Patent Description:
Specifically, the present disclosure relates to a potable, waste or grey water tank having a pressure compensation mechanism equalising a pressure inside of the water tank with a surrounding environment, as well as an aircraft section and an aircraft having such water tank.

Currently, potable water in an aircraft is transported in special tanks or containers. In order to provide the potable water to a consumer, such as a galley, lavatory or the like, the interior of the tank is pressurised. For instance, bleed air from an aircraft engine or other compressed air is usually fed into the tank, so that the built-up pressure facilitates conveying the water towards the consumers through a distribution network for water (see e.g. document <CIT>).

This does not only require energy consuming bleed air from the aircraft engines.

Moreover, the tank itself has to be designed and formed to withstand the pressure in the tank. This is usually achieved by providing a tank having a spherical form or a cylindrical form with spherical ends. This special form of the tank requires additional space in the aircraft, since the tank cannot be placed anywhere in the aircraft. For instance, special brackets surrounding such tank are required for transportation and installation of the tank. In addition, the shell of the tank is dimensioned relatively thick, in order to withstand the pressurisation.

Thus, water storage in an aircraft requires a lot of space for storage, has a high weight, and has a negative influence on the energy consumption.

It is thus an object of the present disclosure to provide an improved water tank, as well as an aircraft section and aircraft having such a tank.

This object is solved by the present invention as defined in the independent claim <NUM>.

According to a first aspect to better understand the present disclosure, a water tank configured for operation in an aircraft comprises a rigid tank shell and a pressure compensation mechanism configured to equalise a pressure inside of the rigid tank shell with an environment. A rigid tank shell is to be understood as a shell forming a tank that delimits a fixed internal volume for storing water. The size of the shell does not change (significantly) when the tank shell is empty or filled with water or another liquid. In other words, a rigid tank shell distinguishes over a flexible tank shell, such as a bladder.

An environment of the tank or the rigid tank shell is to be understood as a direct environment surrounding the rigid tank shell, such as a storage or cargo area of a vehicle, in which the tank is installed. The environment of the tank can further mean a more general surrounding, such as an environment of the vehicle, in which the tank is installed.

The water tank can be used for storage of potable water. Alternatively, the water tank can be used to store waste, such as toilet waste, or grey water, such as waste water from sinks in a lavatory or galley, that can be reused for other purposes.

Furthermore, since the water tank has a pressure compensation mechanism, the water, other liquid or waste is stored without being pressurised. This allows building the tank of a lighter and thinner material, since the tank shell does not have to withstand the interior pressure as with pressurised water tanks or a high exterior pressure acting on the tank. It is to be understood that the rigid tank shell can withstand a (positive and negative) pressure that may occur during normal operation of the tank. The maximum to-be-expected pressure built-up is during filling the tank from a pressurised source or in case of an unexpected pressure drop in an environment of the tank or inside of the tank (e.g., in case a drain port or the like has a defect). However, such pressure occurrence is of only short duration and with a reduced peak (compared to conventional tanks) due to the pressure compensation mechanism.

Any brackets as in conventional tanks may have a simplified structure, so that they are lighter, or can even be omitted entirely. This further allows building the tank in any desired form, irrespective of any pressure-optimized spherical or cylindrical shape. As a mere example, the shape of the rigid tank shell may at least in portions follow, surround or encase other components in the surrounding environment of the tank. Thus, the tank can be arranged in any desired place of the aircraft, such as between stringers, frames, ducts, tanks or other primary structure and secondary structure elements. This saves a significant amount of space in the aircraft, while storage space for water can even be increased.

In the water tank, the pressure compensation mechanism comprises a shutoff member configured to move between a closed position, a first open position allowing air to enter the rigid tank shell and a second open position allowing air to leave the rigid tank shell. Thus, a pressure inside of the rigid tank shell can be equalised, irrespective of a pressure (development) inside and outside of the shell.

As mere examples, in an aircraft, the pressure outside of the shell, such as in a storage or cargo area of the aircraft, may decrease when the aircraft reaches a higher altitude. The shutoff member moving into the second open position allows a pressure equalisation of the interior of the shell with respect to the surrounding environment, so that no increased pressure builds up in the tank. Likewise, if the water level in the tank raises or sinks, such as during filling of the tank and removing water from the tank, respectively, an increasing/decreasing pressure inside of the shell can be avoided by the shutoff member moving into the second position or first position, respectively. In any case, a pressure equalisation is easily achieved, which ensures that the rigid tank shell does not need to be built to withstand high pressures, be it a positive or negative pressure relative to the surrounding environment. Thus, the water tank can be built much lighter than conventional tanks. A high pressure means a pressure applied to a water tank in conventional tanks, where the interior of the tank is continuously pressurised to convey the water from the tank to a water consumer. It is to be understood, that the water tank of this disclosure is still designed to withstand critical cases with large pressure differences, such as during filling with an external pressure source or a sudden drop of pressure in the environment of the tank.

Since the water tank is not pressurised, there is no need for bleed air from the aircraft's engine(s). Thus, the disclosed water tank is particularly valuable for bleedless aircrafts, i.e. aircrafts or aircraft engines designed to not provide bleed air. As a mere example, propeller engines or other (future) impellent may not have the capability of providing bleed air. Thus, the disclosed water tank can be employed with any type of engine.

Moreover, the shutoff member also avoids spilling of water out of the tank shell, when in the closed position. In other words, the shutoff member shuts off (closes) any passage from the interior of the rigid tank shell to the surrounding environment.

