BR102013016869A2 - oxygen respiration device and methods for providing oxygen to a passenger and for maintaining an aircraft emergency oxygen system - Google Patents

Abstract

invention patent: "device for breathing oxygen and methods for supplying oxygen to a passenger and for maintaining an emergency oxygen system of an aircraft". The present invention relates to a device for breathing oxygen, comprising: an oxygen source (51), in particular a chemical oxygen generator or an oxygen pressure tank, at least one oxygen mask (55) connected via an oxygen supply line (2, 57) to said oxygen source (51), a flow control unit (52) adapted to receive a signal indicating ambient pressure or to detect ambient pressure and control The flow of oxygen through the oxygen supply line (2, 57) depends on said ambient pressure, the flow control unit (52) being adapted to provide a flow with low oxygen content in a first ambient pressure, supply a flow with high oxygen content at a second ambient pressure which is lower than said first ambient pressure and increase said oxygen flow in at least two steps, preferably increasing said oxygen flow constantly, an electronic passage valve (1) being arranged in the oxygen supply line (2, 57) and comprising a first flow path (3) and a second flow path (4) comprising a passageway (5) in a flow arrangement parallel to said first flow path (3), said electronic passage valve (1) being adapted to direct oxygen flow through said first flow path (3) at an ambient pressure above a predetermined level in accordance with the first flow condition and direct the oxygen flow through said second flow path (4) at an ambient pressure below a predetermined level according to the second flow condition, said first flow path (3) having a smaller flow cross section than said second flow path.

Description

Report of the Invention Patent for "OXYGEN BREATHING DEVICE AND METHODS FOR SUPPLYING A PASSENGER OXYGEN AND MAINTAINING AN AIRCRAFT EMERGENCY O-XYGEN SYSTEM". The present invention relates to an oxygen breathing device comprising an oxygen source, in particular a chemical oxygen generator or an oxygen pressure tank, at least one oxygen mask connected through a line of oxygen. oxygen supply to said oxygen source, a flow control unit adapted to receive an ambient pressure indicator signal or detect ambient pressure and to control oxygen flow through the oxygen supply line depending on said ambient pressure, at which The flow control unit is adapted to provide a low oxygen flow at a first ambient pressure, provide a high oxygen flow at a second ambient pressure that is less than the first ambient pressure, and increase said flow rate. oxygen in at least two steps, preferably to increase said oxygen flow constantly.

A further aspect of the invention is a method for providing oxygen to an aircraft passenger and a method for maintaining an aircraft emergency oxygen system.

In general, emergency oxygen supply systems intended for passengers of an aircraft are known. These systems are used to provide oxygen to passengers in the event of a cabin pressure drop or in other emergency or critical situations, where the oxygen present in the aircraft cabin is not sufficient for the vital functions of the passenger inside. from said cabin.

An emergency oxygen respirator is known from European patent application EP 2 143 469 A1. According to this reference, an oxygen respirator provides an oxygen flow from an oxygen source to a mask. of oxygen from a passenger or crew member. Oxygen flow is controlled by a control unit to ensure that the passenger is supplied with an exact amount of oxygen. The control unit receives pressure signals corresponding to ambient pressure from a pressure sensor and temperature signals corresponding to the oxygen temperature passing through the breathing device from a temperature sensor. In general, with such a device, it is possible to provide an amount of oxygen to a passenger in an emergency that ensures that the passenger receives sufficient oxygen to maintain all vital functions.

An important aspect of such oxygen breathing devices, however, is a desire to reduce the weight and size of such devices for the purpose of reducing the overall weight of the aircraft and providing additional space for entertainment systems or the like. However, reducing size and weight should not reduce the amount of time oxygen is supplied to a passenger. Correspondingly, an object of the invention is to provide an emergency oxygen system for passengers of an aircraft of reduced size and weight.

