Patent Description:
Aircraft can be equipped with steam ovens for cooking or heating food for passengers of the aircraft. The steam ovens are typically provided as part of a galley insert which enables easy installation and removal of the oven from an aircraft galley. The food is heated in a food preparation chamber of the oven using steam. The steam can be provided by supplying water to the oven and heating the water within the oven to evaporate it, or by injecting steam into the oven directly. Valves are used to control the water or steam supply to the chamber. Control of these valves is important, since a failure thereof can cause the oven to flood with hot water or steam, leading to possible injuries to flight attendants or passengers. <CIT>, <CIT> and ITTA20120005A1 disclose arrangements of the prior art. <CIT> discloses an oven system powered by an on-board grid of an aircraft, for which a plug connection is formed at the rear of the oven.

The present disclosure aims to provide an improved steam oven.

According to one aspect of the invention there is provided a steam oven for an aircraft galley according to claim <NUM>.

The valve may be electrically connected to a first power supply to receive power therefrom and the sensor may be electrically connected to a second power supply to receive power therefrom, wherein the second power supply is electrically isolated from the first power supply.

In an optional example, the actuation of the valve by the control unit is not based on the valve state detection by the sensor.

In an optional example, the valve comprises a circuit board including the sensor, wherein the circuit board is arranged to receive and process sensor data from the sensor and output a signal indicative of the actual valve state based on the sensor data. In another optional example, the sensor is configured to transmit sensor data to a remote electronics unit for processing.

The valve may optionally be a normally-closed solenoid valve. The solenoid valve may comprise a solenoid and a plunger, wherein the solenoid, when powered, may move the plunger from an extended position in which the plunger extends into the pipeline to block the passage of fluid therethrough, to a retracted position in which the plunger is retracted from the pipeline to permit the passage of fluid therethrough. The sensor may be arranged to detect whether the plunger is in the extended position or the retracted position. The solenoid valve may optionally comprise a biasing member arranged to bias the plunger to the extended position when the solenoid is not powered. In an example, the biasing member is a spring.

In an optional example, the steam oven comprises a verification circuit configured to verify that the expected valve state corresponds to the actual state of the valve detected by the sensor. The expected valve state may be the expected state of the valve after receiving an actuation command from the control unit.

An aspect of the invention provides an aircraft galley insert comprising a steam oven as disclosed herein.

An aspect of the invention provides a method of operating a steam oven in an aircraft galley according to claim <NUM>.

Optionally, the actuation of the valve by the control unit is not based on the valve state detection by the sensor.

In an optional example, the valve comprises a circuit board including the sensor. The method may comprise using the circuit board to receive and process sensor data from the sensor and generate a signal indicative of the actual valve state based on the sensor data.

In another optional example, the method comprises transmitting sensor data from the sensor to a remote electronics unit for sensor data processing.

The valve may optionally be a normally-closed solenoid valve. The method may comprise powering a solenoid of the solenoid valve and thereby causing a plunger of the solenoid valve to move from an extended position in which the plunger extends into the pipeline to block the passage of fluid therethrough, to a retracted position in which the plunger is retracted from the pipeline to permit the passage of fluid therethrough. The sensor may detect whether the plunger is in the extended position or the retracted position. The method may comprise biasing the plunger to the extended position using a spring when the solenoid is not powered.

The method may optionally comprise verifying that an expected valve state corresponds to the actual valve state detected by the sensor. The expected valve state may be the expected state of the valve after receiving an actuation command from the control unit.

An aspect of the present disclosure provides a method of operating a steam oven as disclosed herein.

Certain embodiments of the invention will now be described, by way of example only, and with reference to the accompanying drawings.

<FIG> shows a schematic diagram of an example of an embodiment of the present disclosure. The Figure shows a steam oven <NUM> attached via a connector <NUM> to a water supply <NUM> external to the steam oven <NUM>. The steam oven <NUM> may be part of a galley insert for an aircraft. The steam oven <NUM> comprises a food preparation chamber <NUM> for receiving food for heating or cooking, a pipeline <NUM> arranged to receive water from the water supply <NUM>, and a heating element <NUM>. The heating element <NUM> may be located inside or outside of the food preparation chamber <NUM>. A first end of the pipeline <NUM> is connected to the connector <NUM>. A second end of the pipeline <NUM> comprises a nozzle <NUM> for spraying water received from the water supply <NUM> onto the heating element <NUM> to create steam <NUM> for heating food in the food preparation chamber <NUM>.

In some embodiments (not shown), the steam oven <NUM> may instead receive steam from an external supply, rather than water. Thus the steam oven <NUM> may not comprise the heating element <NUM> and the nozzle <NUM>, and the pipeline <NUM> may be arranged to supply steam directly from the external supply to the food preparation chamber <NUM>.