In a variant, the shutoff member can move into opposite directions from the closed position when achieving the first open position and the second open position. Specifically, when starting in the closed position, the shutoff member moves in a first direction towards the first open position. Moreover, when starting in the closed position, the shutoff member moves in a second direction towards the second open position, wherein the first and second direction are opposite to one another. As a mere example, the shutoff member can be configured to move towards an interior of the rigid tank shell, where it reaches the first open position, and to move towards an exterior of the rigid tank shell where it reaches the second open position.

Alternatively or additionally, the shutoff member can be configured to achieve a first degree of aperture in the first open position and to achieve a second degree of aperture in the second open position. A degree of aperture means the size of an opening evolving when the shutoff member moves from the closed position towards the first or second open position. In other words, the degree of aperture corresponds to the size of a cross-section of the opening or air passage way of the opened shutoff member. For instance, the first degree of aperture can be smaller than the second degree of aperture, so that in the second open position more air can stream through the opening in the rigid tank shell.

In another variant, the shutoff member can be a flap hinged on one side and configured to pivot in a first direction from the closed position towards the first open position and to pivot in a second direction from the closed position towards the second open position. For instance, the flap can be hinged to a portion of the rigid tank shell.

Alternatively, the shutoff member can be a flap hinged on one side and configured to pivot from the closed position towards the first and second open position in the same direction, for example, towards an interior or an exterior of the tank. For instance, the flap can be hinged to a portion of the rigid tank shell. As a mere example, the flap may achieve different degrees of aperture in the first and second open position.

In addition or alternatively, the flap can be configured to close an opening in the rigid tank shell, when the shutoff member is in the closed position. The opening in the rigid tank shell may be a dedicated opening for pressure equalisation, i.e. for air moving inside or out of the rigid tank shell.

In any case, the flap can be configured to move to the first open position and the second open position depending on the required degree of aperture, i.e. depending on a rapidness of the pressure compensation, wherein the second open position having the larger degree of aperture allows faster pressure compensation than the first open position. It is further to be understood that the flap can be configured to move in any direction (towards the interior or exterior of the rigid shell tank) depending on the direction of pressure compensation. In other words, if an increased pressure in the interior of the rigid tank shell has to be compensated, the flap can move towards the exterior of the rigid tank shell, and if a negative pressure in the interior of the rigid tank shell develops, the flap can move towards the interior of the rigid tank shell. This can be applied for the first and second open position, only for the first open position or only for the second open position.

Alternatively or additionally, the shutoff member can be a diaphragm mechanism or membrane mechanism that is configured to open and close an opening in the rigid tank shell. When in the closed position, the diaphragm closes the opening in the rigid tank shell in an airtight manner. The first and second open positions can be positions of the diaphragm where it forms a smaller and a larger aperture, respectively. The opening in the rigid tank shell may be a dedicated opening for pressure equalisation, i.e. for air moving inside or out of the rigid tank shell.

It is likewise possible to provide a flap with a diaphragm mechanism, for example, the diaphragm mechanism forming part of the flap and closing an opening in the flap. In this case, the diaphragm mechanism can open to achieve the first or second position, while the flap can open to achieve the other of the first or second position. As a mere example, opening the diaphragm allows air to enter the rigid tank shell, i.e. the shutoff member achieves the first open position. Opening the flap, for example, towards an exterior of the rigid tank shell allows air to leave the rigid tank shell, i.e. the shutoff member achieves the second open position. It is to be understood that the flap can also move towards the interior of the rigid tank shell, in order to achieve the second open position.

Also alternatively or additionally, the shutoff member can comprise an axially movable plug, configured to move between the closed position and the first and second open position. The plug can constitute a valve having a valve seat and a valve disc configured to close an opening at the valve seat. The valve disc (i.e., the movable block) can move from the closed position (contacting the valve seat) to the first open position achieving a first degree of aperture, and to also move to the second open position achieving a second degree of aperture. The movement to the first and second open position can be in the same direction or can be an opposite directions. In the letter case, the valve disc and valve seat may be configured in such a manner that the valve disc can move through the valve seat.

In a further variant, the pressure compensation mechanism can comprise an air filter arranged to cover an opening evolving when the shutoff member moves from the closed position to the first open position. As a mere example, the air filter may be arranged in the opening in the rigid tank shell, through which air streams into and out of the rigid tank shell. Thus, any dust, particles or other elements are prevented from entering the interior of the rigid tank shell. This ensures hygienic requirements for the potable water storage.

As another example, the air filter is connected to the shutoff member, such as the flap, and a portion of the rigid tank shell, so that the air filter spans between the shutoff member and the rigid tank shell, when the shutoff member moves into the first open position. The air filter may be mounted to the rigid tank shell in such a manner, that the shutoff member does not contact the air filter, when the flap moves into the second open position. This can be easily achieved if a movement of the shutoff member towards the second open position is in an opposite direction than when moving into the first open position. Likewise, if a movement of the shutoff member towards the second open position is in the same direction as when moving into the first open position, the shutoff member may move further from the first position, while the filter does not move (further). Thus, the air entering the interior of the rigid tank shell is filtered through the air filter, while air released from the interior of the rigid tank shell can move quickly in an opening next to the air filter, i.e., without being filtered, since there is no hygienic reason for filtering air leaving the tank.

As a further example, the shutoff member may be implemented as a double flap. The shutoff member can be formed as a flap configured to move to the second open position and comprises a further flap or other shutoff member configured to move to the first open position. For instance, the further flap can be smaller than the entire shutoff member (larger flap), wherein the further flap closes an opening in the shutoff member (larger flap), the opening comprising the air filter. Thus, when the further flap opens towards the first open position, air entering the rigid tank shell is filtered. When the entire shutoff member (the larger flap comprising the air filter covered by the further flap) moves into the second open position, the air filter is moved out of the way and an opening covered by the shutoff member appears allowing the air leaving the rigid tank shell.