An additional aspect of known existing service systems is the need to periodically maintain these systems and adapt them to improved requirements or regulations in the aviation industry. During this maintenance, there is a desire to be able to refine known existing oxygen systems for the purpose of saving weight and / or space or to refine the characteristics of such systems in order to adapt them to existing requirements or regulations. A further object of the invention is to provide a method and device that allows for the improvement of existing maintenance procedures efficiently.

Another objective is to install modern oxygen masks that provide low oxygen consumption at altitudes between 4,570 and 9,140 meters (15,000 and 30,000 feet). Therefore, the oxygen flow at these altitudes needs to be adapted accordingly.

These and other objectives are achieved by an oxygen respiration device according to the introductory function having an oxygen source, in particular a chemical oxygen generator or an oxygen pressure tank, at least one oxygen mask connected through an oxygen supply line to said oxygen source, a flow control unit adapted to receive a signal indicating ambient pressure or to detect ambient pressure and to control oxygen flow through the oxygen supply line depending on said ambient pressure. wherein the flow control unit is adapted to provide low oxygen flow at a first ambient pressure, provide a high oxygen flow at a second ambient pressure that is less than said first ambient pressure and increase said oxygen flow in at least two steps, preferably increasing said oxygen flow constantly, wherein an electronic bypass valve is disposed on the oxygen supply line and comprises a first flow path and a second flow path comprising a passage channel in a flow arrangement parallel to said first flow path, in said electronic flow valve is adapted to direct oxygen flow through said first flow path at an ambient pressure above a predetermined level according to a first flow condition and direct oxygen flow through said flow path. flow at an ambient pressure below a predetermined level according to a second flow condition, wherein said first flow path has a flow cross section less than said second flow path. The oxygen breathing device provides a weight-saving means for passenger lifesaving features in an aircraft. The device can be integrated into existing oxygen breathing systems without the need to redesign such existing systems. In addition, the oxygen breathing device according to the invention is adapted to be used in currently used oxygen masks providing reduced oxygen consumption. Thus. a reduction in the overall weight of the sisterry can be obtained.

Preferably, the first ambient pressure is a system pressure corresponding to an aircraft altitude below 9,140 meters (30,000 feet), for example, intermediate altitudes between 4,570 and 9,140 meters (15,000 and 30,000 feet). It is further preferred that the second ambient pressure be a system pressure corresponding to an aircraft altitude of more than 9,140 meters (30,000 feet). The term smaller flow cross section reflects the fact that a smaller amount of oxygen per unit of time can flow through the first flow path compared to the second flow path.

According to a first preferred embodiment, said first flow path comprises a calibrated orifice. In this way a predetermined maximum amount of oxygen flow to the passenger can be achieved. Preferably, the calibrated orifice may be a channel with a predetermined cross section which is disposed in the first flow path so that oxygen flowing through the first flow path needs to flow through the calibrated orifice. Depending on the cross section, the maximum oxygen flow to a passenger or crew member may be adjusted.

If the amount of oxygen entering the electronic bypass valve exceeds the amount of oxygen exiting the electronic bypass valve due to the calibrated port, the pressure in the oxygen supply line increases. This pressure increase can be used as a signaling condition for the electronic bypass valve to switch to the second flow condition.

According to an additional embodiment, said first flow path consists of a flow only through a calibrated orifice and said second flow path consists of a flow only through said passage channel or said passage channel and said flow path. calibrated hole. This provides a flexible and reliable mode of oxygen delivery to the passenger.

An additional preferred embodiment is characterized in that said electronic bypass valve comprises a first flow channel comprising a hole with a predetermined cross section and a second flow channel, wherein a spring oriented valve member engages a base. valve pressure and a pressure within the oxygen supply line acting against said spring to switch the valve member to switch the electronic passage valve between said first and said second flow conditions. This provides an automatic and controlled form of pressure to switch the electronic flow valve between the first and second flow condition. The spring-oriented valve member preferably comprises an adjustable spring comprising an adjusting screw which may be mounted in an electronic bypass valve housing. By adjusting the screw, the spring load and hence the pressure within the oxygen supply line that is insufficient to lift the valve member can be adjusted.

