EP1555043A2 - Device for the supply of mixed gas in a closed loop breathing system - Google Patents

Abstract

The closed circuit breathing apparatus using a gas mixture, for use by firefighters and divers, has a gas mixture flow (23) through an automatic valve (22) to keep the electrical and electronic components dry at the connection side (3) of the gas sensors (1), before it passes through an equalizing unit (31) in the breathing circuit (29,30). The automatic valve prevents the development of an underpressure in the antechamber (34), and the equalizing unit prevents an overpressure and backflow of moist breathing gas from the breathing circuit. The pressure equalizing at the gas sensors is maintained by their membranes, linked to the antechamber through the connection openings.

Description

Technical area

Modern circulatory respirators for use in civil protection, at the fire department or underwater use as Respiratory gas instead of pure oxygen a mixed gas. Here is to Monitoring the oxygen dosage of the use of oxygen sensors appropriate. In addition, carbon dioxide sensors can also be used to be available. The long-term reliable use requires such electrical gas sensors due to the Moisture in the breathing circuit Protective measures to ward off the Condensation on electrical and electronic components of the Breathing apparatus.

State of the art

FIG. 1 shows the simplified basic structure of a Mixed gas - Kreislaufatemgerätes according to the prior art Technology [1] [2] [3] [4].

Starting with the counterlung (12) in the upper part of the figure passes the regenerated breathing gas contained therein (30) over an inhalation tube (13) to a mouthpiece unit (14). In these are flutter valves included, not shown, the imposing the indicated direction on the respiratory gas circulation. about the exhalation tube (15) passes the exhaled, spent Breathing gas (28) into a soda lime cartridge (16). The one in it located soda lime, shown as spheres, withdraws from the Respiratory gas carbon dioxide and binds it chemically. The from the Carbon dioxide largely liberated and from the Atemkalkpatrone originating breathing gas (29) enters a mixing chamber (17), where a Mixing process takes place to increase the oxygen content of the To bring the breathing gas to a setpoint.

The device for mixing gas supply into the breathing circuit is mostly from an automatic valve for mixed gas (22), the one from a compressed gas tank originating and under one Medium pressure gas mixture (21) is supplied. Of the associated compressed gas tank and the pressure reducer are off For clarity, not shown.

The gas mixture usually exists in the case of diving equipment one or more inert gases, such as helium or nitrogen, and a small proportion of oxygen which is such that even at the maximum depth of a physiological dangerous too high oxygen partial pressure does not occur can. For mixed gas breathing apparatus for atmospheric conditions is used as a gas mixture ordinary largely dried and used oil-free compressed air.

The automatic valve (22) is usually as lung automatic Valve designed via a diaphragm (24) is controlled. When in the respirator, a relative negative pressure relative to the ambient pressure prevails, then presses the membrane (24) using a lever mechanism, a spring together and lifts the Valve from the valve seat, whereby the supplied to (21) Gas mixture at (23) flows into the mixing chamber (17). As soon as Pressure equalization is made, the spring pushes the diaphragm back to the starting position and the valve closes again. This will ensure that the user regardless of the degree of filling of the counterlung always a full Take a breath out of the device. When diving equipment is Moreover, when diving always a relative negative pressure in the Breathing circuit avoided without the user has to intervene.

Instead of the automatic valve is known in some Respiratory equipment a manually operated valve for mixed gas supply used, but this complicates the operation of the breathing apparatus and is therefore disadvantageous.

In the breathing circuit can - especially in diving equipment at Emerge - a relative overpressure arise. It is known, at one point of the breathing circuit an automatically acting pressure relief valve, which is an overpressure in Derives breathing circuit to the outside. Discharge of overpressure through the nose is cheaper and more reliable, which is why in the Figures on the representation of such an optional Overpressure valve was omitted.

The components described so far are not enough to always a sufficient oxygen content in the breathing circuit sure. For this purpose, an additional metering valve for Oxygen (19) responsible, the one from a compressed gas tank originating and under a medium pressure standing oxygen gas (18) is supplied. The associated compressed gas tank and the Pressure reducers are not for reasons of clarity shown.