In case the shutoff member is a diaphragm mechanism, the air filter may be arranged in such a manner, that an aperture of the diaphragm in the first open position is covered by the air filter, while an aperture of the diaphragm in the second open position is not covered by the air filter or is only partially covered by the air filter. For instance, the air filter may have a first size corresponding to the opening achieved by the diaphragm the first open position, while the diaphragm may achieve a larger opening in the second open position, so that a ring-shaped opening around the air filter allows air to leave the rigid tank shell unfiltered and, hence, in a fast manner.

In another variant, an opening or aperture of the shutoff member in the first open position and the second open position may have a different areal size, such as a different opening or aperture cross-section. As a mere example, the opening cross-section in the first open position is smaller than the open cross-section in the second open position. This increases safety measures of the pressure compensation mechanism. Specifically, in case of filling the tank, the air inside of the rigid tank shell has to quickly move out of the tank compared to air entering the rigid tank shell when water is removed and delivered to a consumer. Likewise, in an aircraft a drop of air pressure inside of the aircraft may occur, such as in case of a lack of cabin pressure. In such case, the pressure of the air inside of the tank rapidly increases compared to the drop of pressure in the surrounding of the tank, so that a fast removal of air out of the interior of the rigid tank shell is required. A larger opening cross-section helps removing the air from the inside of the tank in a fast manner, so that a fast pressure equalisation can be achieved.

Likewise, a fast pressure equalisation may be necessary, if a pressure in the interior of the rigid tank shell drops. For instance, in order to fill the tank or remove (waste) water from the tank, there is usually a duct and valve arranged between the rigid tank shell and an exterior (skin) of the aircraft. In case of a failure, the interior of the rigid tank shell may unintentionally be fluidly connected to the exterior of the aircraft, where a low-pressure may be present, such as during flying at a high altitude. The pressure compensation mechanism is then able, to equalise the pressure in the interior of the tank.

In a further variant, the tank can further comprise a controller configured to receive a status signal from the pressure compensation mechanism. For example, the status signal may comprise information and/or data about a pressure in the interior of the rigid tank shell (relative to a pressure outside of the rigid tank shell), a pressure outside of the rigid tank shell, a position of the shutoff member, an opening degree or opening cross-sectional area of the shutoff member, or the like.

As a mere example, the pressure compensation mechanism can be configured to generate and transmit the status signal indicating the information about the shutoff member, such as a position of the shutoff member.

The pressure compensation mechanism and the controller can be connected to one another via a data bus, a network or other data exchange infrastructure.

In yet a further variant, the controller can be further configured to send a control signal to the pressure compensation mechanism. The pressure compensation mechanism can then be configured to receive the control signal and to move the shutoff member into a position corresponding to the control signal. Thus, the controller can control pressure equalisation by controlling the shutoff member, particularly by controlling an open or closed position thereof.

This may facilitate pressure equalisation, since the controller may be connected to a more general aircraft controller, so that flight status and/or flight operation data and/or cabin-related data may be used by the controller to control the pressure compensation mechanism. For example, the general aircraft controller may provide a signal indicating an increasing flight altitude and/or a decreasing cabin pressure, so that the controller may control the pressure compensation mechanism accordingly.

In another variant, the pressure compensation mechanism can further comprise a rupture disc configured to rupture, if a pressure difference between the inside and the surrounding environment of the rigid tank shell exceeds a threshold value. Such rupture disc allows a rapid pressure equalisation. Rapid pressure equalisation may be necessary, in case of a lack of cabin pressure or other reasons leading to a relatively large (positive or negative) pressure difference between the interior and exterior of the rigid tank shell. The threshold value, i.e. the relative pressure at which the rupture disc ruptures, can be chosen in such a manner that the rigid tank shell is not harmed due to the relative pressure difference between the interior and exterior of the shell.

The rupture disc may comprise an electrical contact or a sensor, which induce a signal recognisable at the controller, such as the lack of an electrical connection or a signal generated at the rupture disc. Thus, the controller is informed of the rupture of the disc and, hence, the unusual pressure difference and pressure compensation. The controller may then inform a personal working in the aircraft accordingly.

In yet another variant, the tank can further comprise at least one water level sensor configured to measure a water level in the rigid tank shell and to transmit a water level signal. For instance, the water level signal can be sent to the controller. The at least one water level sensor may comprise a continuous water level sensor measuring a water level over the entire height of the rigid tank shell, i.e., from zero to maximum, and/or a maximum water level sensor configured to output a signal only if the maximum water level in the rigid tank shell is reached (such as an overflow warning signal).

In a further variant, the tank can comprise a pump configured to pump water from the inside of the rigid tank shell to a water supply line. The water supply line may be connected to a water supply network or system connecting the water tank with one or more consumers of potable water. The water supply line, hence, is connected with the interior of the rigid tank shell, preferably at a bottom or sump of the rigid tank shell.

In yet a further variant, the tank can comprise an overflow port connected to an overflow line and configured to release water from the rigid tank shell, if a water level in the inside of the rigid tank shell exceeds a threshold. The threshold may be a maximum water line or fill level in the interior of the rigid tank shell. The overflow port may be used (activated) when the water filling process is not stopped in time. For instance, a hydraulically effective cross-section of the overflow port and overflow line should be larger than the hydraulically effective cross-section of the filling line/duct. This facilitates removing the air from the interior of the rigid tank shell, i.e. equalising the pressure in the interior of the rigid tank shell constantly and particularly in case of overfilling the tank.