The pipeline <NUM> comprises a valve <NUM> configured to regulate the flow of water (or steam) through the pipeline <NUM>. The valve <NUM> has an open state in which the valve <NUM> permits the flow of fluid through the pipeline <NUM>, and a closed state in which the valve <NUM> prevents the flow of fluid through the pipeline <NUM>. The pipeline <NUM> may further comprise additional valves <NUM> configured in this way. In this example, the valve <NUM> is a solenoid valve <NUM>. However, other valve types may be used.

The solenoid valve <NUM> is electrically connected to a control unit <NUM>. The control unit <NUM> is configured to actuate the valve <NUM> between the open and closed states. The control unit <NUM> can transmit a command signal to the valve <NUM> corresponding to a desired state of the valve <NUM>. For example, an "open" command signal may be transmitted when it is desired for the valve <NUM> to be in an open state, and a "close" command signal may be transmitted when it is desired for the valve <NUM> to be in a closed state. If the valve <NUM> is operating correctly, then the valve <NUM> will be actuated according to the command signal. An expected valve state is the state in which the valve <NUM> is expected to be after receiving an actuation command from the control unit <NUM>, assuming the valve and control unit are operating correctly.

The valve <NUM> comprises a sensor <NUM> configured to detect an actual state of the valve <NUM>. The actual valve state is the state which the valve <NUM> is actually in after receiving an actuation command from the control unit <NUM>. The sensor <NUM> will be described in more detail later with reference to <FIG> and <FIG>.

The actual valve state may differ from the expected valve state if there is a fault in the system. For instance, a fault in the control unit <NUM> may cause an "open" command signal to be transmitted to the valve <NUM>, when it was desired to close the valve <NUM>. In another example, a fault in the valve <NUM> may cause the valve <NUM> to remain in an open or partially open state, even after receiving a "close" command signal from the control unit <NUM>. In some embodiments, the sensor <NUM> can be used to verify whether the expected valve state corresponds to the actual valve state.

<FIG> and <FIG> show a schematic view of the solenoid valve <NUM> of the steam oven <NUM> of <FIG>. <FIG> shows the valve <NUM> in a closed state, and <FIG> shows the valve <NUM> in an open state.

The solenoid valve <NUM> comprises a solenoid <NUM> and a plunger <NUM> which are arranged such that the solenoid <NUM>, when powered, moves the plunger <NUM> from an extended position in which the plunger <NUM> extends into the pipeline <NUM> to block the passage of fluid therethrough, to a retracted position in which the plunger <NUM> is retracted from the pipeline <NUM> to permit the passage of fluid therethrough. <FIG> shows the plunger <NUM> in the extended position, and <FIG> shows the plunger <NUM> in the retracted position.

The solenoid <NUM> of the solenoid valve <NUM> is configured to receive power from the control unit <NUM> to energise the solenoid <NUM>. The control unit <NUM> therefore actuates the valve <NUM> by selectively powering the solenoid <NUM>. In this example, an "open" command signal transmitted by the control unit <NUM> to the valve <NUM> provides power to the solenoid <NUM> which causes the solenoid <NUM> to move the plunger <NUM> to the retracted position using electromagnetic forces, and a "closed" command signal transmitted by the control unit <NUM> to the valve <NUM> ceases power to the solenoid <NUM>.

The solenoid valve comprises a spring <NUM> arranged to bias the plunger <NUM> to the extended position. Thus, when there is no power to the solenoid <NUM>, the plunger <NUM> is urged into the extended position by the biasing action of the spring <NUM> (as shown in <FIG>). When there is power to the solenoid <NUM>, the force exerted by the solenoid <NUM> on the plunger <NUM> overcomes the spring force and causes the spring <NUM> to compress (as shown in <FIG>). In some examples, a different biasing member may be provided.

The solenoid valve <NUM> is a normally-closed valve since the spring <NUM> biases the plunger <NUM> to the extended position. A normally-closed valve can provide safety benefits since the water or steam is normally prevented from reaching the food preparation chamber, thus decreasing the risk of flooding in the oven.

The sensor <NUM> is arranged to detect whether the plunger <NUM> is in the retracted position or the extended position. The sensor <NUM> may comprise any suitable sensor type. Examples include optical sensor, magnetic sensor, ultrasonic sensor, etc. The most suitable type of sensor may depend on the type of valve being used.