In electronically controlled self-mixing breathing apparatus with closed circuit [1] [2] [3] [4] the metering valve (19) controlled by a measurement of the oxygen partial pressure, by means of electrochemical gas sensors (1), which in the mixing chamber (17) are arranged. Some former respirators had housed the gas sensors in the counterlung, which is disadvantageous because the sensors there in position changes of Condensation can be drowned suddenly. The signals of Gas sensors arrive via electrical lines (25) to a Evaluation electronics (26), which in case of need via a electrical control line (27) the metering valve (19) activated.

When this opens, oxygen derived from it (20) into the mixing chamber.

In half-closed Kreislaufatemgeräten [6] is from the Dosing valve (19) a constant gas flow from a mixed gas instead of oxygen passed into the breathing circuit, and the Surplus is regularly over an automatically acting Relief valve drained into the environment. Although this requires Type of recirculation breathing devices in principle no Measurement of the oxygen partial pressure, in case of a malfunction of the Dosage - for example, by a dirt in the Dosing nozzle arrives and these partially blocked - the Users of the device, however, without any warning. That's why in semi-closed Kreislaufatemgeräten monitoring the Oxygen partial pressure by gas sensors appropriate. The Evaluation electronics (26) then proposes to lower or Exceeding limits only alarm, and the electrical control line (27) to the metering valve (19) deleted.

In both types of respirators is known by these Ensure that the devices from the mixing chamber in the counterlung inflowing regenerated breathing gas (30) always a physiologically perfect oxygen partial pressure having. An accident in the dosage can be fatal. Just in rebreathers cause unconsciousness or Loss of control due to incorrect oxygen dosage regularly to fatal accidents. This results in the Demand for the greatest possible reliability of dosing and Monitoring process. In the professional world this topic is extreme controversial. There are groups that have every kind of electronics in the world Dosage almost dogmatically reject. Others say there is no problem, you can with waterproof coatings and Coatings and waterproof connection cables and Cable penetrations get along. This floats above all Manufacturers of such breathing apparatus the sword of Damocles Product liability. The extent of the product liability problem in the technical and historical context is short in the following because it is one of the main motivations that to applicant's inventive step in the field has led the Kreislaufatemgeräte.

First electronically controlled self-mixing rebreather came in the late 1960s in the under Designation "Electrolung" [1] in small numbers on the Market. At first enthusiastic as a revolution in scuba diving celebrated, they were after three fatal accidents in the years 1970 to 1971, two of which were due to incorrect operation of the device and was left unanswered by the manufacturer taken from the market, as the difficult product liability situation one long-term commercial success has been questioned. For the following decades remained electronically controlled self-mixing rebreathers are a domain of the military, in the form of the Mk 15 / Mk 16 diving equipment of the US Navy. The Basic patent for those can be found in [2], one further developed form with exchangeable breathing circuit in [3]. Only recently have electronically controlled self-mixing rebreathers according to [4] increased in the Hands of scuba divers, with corresponding accident numbers [5], as if to repeat the story. electronic Controlled self-mixing rebreathers are also included disputed with some forces. The German Federal Navy has been using a semi-closed rebreather for decades with Konstantflußdosierung a [6], and has in Recently, instead of electronically controlled self-mixers Successor device procured, whose dosing system also pure works mechanically.

A major reason for this restraint is that too in professional circles are justified doubts whether Gas sensors, their electrical leads and their Evaluation electronics as well as an electrical dosing valve in Moist interior of a recirculation breathing apparatus in the long term can be reliably operated without it now and then suddenly comes to dangerous dysfunction. As a root This evil is caused by the always humid breathing gas Condensation viewed on the inner parts of the respirator.

An example of the extent of condensation can be found in [7] on a photo from the sensor chamber of a device according to [4]. If this is as harmless as claimed in the photo text, can be doubted, because usually designers are attacking from circulatory breathing apparatus to elaborate measures to the Condensation wet at least from the gas sensors and their Keep away from electrical leads, and they hold the Problem of condensation therefore certainly not so harmless like the journalists who with [7] obviously one Have written promotional articles. In this light are too See statements from dive operators about this unit have purchased and now want to rent for a profit. The public opinion is given the numerous deaths [5] split and there are also very critical voices.