Optionally, the overflow port can fluidly connect the overflow line with a housing of the pressure compensation mechanism. Thus, the pressure compensation mechanism having an opening in the rigid tank shell may also be used to drain excess water in the tank. Moreover, the overflow port and overflow line (i.e., an overflow duct or the like) may also be employed to remove water from the interior of the rigid tank shell, in order to avoid a flooding of the aircraft fuselage.

In another variant, the overflow port can be configured to release air from the inside of the rigid tank shell, if the air inside the rigid tank shell exceeds a threshold pressure. In other words, the overflow port and/or overflow line can be used to remove excess air from the inside of the rigid tank shell, for example, when the shutoff member is in the first or second position. Thus, the overflow port and/or overflow line can be employed to guide water and/or air from the interior of the rigid tank shell to an exhaust port.

In yet another variant, the tank can further comprise at least one actuator configured to move the shutoff member between the closed position and the first open position and/or between the closed position and the second open position. The at least one actuator may be a spring-loaded actuator, a motor, a hydraulic or pneumatic actuator, a mechanically operated actuator (e.g. cable controlled actuator) or the like configured to be coupled to and move the shutoff member. As a mere example, a first actuator may be employed to move the shutoff member from its closed position to the first open position, while a second actuator different from the first actuator can be employed to move the shutoff member from its closed position to the second open position. It is to be understood that a single actuator may be used to move the shutoff member to any position.

According to a second aspect to better understand the present disclosure, an aircraft section comprises at least one tank according to the first aspect or one of its variants.

Furthermore, the aircraft section can also comprise a water consumer fluidly connected with the at least one tank and configured to receive water from the at least one tank. For instance, water can be pumped from the at least one tank to the water consumer and through a water pipe network.

In a variant, the aircraft section can further comprise a water connection configured to be connected to a water supply, and a fill valve configured to open and close a fluid connection between the water connection and the rigid tank shell. The water connection can be any connection in an interior space of the aircraft section and/or a connection that is accessible from an exterior of the aircraft section. Thus, by connecting a water supply, such as a hose or pipe of an exterior water supply station, to the water connection and with the fill valve opened, the rigid tank shell can be filled with water.

It is to be understood that the controller of the potable water tank can be employed to control the fill valve. As a mere example, the controller may receive a signal from the at least one water level sensor, and the controller then operates, on the basis of this signal, the fill valve, such as opening the fill valve to initiate the filling process and to close the fill valve and the filling process. Thus, an automatic filling of the potable water tank can be performed.

According to a third aspect to better understand the present disclosure, an aircraft comprises at least one tank according to the first aspect or one of its variants.

Alternatively or additionally, the aircraft can comprise at least one aircraft section according to the second aspect or one of its variants.

The present disclosure is not restricted to the aspects and variants in the described form and order. Specifically, the description of aspects and variants is not to be understood as a specific limiting grouping of features. It is to be understood that the present disclosure also covers combinations of the aspects and variants not explicitly described. Thus, each variant or optional feature can be combined with any other aspect, variant, optional feature or even combinations thereof.

In the following, the present disclosure will further be described with reference to exemplary implementations illustrated in the figures, in which:.

It will be apparent to one skilled in the art that the present disclosure may be practiced in other implementations that depart from these specific details.

<FIG> schematically illustrates a potable water tank <NUM> comprising a rigid tank shell <NUM> configured to store a particular amount of potable water (illustrated as a hashed area in the interior of the rigid tank shell <NUM>). The tank further comprises a pressure compensation mechanism <NUM>, which is exemplary illustrated as a valve. It is to be understood that the pressure compensation mechanism <NUM> can be implemented in any form fulfilling at least the here described capabilities.

The pressure compensation mechanism <NUM> is configured to equalise the pressure inside of the rigid tank shell <NUM> with the environment surrounding the rigid tank shell <NUM>. The environment surrounding the rigid tank shell <NUM> can be a cargo or storage compartment of a vehicle <NUM> (<FIG>) or may refer to the environment surrounding the vehicle <NUM> as will be explained further below. The pressure compensation mechanism <NUM> may be configured to open and close a fluid connection between the interior and the exterior of the rigid tank shell <NUM>.

For example, the pressure compensation mechanism <NUM> comprises a shutoff member <NUM>, <NUM> (exemplary illustrated in <FIG> and <FIG>) configured to move between a closed position, a first open position and a second open position. In the first open position, the shutoff member <NUM>, <NUM> allows air to enter the rigid tank shell, i.e. from the surrounding environment into the tank. In the second open position, the shutoff member <NUM>, <NUM> allows air to leave the rigid tank shell <NUM>, i.e. out of the interior of the rigid tank shell <NUM>.

<FIG> illustrates further features, which are each optional to the tank <NUM>. Although each of <FIG> illustrates one or more of these features, the present disclosure is not restricted to the illustrated combination of features. It is to be understood that the tank <NUM> can be equipped with one or more of the illustrated features irrespective of the particular drawing.

For example, the tank can comprise a controller <NUM> configured to receive a status signal from the pressure compensation mechanism <NUM>. The controller <NUM> is connected with one or more or elements of the tank <NUM>, that can generate and output a signal processable by the controller <NUM> or that can be controlled by the controller <NUM>. Such signal lines to and from the controller <NUM> are illustrated in dashed lines in <FIG>, while not all possible signal lines are drawn for legibility of the drawings. As a mere example, a signal line <NUM> between the controller <NUM> and the pressure compensation mechanism <NUM> is not illustrated in <FIG>, but shown in <FIG>.