In another preferred embodiment, a plurality of oxygen masks are connected to said oxygen source via a pipeline, the oxygen supply line comprises a first section of central oxygen line that directs oxygen from the oxygen source to said one. tubing and a plurality of second oxygen line sections each directed oxygen from the tubing to an oxygen mask, said electronic bypass valve arranged in a flow direction between said flow control unit and the said oxygen masks. This provides a central supply of oxygen from the oxygen source to the plurality of oxygen masks.

In another embodiment, said electronic bypass valve is arranged in said first central oxygen line section, in particular, in a flow direction between said flow control unit and said pipeline. This provides additional weight savings as an electronic centralized bypass valve is provided for a plurality of oxygen masks, that is, for the oxygen supply of a plurality of passengers.

A further embodiment of the above-mentioned oxygen breathing device comprises a plurality of electronic bypass valves, wherein at least a number of said plurality of second oxygen line sections comprises one of said plurality of electronic bypass valves. In this way a decentralized arrangement of the electronic bypass valves is obtained which provides increased liability for the oxygen breathing device. If one of the electronic bypass valves does not function satisfactorily, which would lead to a malfunction of the oxygen supply to one of the oxygen masks, the other remaining between the oxygen masks will still function satisfactorily. In such an emergency, two passengers are able to share an oxygen mask.

According to a further embodiment of the oxygen breathing device, said electronic bypass valve comprises a first and a second calibrated orifice, said second calibrated orifice having a flow cross-section greater than said first calibrated orifice. that in said first flow condition oxygen is flowing through said first calibrated orifice and in said second flow condition oxygen is at least partially evading said first calibrated orifice and is flowing through said second calibrated orifice. This provides a predetermined maximum oxygen flow in the second flow condition. In this way, the oxygen flow to the passenger's breathing mask can be calibrated for both the first and second flow conditions. Therefore, there is no need for an additional calibrated orifice provided in the passenger's breathing mask.

According to a further embodiment of the breathing device, in said second flow condition a first art of oxygen is flowing through said first calibrated orifice and a second part of oxygen is flowing through a passage channel disposed parallel to said first. calibrated hole.

According to another embodiment, in said first flow condition oxygen is flowing through said first and said second orifices calibrated in a serial arrangement. This provides a space-saving design of the electronic bypass valve with a simplified design.

In another embodiment of the oxygen breathing device, said electronic bypass valve comprises a housing having an inlet opening and an outlet opening, wherein a first flow channel connects said inlet opening and said outlet opening, wherein a second flow channel connects said inlet opening and said outlet opening to a valve piston sealing against a valve base within said housing, wherein when said valve piston is in sealing contact at said valve base, the second flow channel is interrupted, thereby requiring oxygen flowing through the electronic flow valve from the inlet port to the outlet port to flow through said first flow channel, and whereby when said valve piston is at a distance position without contact with said valve base, the second flow channel is opened, thereby allowing the Oxygen flowing through the electronic flow valve from the inlet opening to the outlet opening flows through said first and said second flow channels. This results in a reliable electronic bypass valve with a simple design.

According to another embodiment of the above-mentioned oxygen breathing device, a first calibrated orifice is disposed in the first flow channel and a second calibrated orifice is disposed in the second flow channel, said first calibrated orifice having a flow cross section. smaller than said second calibrated hole. This provides a flow of oxygen to the passenger in the second flow condition that is greater than the flow of oxygen to the passenger in the first flow condition.

According to a further embodiment of the above-mentioned oxygen breathing device, said piston is hollow, the first and second flow channels extend through said piston and said second calibrated orifice is disposed in the piston. In this way, a space-saving design of the electronic bypass valve is obtained.