It is not the task of this patent application, beyond the possible Speculating the outcome of ongoing court cases. The sole purpose of these statements is to clarify that the applicant regardless of the technical qualities this or similar diving equipment exactly in this Problem sees the decisive obstacle to that electronically controlled self-mixing rebreathers not yet in the market for scuba divers significant quantities could enforce, because even with best quality of construction and manufacture of There will always be accidents, and some will it will be deadly. This is inevitable in the Nature of diving. A human being is not fish and Underwater, he is in himself for him deadly environment. And if the misfortune strikes, then should The device manufacturer must be able to serve the court a perfect working principle to prevent the consequences of Condensation on the electrical and electronic Components of the diving device, whose function is so simple and so clear is that they are spiritual even by lawyers comprehended and understood. At the lowest Doubt threatens a lengthy and grueling Examination with appraisers and counter-appraisers. For the long-term economic success is the latter rather hindrance.

The prior art knows various Wirkprinzipien to solve the condensation problem to the electrical and electronic components of the gas sensors.

The most obvious solution, even now and then by laymen in the Internet would be a watertight casting of the rear connection opening of the gas sensor with a Resin after the sensor is installed in the respirator and connected. Unfortunately, this is when using commercial gas sensors [8], one of them as an example in Figure 2 shown, not allowed.

It turns out that the gas sensor (1) a Gas-sensitive front (2) has, at the one sensitive diffusion membrane is located (not shown), while its backside with the electrical connections (4) an opening (3) which may not be closed, because below the circuit board (5) sits one Pressure compensation diaphragm (7), which for the pressure equalization of Electrolyte chamber (6) is necessary. On the back Connection opening (3) of the gas sensor must be secured its correct function essentially the same pressure prevail as on its gas sensitive front (2). Becomes this pressure equalization obstructs, such as through watertight Potting the back of the sensors with a synthetic resin, then the pressure equalization of the electrolyte chamber takes place Deformation of the sensitive diffusion membrane at the gas-sensitive front, which directly leads to measurement errors and long term leads to failure of the gas sensor. It can also in commercial gas sensors of the illustrated type hardly succeed, the pressure compensation chamber (10) between the Circuit board (5) and the pressure compensation diaphragm (7) completely shed, as in the circuit board usually only there are a few small holes, mostly Through-holes of printed conductors, or bare Component positions that just barely for pressure equalization the pressure compensation chamber through a gaseous medium suffice. Remains in the pressure compensation chamber incomplete casting even a small cavity, then arises just when diving equipment when diving into it relative negative pressure, which is the seal of the pressure compensating diaphragm (8) causes leaks, especially as this seal usually only with a pressed-in metal ring (9) is fixed. By such a leak then passes the aggressive Electrolyte fluid to the circuit board and zerfrisst their Tracks and soldered electronic components. A sudden failure of the gas sensor is the result.

It is hereby shown that a casting commercially available Gas sensors of the illustrated design to ward off the Condensation on the electrical and electronic components the gas sensors is not possible. It has to turn on the gas sensors its rear opening (3) always a gas for pressure equalization be fed, which has substantially the same pressure like the gas to be analyzed at its gas sensitive Front side (2). It should as possible no moisture and no condensation on the electrical and electronic Get components of the gas sensors. Especially at Diving equipment is not trivial to solve this task.

The historical diving device according to [1] used polarographic Oxygen sensors, there Figure 3, the no pressure compensating diaphragm required. Here could the electrical supply lines the sensors and the evaluation electronics completely be sealed waterproof. The disadvantage was that this Sensors from each dive add a new electrolyte fill needed, and the successful placement of the diffusion membrane without inclusion of gas bubbles needed a special Technique, skillful fingers, and utmost cleanliness, no To introduce foreign ions. Surrounded on a staggering boat from salty sea air this was an almost insoluble one Task.

Later scuba diving equipment [2] [3] [4] use without exception commercial oxygen sensors in the above Design with a pressure compensation diaphragm, which over the Rear opening of the sensors a pressure equalizing gas is accessible. There are currently no other types of Oxygen sensors known for an autonomous breathing apparatus would be more appropriate, and this complication not with to bring oneself.