Another optional feature of the tank <NUM> can be a water level sensor <NUM> configured to measure a water level in the rigid tank shell <NUM>. The water level sensor <NUM> may be configured to continuously measure a water level inside of the tank from empty to full. Such water level sensor <NUM> may reach over the entire height of the rigid tank shell <NUM>, in order to detect a current water level. Alternatively, an ultrasonic, radar or similar sensor may be employed at the top of the rigid tank shell <NUM> that is capable of determining the fill level of the tank <NUM>.

In addition or alternatively, a water level sensor <NUM> may be employed that is configured to measure a maximum water level in the rigid tank shell <NUM>. In other words, maximum water level sensor <NUM> only generates a corresponding signal once the maximum water level inside of the rigid tank shell <NUM> is reached. The maximum water level sensor <NUM> may also be contemplated as a backup to water level sensor <NUM> for security reasons.

In order to fill the water tank <NUM>, a water connection <NUM> and a fill valve <NUM> are optionally provided. The water connection <NUM> connects an interior of the rigid tank shell <NUM> with a water supply (not illustrated), while the fill valve <NUM> can be configured to open and close a fluid connection between the water connection <NUM> and the rigid tank shell <NUM>. In <FIG> a fluid connection is provided between the fill valve <NUM> and a bottom or sump of the rigid tank shell <NUM> as one possible example.

In order to remove water from the tank <NUM>, particularly to provide the water to a water consumer (not illustrated), a water supply line <NUM> and a pump <NUM> can be provided. The water supply line <NUM> may be connected to the fluid connection between the fill valve <NUM> and the rigid tank shell <NUM>. Alternatively or additionally, the water supply line <NUM> may be connected to the fill valve <NUM>, which in this case can be a shut-off valve or a three-way valve. In another optional example, the pump <NUM> is arranged inside of the rigid tank shell <NUM>. Alternatively or additionally, the pump <NUM> can be combined with the fill valve <NUM>. This may allow to use the pump <NUM> also to fill water from the water connection <NUM> into the rigid tank shell <NUM>.

A further optional feature of the tank <NUM> can be an overflow port <NUM> configured to release water from the rigid tank shell <NUM>, particularly if a water level in the interior of the rigid tank shell <NUM> exceeds a threshold level. The overflow port <NUM> can be connected to an overflow line <NUM>, in order to remove the overflow water and to avoid flooding in the surrounding of the tank <NUM>.

For instance, the overflow line <NUM> may connect the overflow port <NUM> (and hence the interior of the rigid tank shell <NUM>) with an ambient, such as an environment or ambient of a vehicle <NUM> (<FIG>) where the tank <NUM> is installed. Optionally, an overflow valve <NUM> may be installed in overflow line <NUM>, in order to close overflow line <NUM>, if required. As a mere example, the overflow valve <NUM> may be arranged at a border between an interior and exterior of a vehicle where the tank <NUM> is installed, so that the overflow line <NUM> can be blocked from the ambient. Since an atmosphere in the ambient may have a different pressure than the interior of the rigid tank shell <NUM> and/or the interior of the vehicle <NUM>, the overflow valve <NUM> shall be closed to avoid a pressure equalisation between the ambient atmosphere and the interior of the rigid tank shell <NUM>, if it is not desired. The overflow valve <NUM> should be opened, for example, in case of filling water into the tank or when draining the tank, in order to allow ventilation (pressure equalisation). In addition, the overflow valve <NUM> can be opened in the event of overfilling the rigid tank shell <NUM>, in order to allow draining of the excess water.

Furthermore, the fill valve <NUM> may be mechanically connected to the overflow valve <NUM> (which mechanical connection is illustrated as a dashed line between both valves). For instance, if the fill valve <NUM> is opened, the overflow valve <NUM> is also opened. This allows filling the rigid tank shell <NUM>, while equalising the pressure inside of the rigid tank shell <NUM> with an environment (ambient) of the vehicle <NUM>, in which the tank <NUM> is installed.

As a mere example, filling the tank <NUM> with water may begin with connecting a water supply to water connection <NUM> and opening the fill valve <NUM> (e.g., controlled by controller <NUM>). The overflow port <NUM> regulates the air pressure inside of the rigid tank shell <NUM> by leaving the air out of the rigid tank shell <NUM>. The at least one water level sensor <NUM>, <NUM> sensor signal to the controller <NUM>, which closes fill valve <NUM>, if the intended fill level is reached. In case the overflow port <NUM> is blocked or otherwise closed, the pressure compensation mechanism <NUM> regulates the pressure inside of the rigid tank shell <NUM>. The pressure compensation mechanism <NUM> may also send a signal to the controller <NUM> indicating a valve position or the like.

Draining the tank <NUM> can also be controlled by controller <NUM>, e.g., by controlling valve <NUM> to open and releasing water through water connection <NUM>. At the same time, overflow port <NUM> may be used to regulate the air pressure inside of the rigid tank shell <NUM>, e.g. by allowing air to move into the rigid tank shell <NUM> through overflow line <NUM> and overflow port <NUM>. In case the overflow port <NUM> is blocked or otherwise closed, the pressure compensation mechanism <NUM> regulates the pressure inside of the rigid tank shell <NUM>. The pressure compensation mechanism <NUM> may also send a signal to the controller <NUM> indicating a valve position or the like.

Supplying water from tank <NUM> to a water consumer can also be controlled by controller <NUM>, e.g., by controlling pump <NUM> pumping water into water supply line <NUM>. The pressure compensation mechanism <NUM> regulates the pressure inside of the rigid tank shell <NUM>. The pressure compensation mechanism <NUM> may also send a signal to the controller <NUM> indicating a valve position or the like.