A further aspect of the invention is a method for providing oxygen to a passenger of an aircraft comprising the steps of; - supply oxygen from an oxygen source to at least one oxygen mask, - automatically control oxygen by a flow control unit • by receiving a signal indicating ambient pressure or by detecting ambient pressure • by controlling oxygen flow through the oxygen supply line depending on said ambient pressure, wherein a low oxygen flow is provided at a first ambient pressure, and a high oxygen flow is provided at a second pressure. less than said first ambient pressure • thereby said oxygen flow is increased by at least two steps, preferably constantly, characterized by the fact that - pxigen is directed from said oxygen control unit. flow to said oxygen mask via an electronic flow valve comprising a first flow path and a second path a flow channel comprising a flow channel in a flow arrangement parallel to said first flow path, - switching said electronic flow valve to direct oxygen flow through said first flow path at an ambient pressure above a predetermined level according to the first flow condition and directing oxygen flow through said second flow path at an ambient pressure below a predetermined level according to a second flow condition, said first path being The flow path has a flow cross-section smaller than said second flow path.

Another aspect of the invention is a method for maintaining an emergency oxygen system of an aircraft, said emergency oxygen system comprising; - an oxygen source, in particular a chemical oxygen generator or an oxygen pressure tank, - at least one oxygen mask connected via an oxygen supply line to said oxygen source, - an oxygen control unit. flow adapted to receive a signal indicating ambient pressure or to detect ambient pressure and to control oxygen flow through the oxygen supply line depending on said ambient pressure, and the flow control unit is adapted to provide a flow low oxygen at a first ambient pressure, • provide a high oxygen flow at a second ambient pressure that is less than said first ambient pressure, and • increase said oxygen flow by at least two steps, preferably increasing said oxygen flow constantly, characterized by the steps of installing an electronic bypass valve on said supply line of oxygen, wherein the electronic flow valve comprises a first flow path and a second flow path comprising a flow channel in a flow arrangement parallel to said first flow path, said electronic flow valve It is adapted to direct oxygen flow through said first flow path at an ambient pressure above a predetermined level according to a first flow condition and direct oxygen flow through said second flow path at a pressure. below a predetermined level according to a second flow condition. Wherein said first flow path has a smaller flow cross-section than said second flow path.

Preferred embodiments of the invention are described in accordance with the figures, wherein Figure 1 is a first embodiment of a side view electronic valve in accordance with the present invention; Figure 2 is a second embodiment of a valve. electronics in a side view according to the present invention. Figure 3 is a first embodiment of a device for oxygen respiration in a schematic view according to the present invention. Figure 4 is a second embodiment of a device for Oxygen respiration in a schematic view according to the present invention: and Figure 5 is a third embodiment of a schematic view oxygen respiration device according to the present invention. Figure 1 shows an electronic bypass valve 1 disposed on an oxygen supply line 2 comprising a first flow path 3 and a second flow path 4. Electronic passage valve 1 may preferably be positioned in a flow direction next to a passenger oxygen mask not shown in Figure 1. The second flow path 4 comprises a flow channel 5 in a flow arrangement parallel to the first flow path 3. The electronic flow valve 1 is adapted to directing an oxygen flow 6 through said first flow path 3 at an ambient pressure above a predetermined level according to a first flow condition, i.e. a system pressure corresponding to an aircraft altitude below 9,140 meters (30,000 feet). Therefore, at intermediate altitudes, for example, 4,570 and 9,140 meters (15,000 to 30,000 feet), the second flow path 4 of the electronic bypass valve 1 is closed.