In one illustrative example, the sensor <NUM> comprises an optical sensor <NUM> arranged such that, when the plunger <NUM> is in the retracted position, the plunger <NUM> blocks a light path of the optical sensor <NUM>, and when the plunger <NUM> is in the extended position, the plunger <NUM> does not block the light path of the optical sensor <NUM>. Thus, the sensor data will indicate that the actual valve state is an open state when the data corresponds to the light path being blocked, and the sensor data will indicate that the actual valve state is a closed state when the data corresponds to the light path not being blocked. In other examples the optical sensor <NUM> may be arranged oppositely, such that the plunger <NUM> being in the retracted position does not block a light path of the optical sensor <NUM>, and the plunger <NUM> being in the extended position blocks the light path of the optical sensor <NUM>.

The sensor <NUM> and the valve <NUM> are configured such that the detection of the actual valve state by the sensor <NUM> is independent of control of the valve <NUM> by the control unit <NUM>.

The actuation of the valve <NUM> by the control unit <NUM> is not based on the valve state detection by the sensor <NUM>. That is, the command signal transmitted by the control unit <NUM> to the valve <NUM> is independent of (e.g. is not based on and/or does not depend on) measurements by the sensor <NUM>. In some embodiments, the control unit <NUM> and/or the valve <NUM> may be electrically isolated from the sensor <NUM>. This is beneficial since the circuitry for controlling the valve actuation is then not a possible common cause of failure of the valve <NUM> and the sensor <NUM>.

In some embodiments the sensor <NUM> directly detects the physical location of the plunger <NUM>, rather than inferring the plunger location e.g. by monitoring the current in the solenoid <NUM>. This is because if the valve and the sensor are dependent on the same current, then in the case of a failure the sensor <NUM> would not be able to independently verify the valve state. In addition, such sensors can be costly and complex.

The valve <NUM> and the sensor <NUM> are configured to receive power from separate and independent (e.g. electrically isolated) power supplies (not shown). In examples in which the valve <NUM> receives power from the control unit <NUM>, e.g. in the form of command signals, the control unit <NUM> may be configured to receive power from a first power supply that is independent of a second power supply providing power to the sensor <NUM>. This can be advantageous since a failure of the first power supply would not affect operation of the sensor <NUM>, and a failure of the second power supply would not affect operation of the valve <NUM>, so that the power supply is not a possible common cause of failure of the valve <NUM> and the sensor <NUM>. The steam oven <NUM> may comprise the two power supplies for separately powering the valve <NUM> (and/or control unit <NUM>) and the sensor <NUM>.

The sensor <NUM> outputs sensor data about the actual valve state for processing. In some embodiments, the sensor <NUM> outputs the sensor data to a circuit board (not shown) located on or proximate to the valve <NUM>. The circuit board may comprise the sensor <NUM>, and may be arranged to receive and process the sensor data from the sensor <NUM> and output a signal indicative of the actual valve state based on the sensor data. In other embodiments, the sensor <NUM> is configured to transmit the sensor data to an electronics unit (not shown) which is located remotely from the valve <NUM>. The transmission may be wired or wireless, for instance. The remote electronics unit may process the sensor data and output a signal indicative of the actual valve state based on the sensor data.

The state of the valve <NUM> can be verified by comparing the actual valve state as measured by the sensor <NUM> to the expected valve state as expected based on the command signal from the control unit <NUM>. The steam oven <NUM> may comprise a verification circuit (not shown) configured to perform this comparison. The verification circuit may be configured to receive the signal indicative of the actual valve state based on the sensor data (e.g. from the circuit board or the remote electronics unit) and to receive a signal indicative of the expected valve state (e.g. from the control unit <NUM>), and to compare or cross-check the signals. It can then be verified whether the expected valve state corresponds to the actual valve state. If there is a discrepancy, this may indicate a fault with the valve <NUM> or the control unit <NUM>. The verification circuit may be part of the control circuitry for general operation of the steam oven <NUM>.

Claim 1:
A steam oven for an aircraft galley, comprising:
a pipeline (<NUM>) for supplying fluid comprising water or steam to a food preparation chamber (<NUM>) of the steam oven, the pipeline (<NUM>) being configured to receive water or steam from a source external to the steam oven;
a valve (<NUM>) configured to regulate the flow of said fluid through the pipeline (<NUM>), the valve (<NUM>) having an open state in which the valve (<NUM>) permits the flow of said fluid through the pipeline (<NUM>) and a closed state in which the valve (<NUM>) prevents the flow of said fluid through the pipeline (<NUM>); and
a control unit (<NUM>) configured to actuate the valve (<NUM>) between the open and closed states;
characterised in that:
the valve (<NUM>) comprises a sensor (<NUM>) configured to detect an actual state of the valve (<NUM>), the sensor (<NUM>) being independent of the control unit (<NUM>);
wherein the valve (<NUM>) and the sensor (<NUM>) are configured to receive power from separate and independent power supplies.