In case of a rapid decompression (either inside of the tank <NUM> or in the surrounding of the tank <NUM>), the pressure compensation mechanism <NUM> regulates pressure compensation by allowing air to enter or leave the rigid tank shell <NUM>.

<FIG> illustrates details of a variant of the tank <NUM>. The same features as in <FIG> are indicated by the same reference numerals and their description will be omitted, in order to avoid redundant explanations. Any of the features described with respect to <FIG> may also be employed in a tank as illustrated in <FIG> and vice versa.

For example, the tank <NUM> can further comprise a floating valve <NUM> configured to allow air to enter and exit the interior of the rigid tank shell <NUM>. In case the water level in the tank <NUM> rises to a predetermined level, such as a water level close under or at the floating valve <NUM>, a floating element of the floating valve <NUM> will be pushed by the water against an opening in the floating valve <NUM>, thereby blocking the air passageway through this opening.

In other words, the floating valve <NUM> is a mechanical and non-controllable pressure compensation mechanism. Thus, the floating valve <NUM> can be integrated into the pressure compensation mechanism <NUM>. For example, the floating valve <NUM> can form the shutoff member of the pressure compensation mechanism <NUM> or can be arranged besides the shutoff member <NUM>, <NUM> in order to complement the functionality of the shutoff member <NUM>, <NUM>.

Moreover, the floating valve <NUM> is a further safety measure, for example during filling of the tank <NUM>. For example, in case the overflow port <NUM> is blocked or otherwise closed, air can leave the rigid tank shell <NUM> during the filling process.

Further optionally, the tank <NUM> can comprise a check valve <NUM> configured to allow air to move out of or into the rigid tank shell <NUM>, if a pressure difference between the interior and exterior of the rigid tank shell <NUM> exceeds a predetermined threshold. For example, the check valve <NUM> may comprise a spring element (not illustrated), which closes the check valve <NUM>. If the pressure difference acting on a valve element induces a force on the spring element exceeding the closing force of the spring element, the check valve <NUM> automatically opens in a pure mechanical manner. Thus, a rapidly occurring pressure difference may be compensated faster and in an easier manner than with the pressure compensation mechanism <NUM> alone.

As a mere example, during draining of the tank <NUM>, the check valve <NUM> may be a safety measure to allow air to enter the rigid tank shell <NUM>. For instance, if the overflow port <NUM> is blocked or otherwise closed or in case the water drains faster than expected, the check valve <NUM> opens to allow air to enter the rigid tank shell <NUM>.

Alternatively, the check valve <NUM> may be employed to regulate the pressure inside of the rigid tank shell <NUM> during water supply, i.e. when pump <NUM> is activated. In this case, the pressure compensation mechanism <NUM> may be employed as a safety measure or as an additional pressure compensation measure.

<FIG> further illustrates signal lines <NUM> and <NUM> connecting the water level sensors <NUM>, <NUM> with the controller <NUM>, respectively. Such signal lines may be employed to facilitate communication between the controller and the water level sensors <NUM>, <NUM>.

<FIG> illustrates details of another variant of the tank <NUM>. The same features as in <FIG> are indicated by the same reference numerals and their description will be omitted, in order to avoid redundant explanations. Any of the features described with respect to <FIG> may also be employed in a tank as illustrated in <FIG> and vice versa.

<FIG> illustrates a signal line <NUM> between controller <NUM> and pressure compensation mechanism <NUM>. Such a signal line may be employed to facilitate communication between the controller and the pressure compensation mechanism <NUM>, in both directions, since the pressure compensation mechanism <NUM> may generate data signals and may also receive data signals to be controlled.

The pressure compensation mechanism <NUM> is illustrated as comprising a housing <NUM>. This housing <NUM> may provide a water tight housing of the entire pressure compensation mechanism <NUM>, so that any water from an interior of the rigid tank shell <NUM> may enter an interior of the housing <NUM>, but may be blocked from spreading in the surrounding environment of the tank <NUM>. The housing <NUM> may be equipped with an air release mechanism <NUM>, in order to allow air to leave and/or enter the rigid tank shell <NUM>, when the pressure compensation mechanism <NUM> is in the first or second open position.

The pressure compensation mechanism <NUM> can comprise a rupture disc <NUM> configured to rupture if a pressure difference between the interior and surrounding environment of the rigid tank shell <NUM> exceeds a threshold value. For example, the rupture disc <NUM> may simply break, i.e., rupture, under the threshold pressure. This pressure may act on the rupture disc <NUM> in either direction, i.e. into or out of the tank <NUM>. Thus, a rapid pressure equalisation can be achieved, for example, in case of sudden pressure increase or decrease inside or outside of the rigid tank shell <NUM>.

In the illustrated example of <FIG>, the overflow port <NUM> is arranged at or in the housing <NUM> of the pressure compensation mechanism <NUM>. Thus, the overflow port <NUM> can fluidly connect the overflow line <NUM> with an interior of the housing <NUM>. As a mere example, if the rupture disc <NUM> breaks or in case the pressure compensation mechanism <NUM> releases air (or in rare and unintended cases water) from the interior of the rigid tank shell <NUM>, this air (and/or water) can be released via overflow line <NUM>. Of course, the housing <NUM> can be equipped with an air release mechanism <NUM>, in order to allow air to leave and/or enter the rigid tank shell <NUM>, when the pressure compensation mechanism <NUM> is in the first or second open position.