Additionally, the electronic flow valve 1 is adapted to direct oxygen flow 6 through said second flow path 4 at an ambient pressure below a predetermined level according to the second flow condition, i.e. a system pressure corresponding to an aircraft altitude above 30,000 feet (9,140 meters). The first flow path 3 comprises a calibrated orifice 7 which has a flow cross section smaller than the second flow path 4 when it is open. At intermediate altitudes, the calibrated orifice 7 reduces the effective flow of oxygen to the passenger's mask. The electronic flow valve 1 comprises a first flow channel 10 which serves as the first flow path 3. The second flow path 4 consists of a second flow channel 11, wherein a spring oriented valve member 12 enters contact with a valve base 13 when the second flow path 4 is closed. A pressure within the oxygen supply line 2 acts against a spring 14 to engage the valve member 12 to switch the electronic bypass valve 1 between a first and a second flow condition. That is, orifice 7 is calibrated so that at a predetermined inlet pressure, valve member 12 is raised against spring force 14. Thereby, second flow path 4 is opened. Spring load 14 may be adjusted by an adjusting screw 15 which is mounted in an electronic bypass valve housing 20. In an alternative embodiment of the electronic bypass valve 1, the valve member 12 de-sign may also be be performed by a membrane arrangement. The second flow channel 11 comprises a calibrated port 21 with a cross section that is larger than the cross section of the calibrated port 7. Figure 2 shows an electronic bypass valve 30 disposed on an oxygen supply line 31 comprising a first flow channel 32 and a second flow channel 33. The second flow channel 33 comprises two flow channels 34 and 35 in a flow arrangement parallel to the first flow channel 32. The electronic flow valve 30 is adapted to direct a oxygen flow 36 through said first flow channel 32 at an ambient pressure above a predetermined level, that is, a system pressure corresponding to an aircraft altitude below 9,140 meters (30,000 feet). The first flow channel 32 comprises a calibrated orifice 37 which provides a certain oxygen flow at a certain pressure in an inlet 42 DA of the electronic bypass 30.

In a flow direction behind the calibrated port 37 the electronic bypass valve 30 comprises a piston 40 with a valve base 41 which is closed when the oxygen pressure at the inlet 42 of the electronic bypass valve is less than a predetermined pressure value. . The piston 40 will be raised against a spring force 43 when the inlet pressure exceeds the predetermined value. The spring load 43 may be adjusted by an adjusting screw not shown in Figure 2 which is mounted in a housing 47 of the electronic bypass valve 30. Then, oxygen flows through the first flow channel 32 and additionally through second flow channel 33, i.e. through flow channels 34 and 35. Thus, increased oxygen flow 45 is achieved at an outlet 46 of electronic flow valve 30 adapted to direct oxygen flow 45 to a passenger oxygen mask not shown in Figure 2. Piston 40 is hollow and a second calibrated bore 46 is disposed on piston 40 in an oxygen flow direction behind the first and second flow channel 33. The electronic bypass valve 30 is encapsulated by housing 47 comprising an inlet port 48 and an outlet port 49. Oxygen flowing from the inlet port 48 to the outlet port 49 passes through the port. 37 and further through orifice 46 in a first flow condition. Port 46 has a larger cross-section than port 37. In a second flow condition, oxygen flowing from inlet port 48 to outlet port 49 passes through port 37, additionally through channels 34 and 35. and then through orifice 46. Figure 3 shows a first embodiment of an oxygen respirator 50 in a schematic view comprising an oxygen source 51. Oxygen source 51 may be a high pressure gaseous oxygen source or a source of chemical oxygen. Pressurized oxygen supplied by oxygen source 51 enters flow control unit 52 which includes a regulating valve. Flow control unit 52 controls the outflow pressure of the oxygen flow to be supplied to an electronic flow valve 53 arranged in a flow direction behind flow control unit 52. Flow control depends on the altitude of the aircraft. that is, flow control unit 52 receives a signal indicating ambient pressure and correspondingly controlling oxygen flow. Preferably, the flow control unit outlet pressure 52 is a suitable system and / or breathing pressure. At an increased altitude, the flow control unit 52 increases the oxygen pressure to be supplied to the electronic check valve 53. The electronic check valve 53 can be an electronic check valve substantially the same as the electronic check valve as described. Figure 1. The oxygen respirator 50 further comprises a piped distribution network 54 for distributing oxygen flow to a series of passenger oxygen masks 55. Calibrated holes 56 are disposed next to the oxygen masks 55 in an oxygen flow direction next to each oxygen mask 55. Oxygen source 51, flow control unit 52, electronic bypass valve 53, and oxygen masks 55 are connected via a line. 57. Oxygen supply line 51 includes a first section of central oxygen line. 58 which directs oxygen from oxygen source 51 to line 54 and a plurality of second oxygen line sections 59 each directing oxygen from line 54 to an oxygen mask 55. Figure 4 shows a second One embodiment of an oxygen breathing device 60 similar to an oxygen breathing device 50 as shown in Figure 3. The oxygen breathing device 60 comprises an oxygen source 51, a flow control unit 52 and a series of decentralized electronic bypass valves 61 arranged in a distribution network 62 comprising the pipes 63. The electronic bypass valves 61 are supplied with oxygen through an oxygen supply line 64 which includes a first section of central oxygen line 65 and a series of second sections of oxygen line 66. The dimensions of the electronic bypass valves 61 are smaller than the dimensions of the electronic bypass valve 53 shown in Figure 3. Figure 5 shows a third embodiment of an oxygen breathing device 70 similar to the oxygen breathing device 60 as shown in Figure 4. The device for oxygen respiration 70 comprises an oxygen source 51, a flow control unit 52 and a plurality of combined electronic overflow valves 71, similar to electronic overflow valve 30 as described in Figure 2. Combined electronic overflow valves 71 are arranged in an oxygen flow direction next to each passenger oxygen supply mask 72. The calibrated holes 73 for controlling the flow of oxygen to the passenger are integrated into one of the combined electronic flow valves 71. The dimensions of the electronic check valves 71 are smaller than valve dimensions electronic check valves 53 shown in Figure 3 and the electronic check valves 61 shown in Figure 4.