The diving equipment according to [2] [3] try the solution of the Condensation problem thereby, by the soda lime around the Gas sensors is arranged around. The principle of action exists here in it, the exothermic reaction of soda lime to warm up the Gas sensors to be used, which are lapped by the breathing gas. By the warming will be below the dew point at the electrical and electronic components, including theirs Connecting cables, prevented. However, this working principle is not explicitly mentioned in [2] [3], though the whole peculiar design of the device is derived from it. Condensation at the critical parts is avoided as long as the soda lime has a sufficient temperature. In the Warm-up and after the dive, unfortunately, still occurs minor and therefore not immediately dysfunctional Condensation on, however, over the long term as a strand acting connection lines in the below the sensor chamber encapsulated in the housing so-called "Horseshoe" - PCB forced out. After some time these are corroded and the The housing part concerned must be replaced. Also the US Navy feels the resulting maintenance costs as too expensive. However, these devices are subject to correct maintenance, So timely replacement of corrosion-prone parts, as reliable and they are proven in military use. Because of the peculiar shape are devices that called the Use the principle of action to solve the condensation problem, expensive to manufacture. Also a variant with separable breathing circuit [3], the rest of the device can then be rented at a dive center will not bring the necessary commercial success Cheapening.

For private users to enforce commercially so far only the much cheaper device according to [4], in which a Condensation on the electrical and electronic components the gas sensors and other parts of the metering device in accepted literally in the true sense of the word. The Extent of this condensation is shown in the photo [7]. Like from the Photo shows are intended to sealing measures water-repellent coatings ("conformal coating"), Plastic caps over the electrical connections Gas sensors, waterproof cabling, and others in [4] the measures outlined are the electrics and electronics before the Protect against condensation and prevent malfunctions. But the plastic caps can but the pressure equalization of Gas sensors hinder, what with rapid changes in depth too Incorrect measurements, which causes some users are to provide the caps with a small hole. But then condensation wetness can penetrate there again. If such unauthorized tinkering the cause of the There are numerous deaths [5], but not here be speculated. Anyway, the manufacturer of the device has the Problem in product liability lawsuits a court the Proof of proper functioning of his diving equipment. In which chosen working principle to ward off the condensation is that naturally rather difficult.

Another well-known principle of action to ward off condensation in respiratory equipment is the gas intended for analysis in a drying device to dry before the des gas-sensitive sides of the gas sensors or another Analyzer is supplied.

An example of such a drying device is located in [9]. However, this requires a significant Auxiliary energy for electric heating, what an autonomous Respiratory equipment is not practical. That of drying devices of this kind suggested prelude of a chemical drying agent in front of the gas-sensitive sides The gas sensors would also have the disadvantage that the Desiccant to a sufficient for the measurement Flow should be monitored, and that without further energy-consuming means - such as pumps - and hardly It would be possible, the analyzed respiratory gas the cycle again supply or expel it from the respirator, wherein the latter would also be a detrimental waste of breathing gas.

In summary, it can be stated that the previous State of the art for respiratory equipment, especially for autonomous Respiratory equipment, not an absolutely perfect solution for the Condensation problem on the electrical and electronic Components of the gas sensors or the other electrical Components of the metering device knows. The known solutions are either expensive to implement, do not work under all operating conditions, the proof of function in Product liability processes are difficult or they are for autonomous breathing equipment not practical.

Presentation of the invention

Beyond this published prior art the inventor already has certain patent pending improved solutions to the described condensation problem found. In [10], a gas sensor is disclosed which is waterproof can be shed without the above Problems occur for the pressure compensation of the gas sensor. However, then have the electrical leads of the sensor usually to the terminal pins (4) of the connector (11) be soldered. This complicates the replacement of gas sensors in the field, which is undesirable especially with military equipment. In [11], there is disclosed a gas sensor device incorporating a Desiccant used to compensate for the pressure Sensors needed, taken from the breathing circuit gas so to dry far, that condensation is avoided. Here must however, the desiccant will be swapped more often, as well then it is annoying if this in a screw-in Cartridge is located. Despite the mentioned disadvantages could themselves prove these solutions in practice and they solve that Condensation problem more reliable and complete than that Above illustrated prior art.

In the course of the applicant 's inventive step on the Area of rebreathers resulted in the Task, another solution to the condensation problem to be found on the electrical components of the gas sensors, the especially suitable for use in autonomous mixed gas Rebreather is suitable, but also in others Circulatory breathing apparatus can be used, and the opposite the previously known solutions of the previous state of the Technology and the inventor's earlier solutions has to have a sure demonstrable mode of action, basically without consumables like Desiccant and without special pourable gas sensors to get along, and to be realized with little effort.

This problem is solved by a novel device for Mixed gas supply in recirculation breathing equipment, which is a new Principle of action to avoid the condensation problem to the electrical and electronic components of the gas sensors embodied by these devices.