<FIG> schematically illustrates an exemplary shutoff member <NUM>, <NUM> of the pressure compensation mechanism <NUM> in different positions. The shutoff member is illustrated as a flap <NUM>, exemplary mounted to the rigid tank shell <NUM> via a hinge 122a arranged on one side of the flap <NUM>. The flap <NUM> is configured to pivot in a first direction and a second direction. It is to be understood that any other form of shutoff member <NUM>, <NUM> can be implemented, as long as the described functionality is achieved.

In the upper image in <FIG> the shutoff member <NUM> is in a closed position. For instance, the shutoff member <NUM> closes an opening in the rigid tank shell <NUM> in an airtight and watertight manner. This is particularly relevant to prevent water from unintentionally spreading out of the tank <NUM> through this opening, for example due to movement of the water in certain flight situations. The air release mechanism <NUM> is also schematically illustrated in the upper image in <FIG>, but has been omitted in the other images of <FIG>, for clarity reasons.

The middle image of the shutoff member <NUM> in <FIG> shows the shutoff member <NUM> in a first open position allowing air to enter the rigid tank shell <NUM>. The first open position can exemplarily be achieved by moving the shutoff member <NUM> in a first direction, here towards an interior of the rigid tank shell <NUM>.

The middle image of <FIG> additionally shows another optional feature, such as an actuator <NUM>. This actuator <NUM>, exemplarily illustrated as a spiral spring, can be configured to close the shutoff member <NUM>, i.e., to move the shutoff member <NUM> into the closed position as illustrated in the upper image of <FIG>. In case a pressure difference between the interior and exterior of the rigid tank shell <NUM> occurs, the shutoff member <NUM> can be pushed out of the way (i.e., out of the opening in the rigid tank shell <NUM>) against the biasing force of the spring actuator <NUM>. Once the pressure is equalised, spring actuator <NUM> brings the shutoff member <NUM> back into the closed position.

A further optional feature illustrated in <FIG> is an air filter <NUM> arranged to cover an opening evolving when the shutoff member <NUM> moves from the closed position to the first open position. For instance, the air filter <NUM> can be connected to the shutoff member <NUM> and/or the rigid tank shell <NUM>, so that the air filter <NUM> covers the opening in the rigid tank shell <NUM>. This allows air to enter the interior of the rigid tank shell <NUM>, while any particles, dust or the like is prevented from reaching the water stored in tank <NUM>.

In the bottom left image of <FIG> the shutoff member <NUM> is illustrated in a second open position allowing air to leave the rigid tank shell <NUM>. Here, the flap-like shutoff member <NUM> is moved in an opposite direction from the closed position compared to the moving direction towards the first open position. The degree of opening of the shutoff member <NUM> may be larger in the second open position, so that the opening cross-section is also larger in the second open position than in the first open position. This may be particularly relevant, if a sudden pressure drop in the surrounding environment of the tank <NUM> occurs, or in case of a fast filling of the tank <NUM>. The second open position of the shutoff member <NUM> allows a rapid pressure equalisation, thereby avoiding high stresses on the rigid tank shell <NUM> due to an internal pressure.

Another optional feature is illustrated in bottom image of <FIG> in form of an actuator <NUM>. The illustrated actuator <NUM> may be a motor, hydraulic or pneumatic actuator, a mechanical actuator (e.g., cable controlled actuator) or the like configured to control movement of the shutoff member <NUM>. Although <FIG> illustrates the actuator <NUM> to move the shutoff member <NUM> into the second open position, it is to be understood that the actuator <NUM> can also move the shutoff member <NUM> towards the first open position (middle image of <FIG>).

The actuator <NUM> can be controlled by controller <NUM>, so that a pressure equalisation/compensation can be actively controlled on the basis of any data available to controller <NUM>.

It is to be understood that the pressure compensation mechanism <NUM> can comprise both actuators <NUM>, <NUM>, in order to facilitate uncontrolled and controlled movement of the shutoff member <NUM>. Alternatively, the pressure compensation mechanism <NUM> may comprise only one or none of the actuators <NUM>, <NUM>.

In the bottom right image of <FIG>, a further option is illustrated, where the shutoff member <NUM> moves to the second open position in the same direction as when moving to the first open position. This direction exemplary can be to the interior of the rigid tank shell <NUM>. As illustrated (starting from the configuration of the middle image of <FIG>) the shutoff member <NUM> can move away from the air filter <NUM>, so that not only a degree of aperture increases from the first open position to the second open position, but also an unhindered air passageway is achieved for a fast pressure compensation. In other words, the shutoff member <NUM> moves into a position, where the air filter <NUM> can be bypassed by air streaming during the pressure compensation. This particular second open position may be employed in case of a pressure drop in the environment of the tank <NUM>, i.e., when air has to leave the rigid tank shell <NUM>. Moreover, this particular second open position may also be employed in case of a pressure drop in the interior of the rigid tank shell <NUM>, for example, if the fill valve <NUM> accidentally opens, although the aircraft <NUM> flies at a high altitude and the pressure in the ambient environment of the aircraft <NUM> is less than in the interior of the rigid tank shell <NUM>.

<FIG> schematically illustrates a further exemplary shutoff member <NUM> in the form of a diaphragm mechanism <NUM>. The upper images of <FIG>, from left to right, show the diaphragm mechanism <NUM> in a closed position, a first open position and a second open position. Specifically, in the closed position, the shutoff member <NUM> is completely closed, so that an airtight and/or watertight closure is formed.

It is to be noted that <FIG> illustrates the inner edge of the diaphragm mechanism <NUM> as a small circle, in order to schematically illustrate this edge, although there is no opening at this small circle due to the airtight and/or watertight closure. In addition, the shutoff member <NUM> is placed in the rigid tank shell <NUM>, which is not illustrated explicitly, but which is arranged around the outer circumference of the shutoff member <NUM>.