Claims (15)

1. An oxygen breathing apparatus, comprising: - an oxygen source (51), in particular a chemical oxygen generator or an oxygen pressure tank, - at least one oxygen mask (55) connected via a oxygen supply line (2, 57) to said oxygen source (51), - a flow control unit (52) adapted to receive a signal indicating ambient pressure or detecting ambient pressure and controlling oxygen flow through the oxygen supply line (2, 57) depending on said ambient pressure, the flow control unit (52) being adapted to • provide a low oxygen flow at a first ambient pressure, • provide a high oxygen flow at a second ambient pressure that is less than said first ambient pressure; and • increasing said oxygen flow in at least two steps, preferably increasing said oxygen flow constantly, characterized by an electronic bypass valve (1) disposed in the oxygen supply line (2, 57) and comprising a first flow path (3) and a second flow path (4) comprising a flow channel (5) in a flow arrangement parallel to said first flow path (3), said electronic flow valve being adapted to direct oxygen flow through said first flow path (3) at an ambient pressure above a predetermined level according to the first flow condition; and directing oxygen flow through said second flow path (4) at an ambient pressure below a predetermined level according to a second flow condition, said first flow path (3) having a section flow cross-section smaller than said second flow path (4). Oxygen breathing device according to claim 1, characterized in that said first flow path (3) comprises a calibrated orifice (7). Oxygen respiration device according to claim 1 or 2, characterized in that said first flow path (3) consists of a flow only through a calibrated orifice (7) and said second flow path. flow (4) consists of a flow only through said through channel (5) or said through channel (5) and said calibrated orifice (7). Oxygen breathing device according to any one of claims 1 to 3, characterized in that - said electronic flow valve (1) comprises a first flow channel (10) comprising an orifice (7) with a predetermined cross-section and a second flow channel (11), wherein a spring-oriented valve member (12) engages a valve base (13) and a pressure within the oxygen supply line (2,57). acting against said spring to switch the valve member (12) to switch the electronic bypass valve (1) between said first and said second flow condition. Oxygen breathing device according to any one of claims 1 to 4, characterized in that - a plurality of oxygen masks (55) are connected to said oxygen source (51) via a pipe (54 ), - the oxygen supply line (2, 57) comprises a first central oxygen line section (58) that directs oxygen from the oxygen source (51) to said tubing (54) and a plurality of second oxygen line sections (59) each directing oxygen from the tubing (54) to an oxygen mask (55), - said electronic bypass valve (53) is arranged in a flow direction between said unit flow control (52) and said oxygen masks (55). Oxygen breathing device according to any one of claims 1 to 5, characterized in that - said electronic bypass valve (53) is disposed in said first central oxygen line section (58) in accordance with the invention. particular, in a flow direction between said flow control unit (52) and said piping (54). Oxygen breathing device according to claim 6, characterized in that it comprises a plurality of electronic bypass valves (61), at least one of said plurality of second oxygen line sections (66). ) comprises one of said plurality of electronic bypass valves (61). Oxygen breathing device according to any one of claims 1 to 7, characterized in that said electronic flow valve (1) comprises a first and a second calibrated orifice, said second calibrated orifice having a flow cross-section larger than said first calibrated orifice, wherein in said first flow condition oxygen