 closes inner fluid channel 231 and blocks fluid from passing through it. Outer flap 230 and inner flap 240 are biased in opposition directions and therefore open in opposite directions. In Figure 4, outer flap 230 is biased toward the right side and inner flap 240 is biased toward the left side.

In use, valve 200 may be attached to a vessel (e.g. a fuel tank) by attaching valve body half 210 to a wall (e.g. the top wall) of the vessel so that the outer fluid channel 211 connects the inside of the vessel to the atmosphere.

In Figure 4, the left side of valve 200 is in fluid communication with the interior of the vessel and the right side is in fluid communication with the atmosphere.

Figure 4 shows valve 100 at rest or in an equilibrium pressure state. In this state, outer flap 230 is in the closed position due to the bias of outer hinge 236 and inner flap 240 is in the closed position due to the bias of inner hinge 246. Thus, fluid is unable to flow through valve 200 because both outer fluid channel 211 and inner fluid channel 231 are blocked by outer flap 230 and inner flap 240 respectively.

Figures 5a and 5b show valve 200 when the internal pressure of the vessel is higher than the external pressure and the pressure differential has exceeded a threshold such that the biasing force of inner hinge 236 is overcome. In this state, the internal fluid pushes inner flap 240 away from inner seat 238 against the bias of inner hinge 236. Furthermore, because outer flap 230 is biased in the opposite direction to inner flap 240 (i.e. outer flap 230 is biased in the same direction as the fluid flow), outer flap 230 remains engaged with outer seat 218. Thus, in this state, inner flap 240 is in the open position and outer flap 230 is in the closed position.

Internal fluid is then able to flow through valve 200 and vent to the atmosphere via inner channel 231 (and portions of outer channel 211 either side of inner channel 231) to relive the pressure inside the vessel. This continues until the pressure differential falls below the threshold and the biasing force of inner spring 246 returns inner flap 240 to the closed position.

Figures 6a and 6b show valve 200 when the external pressure of the vessel is higher than the internal pressure and the pressure differential has exceeded a threshold such that the biasing force of outer hinge 236 is overcome. In this state, the external air pushes outer flap 230 away from outer seat 218 against the bias of outer hinge 236. Furthermore, because inner flap 240 is biased in the opposite direction to outer flap 230, inner flap 240 remains engaged with inner seat 238. Thus, in this state, outer flap 230 is in the open position and inner flap 240 is in the closed position. External air is then able to flow through valve 200 into the vessel via outer channel 211 to increase the pressure inside the vessel. This continues until the pressure differential falls below the threshold and the biasing force of outer hinge 236 returns outer flap 230 to the closed position.

Thus, valve 200 of the second embodiment provides a compact flap-in-flap valve design for maintaining an equilibrium pressure differential between the interior and exterior of a vessel.

As exemplified by the two embodiments described above, the present invention provides a compact single valve design by providing inner and outer closure elements that are biased in opposite directions. Various modifications will be apparent to those skilled in the art. For example, in addition to poppets and flaps, other types of closure elements may be used in similar outer and inner arrangements.