In the first open position, the diaphragm mechanism <NUM> can be configured to open to a certain degree, i.e. to achieve a first degree of aperture. The upper middle image of <FIG> additionally illustrates the optional air filter <NUM>. When moving the diaphragm mechanism <NUM> to the first open position, a degree of aperture may be achieved that corresponds to (or is slightly smaller than) the size of the air filter <NUM>. For example, air entering the rigid tank shell <NUM> is filtered, so that no particles or dust or the like enters the tank <NUM>.

In the second open position (upper right image of <FIG>) the diaphragm mechanism <NUM> can move to a larger degree of aperture. This may expose the entire filter <NUM>, which can, for example, be mounted to the shutoff member <NUM> and/or the rigid tank shell <NUM> via mounts <NUM>. Thereby, an opening 123a of the shutoff member <NUM> is entirely opened. This allows air to leave or enter the rigid tank shell <NUM> in an easy manner. Specifically, since the air can bypass the air filter <NUM>, and since the degree of aperture is larger than in the first open position, a larger flow of air can be achieved in the second open position.

<FIG> further illustrates, in the bottom image of <FIG>, an exemplary shutoff member <NUM>, <NUM> comprising a flap <NUM> and a diaphragm mechanism <NUM>. For example, the flap <NUM> can comprise a hinge 122a (as in <FIG>) pivoting the flap <NUM> between the closed position and, for example, the second open position. The flap <NUM> comprises the diaphragm mechanism <NUM>, i.e. the diaphragm mechanism <NUM> is arranged in or on the flap <NUM> and moves together with the flap <NUM> around hinge 122a. The diaphragm mechanism <NUM> is illustrated in the first open position, corresponding to the upper middle image of <FIG>.

As illustrated in the bottom image of <FIG>, the flap <NUM> can also comprise the optional air filter <NUM>, which is arranged in an opening in the flap <NUM>. The diaphragm mechanism <NUM> can close the opening in the flap <NUM> when moving to the closed position (like in the upper left image of <FIG>). Furthermore, if the air filter <NUM> is not present, the diaphragm mechanism <NUM> in the first open position exposes an opening in the flap <NUM>.

<FIG> schematically illustrates an exemplary aircraft section <NUM>, particularly a bottom section of a cross-section of an aircraft <NUM>. The aircraft section <NUM> can comprise at least one tank <NUM>, such as the tank <NUM> illustrated in one of <FIG>. As shown in <FIG>, the shape of the tank <NUM>, particularly the shape of the rigid tank shell <NUM> can be adapted to the shape and form of the aircraft section <NUM>. Thus, the tank <NUM> can be positioned in the aircraft section <NUM> in a space-saving manner and/or a volume of the rigid tank shell <NUM> can be optimised.

The aircraft section <NUM> may further comprise a water consumer, illustrated in <FIG> as a water supply line <NUM> and a sink <NUM>. Moreover, the aircraft section <NUM> can comprise a water connection <NUM> configured to be connected to a water supply (not illustrated). For instance, the water connection <NUM> may be arranged at an outer skin of the aircraft <NUM>, so that a water supply can be connected from an exterior of the aircraft <NUM> to the water connection <NUM>. A fill valve <NUM> (<FIG>) can be arranged and configured to open and close a fluid connection between the water connection <NUM> and the rigid tank shell <NUM>.

<FIG> schematically illustrates another exemplary aircraft section <NUM>, particularly a bottom section of a cross-section of an aircraft <NUM>. The aircraft section <NUM> can comprise at least one tank <NUM>, such as the tank <NUM> illustrated in one of <FIG>. As shown in <FIG>, the aircraft section <NUM> can further comprise a further tank <NUM>, such as a waste water tank <NUM>. This further water tank <NUM> may be designed to withstand a continuous positive or negative pressure, such as a conventional pressurised tank <NUM> having a cylindrical and/or spherical shape.

The shape of the tank <NUM>, particularly the shape of the rigid tank shell <NUM> can be adapted to the shape of the further water tank <NUM>. For instance, the tank <NUM> of the present disclosure can be designed to at least partially surround the further water tank <NUM>. In addition, the tank <NUM> can be adapted to the shape and form of the aircraft section <NUM>. Thus, the tank <NUM> can be positioned in the aircraft section <NUM> and in the vicinity of other secondary structures of the aircraft <NUM> in a space-saving manner and/or a volume of the rigid tank shell <NUM> can be optimised to the installation space the tank <NUM>.

<FIG> schematically illustrates a further optional feature, where the pressure compensation mechanism <NUM> is arranged at an outer skin of the aircraft <NUM>. Specifically, the pressure compensation mechanism <NUM> penetrates the outer skin of the aircraft <NUM>, so that pressure compensation can be achieved between the interior of the rigid tank shell <NUM> and the ambient environment of the aircraft <NUM>.

It is to be understood that such configuration may alternatively or additionally be provided for the overflow port <NUM>. This would save weight and installation costs for an overflow line <NUM>.

Claim 1:
Water tank (<NUM>) configured for operation in an aircraft (<NUM>), the tank comprising:
a rigid tank shell (<NUM>); and
a pressure compensation mechanism (<NUM>) configured to equalise a pressure inside of the rigid tank shell (<NUM>) with an environment,
characterised in that
the pressure compensation mechanism (<NUM>) comprises a shutoff member (<NUM>, <NUM>) configured to move between a closed position, a first open position allowing air to enter the rigid tank shell (<NUM>) and a second open position allowing air to leave the rigid tank shell (<NUM>).