The novel mode of action is based on the basic idea, in one Device for mixed gas supply in Kreislaufatemgeräten for Keep dry the electrical connection side of the gas sensors the mixed gas supplied from the automatic valve itself take advantage of this because of regulations be absolutely dry must be in order to avoid unwanted condensation in the Compressed gas tank and icing of the pressure reducer and the to avoid automatic valve. The drying of the Mixed gas takes place according to the known prior art regularly already in the compressor, the compressed gas tank filled. In ordinary diving equipment, the used up Discharge breathing gas into the environment instead of preparing it, causes the dry breathing gas regularly dryness in the Mouth of the user. Nevertheless, nobody seems to be up yet The idea came from this intrinsically annoying property of a respiratory automatic valve derived dry respiratory gas in an advantageous manner as a novel mode of action for Keep dry the connection side of the gas sensors in one Exploit recirculation breathing apparatus.

This new mode of action can be used to keep dry electrical and electronic components of the respirator be extended.

This novel principle of action is realized by the fact that in the novel device for mixed gas supply from the automatic valve-derived absolutely dry mixed gas not as in the prior art directly in the Breathing gas flow is directed, but that it first the Connection sides of the gas sensors - possibly also other electrical and electronic components of the breathing apparatus - is fed to keep them dry, and that it only then at least a first pressure compensation means in the Breathing circuit drains off.

First pressure compensators are by the two tasks characterized, first, the excess part of the automatic valve derived dry mixed gas in the Derive breathing circuit, so that at the pressure equalization membranes the gas sensors to the breathing circuit no Overpressure arises, and secondly, moist breathing gas from the To prevent breathing circuit from being connected to the connection sides of the Gas sensors or the other dry-containing electrical and electronic components.

First pressure compensating means are placed between the outlet of the automatic valve and the breathing circuit arranged. in the The simplest case is sufficient for the realization of the first Pressure equalizing means a single directional valve. Depending on The requirements for the breathing apparatus can also dry cartridges with a drying agent or a combination of at least a directional valve and a drying cartridge first Pressure compensation means are used. The use of a Drying agent is always optional, because the Device according to the invention can also without such get along.

In this way, the device according to the invention succeeds for mixed gas supply in a surprisingly simple way, by Exploitation of the supplied from the automatic valve dry mixed gas condensation on the electrical connections and supply lines of the gas sensors or on other electrical or electronic components of the Respirator reliably prevent the interaction the automatic valve and the first pressure compensator always a perfect pressure equalization of the pressure compensation membrane the gas sensors ensured.

The invention has compared with previous solutions [10] [11] the same inventor the additional advantage, without aggravation the field interchangeability of the gas sensors on a Desirable to completely dispense drying agent, or such at least so much to spare that it is much rarer has to be exchanged than with the previous solution [11].

Compared with the known prior art, the invention has the Advantage, about a new mode of action to prevent the Condensation at the electrical connections of the gas sensors or to the other electrical or electronic Components of the breathing apparatus, its function proven at any time and also understood by lawyers can be, and that is why any suspicion as Potential cause of accident is sublime.

The invention thus defuses the product liability problem significantly paves the way for a triumphal march of it equipped electronically controlled mixed gas recirculation dipping devices on the world market.

Enumeration of the drawings

FIG. 1 shows the simplified basic structure of a Mixed gas - Kreislaufatemgerätes according to the prior art Technology.

FIG. 2 shows a commercially available gas sensor according to FIG known prior art, to explain its internal Components partly cut open.

Figure 3 shows schematically the novel device for Mixed gas supply according to the main claim.

Figure 4 shows schematically a further developed novel Apparatus for mixing gas supply.

Figure 5 shows schematically a novel device for Mixed gas supply, in which the first pressure equalizing agent Directional valve is.

Figure 6 shows schematically a novel device for Mixed gas supply, in which the first pressure compensation means a Drying cartridge is.

Figure 7 shows schematically a novel device for Mixed gas supply, in which the first pressure compensation means a Combination of a directional valve and a drying cartridge are.

FIG. 8 shows by way of example the internal structure of a Combination with a directional valve first Pressure equalizing agent particularly suitable drying cartridge, the itself contains another directional valve.

Figure 9 shows an example of a longitudinal section through a Practical realization of the device according to the invention for Mixed gas supply in a rebreather, in which the Gas sensors in a particularly advantageous sensor unit are housed.