is flowing through said first calibrated orifice; and in said second flow condition oxygen is at least partially evading said first calibrated orifice and is flowing through said second calibrated orifice. Oxygen breathing device according to claim 8, characterized in that in said second flow condition a first part of oxygen is flowing through said first calibrated orifice and a second part of oxygen is flowing through a passage line disposed parallel to said first calibrated orifice. Oxygen breathing device according to claim 8 or 9, characterized in that - in said first flow condition oxygen is flowing through said first and said second orifice calibrated in a serial arrangement. Oxygen breathing device according to any one of claims 1 to 10, wherein said electronic pressure relief valve 12. Claim missing in original document. 13. - said second calibrated hole (46) is disposed in the piston (40) A method of providing oxygen to an aircraft passenger, comprising the steps of: - supplying oxygen from an oxygen source to at least one oxygen mask, - automatically controlling oxygen by a flow control unit (52) upon receiving a signal indicating ambient pressure or detecting ambient pressure; and controlling oxygen flow through the oxygen supply line (2, 57) depending on said ambient pressure, where a low oxygen flow is provided at a first ambient pressure, and a high oxygen flow. it is provided at a second ambient pressure that is less than said first ambient pressure • thus said oxygen flow is increased in at least two steps, preferably constantly, characterized by the fact that - oxygen is directed from said flow control unit (52) to said oxygen mask (55) via an electronic flow valve (53) comprising a first flow path (3) and a second flow path (4) comprising a passage channel (5) in a flow arrangement parallel to said first flow path (3), - switching said electronic passage valve (1) to direct oxygen flow through the said first flow path (3) at an ambient pressure above a predetermined level according to the first flow condition; and directing the oxygen flow through said second flow path at an ambient pressure below a predetermined level according to a second flow condition, said first flow path (3) having a flow cross section. less than said second flow path (4). A method for maintaining an emergency oxygen system of an aircraft, wherein said emergency oxygen system comprises: - an oxygen source (51), in particular a chemical oxygen generator or an oxygen pressure tank. , - at least one oxygen mask (55) connected via an oxygen supply line (2, 57) to said oxygen source (51), - a flow control unit (52) adapted to receive a signal that indicates ambient pressure or sensing ambient pressure and controlling oxygen flow through the oxygen supply line (2, 57) depending on said ambient pressure, and the flow control unit (52) is adapted to provide • a low oxygen flow at a first ambient pressure, • provide a high oxygen flow at a second ambient pressure that is less than said first ambient pressure; and increasing said oxygen flow in at least two steps, preferably increasing said oxygen flow constantly, characterized by the steps of installing an electronic bypass valve (1) in said oxygen supply line (2, 57). wherein the electronic bypass valve (1) comprises a first flow path (3) and a second flow path (4) comprising a passage channel (5) in a flow arrangement parallel to said first flow path (3), wherein said electronic bypass valve is adapted to direct oxygen flow through said first flow path (3) at an ambient pressure above a predetermined level according to a first flow condition; directing oxygen flow through said second flow path (4) at an ambient pressure below a predetermined level according to a second flow condition, wherein said The first flow path (3) has a flow cross section smaller than said second flow path (4).