Figure 10 shows a cross section through the Sehsoreinheit the Figure 9, from which the position of the pressure equalization channels of Sensor unit is completely recognizable.

Description of the invention with reference to the figures

The principal functional scheme of the invention Apparatus for mixed gas supply is exemplary in FIG shown. For this purpose, from the figure 1 for the invention relevant cutout according to the known prior art copied and became the characterizing elements of the invention added. Those taken from the figure 1 unchanged Components are no longer for clarity if this is the case for the following explanation of the Invention is no longer necessary.

According to the known prior art of Kreislaufatemgeräten There is a breathing circuit in which a breathing gas flow (29,30) flows, as well as an automatic valve for Mixed gas supply (22) and at least one gas sensor (1) with dry electric or electronic Components that are connected via its rear connection opening (3) are accessible.

The automatic valve compensates for a negative pressure, it opens when the breathing apparatus has a relative negative pressure Balance is, and it closes when the Negative pressure is balanced.

The invention is characterized in that in a Kreislaufatemgerät derived from the automatic valve dry mixed gas (23) is used to dry electrical or electronic components of the gas sensors.

This can be achieved in a device for mixed gas supply be realized by the automatic valve originating dry mixed gas (23) not immediately, but via first pressure compensation means (31) into the breathing circuit passes, with part of the automatic valve originating mixed gas before first pressure equalizing agents branched off and the dry-containing electrical or electronic components of the gas sensors is supplied.

The simplest realization of the device according to the invention contains an antechamber (34) over the first Pressure equalizing means (31) with the breathing circuit (29, 30) so in Connection stands that the gas located in the antechamber through the first pressure equalizing means into the The breathing circuit can escape as soon as it enters the antechamber greater pressure prevails than in the breathing circuit. Would in the Prechamber on the other hand a smaller pressure prevail than in Breathing circuit, then opens the automatic valve and it a pressure equalization takes place by the automatic from the Valve-derived dry mixed gas (23) in the antechamber flows.

The first pressure equalizing means may be on the side of the Breathing circuit at any point connected to this become. You could, for example, also in the deformable Sack of counterlung flow. For the sake of robustness and the However, the best possible function of the mixing process are Prefer realizations, where the first Pressure equalization means the pressure equalization between the antechamber and a solid mixing chamber (17) effect.

The dry-containing electrical or electronic Components on the connection sides (3) of the gas sensors (1) stand with the antechamber (34) in connection, which am the simplest way can be realized that the Gas sensors are housed in a part of the antechamber, being screwed sealed in threaded holes, located in the wall between the mixing chamber and the antechamber are located. As a sealant is an O-ring, the usually with standard gas sensors standard on the foot the thread on its gas-sensitive front (2) already is available.

In this way, the gas-sensitive front pages (2) the gas sensors with the breathing gas flow (30) from the mixing chamber (17) directly related to what their function while their moisture sensitive ones are coming in Backs and their electrical leads in the dry prechamber (34) are located. flawless Solutions for watertight implementation of electrical Connecting cables through housing walls to the evaluation electronics have long been known in the art. The Evaluation electronics and the other electrical components However, the metering device can also be kept dry Pre-chamber will be accommodated if this is big enough is performed.

First pressure compensation means can be realized as a Directional valve, a drying cartridge, or a combination of Directional valves and a drying cartridge. Furthermore any conceivable means is the first one Pressure compensation means, as long as the tasks of the first Pressure equalizing means, already shown above, can fulfill.

Depending on the realization of the first pressure compensation means and the responsiveness of the automatic valve can not always be completely ruled out that in case of incidents, resolved by extreme operating conditions or in case of failure a directional valve or total exhaustion of the Mischgasvorrates, not a wet breathing gas from the Mixing chamber could get back into the antechamber. This penetrating moist breathing gas could then to the connection sides get the gas sensors, condense there, and damage Serve.

Figure 4 shows schematically a further developed novel Apparatus for mixed gas supply, with said Accidents better cope, and in addition to a particularly advantageous realization of an optimal Temperature compensation of the gas sensors can achieve.

In the further developed device that gets out of the automatic valve (22) derived dry mixed gas (23) first in an antechamber (34). That in the antechamber Gas as described above via first Pressure equalizing means (31) in the breathing circuit (29, 30) arrive, however, only via second pressure compensation means (36) to the electrical and electronic dry-containing Components on the connection sides (3) of the gas sensors (1). These parts of the gas sensors are in their own Sensor chamber (35). The sensor chamber can be used for all gas sensors to be together. But it can also be any gas sensor in one be housed own sensor chamber. The second Pressure equalizing means (36) connect the interior of the prechamber with the interior of the sensor chamber (s) and they allow one bidirectional pressure equalization of the sensor chamber (s) with the Antechamber, this pressure compensation process is in the figure with the Gasflußpfeilen by the second pressure equalizing agent clarified.

Second pressure compensation means have the purpose of Connection sides of the gas sensors a more extensive protection against moisture or condensation in the case provide that an accident occurs in the device, the in particular the desired action of the first pressure compensation means diminished or abolished, so that contrary to the intentions of Invention yet humid breathing gas or even condensation from the breathing circuit back into the antechamber.

Any second pressure equalizing means useful for this purpose may be used. Possible realizations second Pressure compensation means are pressure equalization channels of small size Cross-section showing the gas exchange between the antechamber and the sensor chamber to the necessary pressure equalization measure restrict, or dry cartridges, a desiccant contain, or a combination of the said means. The Use of directional valves would be here as well conceivable, but seems to be rather an unnecessary complication.

If it is possible by a particular embodiment of the sensor chambers, to achieve a particularly small gas volume of the sensor chambers in a particularly good heat exchange with the breathing gas in the mixing chamber, then as two tes pressure compensation means simple pressure equalization channels of small cross-section may well be sufficient in case of malfunction of Nevertheless, the first pressure compensation means to ensure a safe termination of the insert.
Such an implementation of the invention, which does not require a desiccant, will be described later.

First, with reference to the figures 5 to 8 possible Realizations of first pressure compensating means in connection with the device according to the invention in the manner of Figure 3 exemplified. It is understood that the hereby shown in the first pressure compensation means also in the further developed device used in the manner of Figure 4 can be.

In the figure 5 is the simplest possible example Realization of the first pressure compensation means (31) as Directional valve (32) illustrated. This directional valve allows it in the prechamber (34) located gas in the Mixing chamber (17) and thus to escape into the breathing circuit, if in the antechamber towards the breathing circuit relative overpressure prevails. A relative negative pressure in the Antechamber equalizes the automatic valve (22), as already was detailed above. An almost perfect Pressure equalization located in the gas sensors Pressure compensation diaphragm is given by both commercial directional valves as well as commercially available automatic valves already at a few tens of millibar Can address pressure difference. Suitable as a directional valve so-called mushroom valves made of an elastomeric material, or any other suitable valve for this purpose.

In this variant, the pressure balance works only then if that is fed to the automatic valve Mixed gas supply is not completely exhausted when using the device becomes.

FIG. 6 shows by way of example a realization of the first embodiment Pressure compensation means (31), which also in the case of Exhaustion of the mixed gas supply pressure equalization of Prechamber and thus the gas sensors is always guaranteed, by the first pressure equalizing means (31) as a drying cartridge (33) is realized, in which there is a desiccant, that in the figure as small balls within the part cut dry cartridge is shown. Before the Exhaustion of the mixed gas supply is the drying cartridge at Pressure compensation processes mostly from dry, from the automatic valve (22) derived mixed gas (23) in the direction flows through the mixing chamber (17), and the drying agent is spared. Some types of drying agent (for example, based on bentonite) are by them flowing dry mixed gas even regenerated something. Just when the mixed gas supply supplied to (21) is exhausted, or the automatic valve responds delayed, and the Ambient pressure rises, then a small amount of breathing gas can out the breathing circuit from the mixing chamber (17) through the Through the dry cartridge back into the antechamber, what in the figure by the from the mixing chamber (17) in the Prechamber (34) pointing gas flow arrow is symbolized. This in the drying cartridge located desiccant extracts it Breathing gas flowing through the moisture largely, so that according to the task of the first pressure compensation means no moist breathing gas from the breathing circuit back into the antechamber but only a largely dried breathing gas, causing the risk of condensation on the electrical Connection sides of the gas sensors is also banned. Out For reasons of breathing resistance, the drying cartridge must be in this Case, however, have a relatively large cross-section. at Diving equipment is not such a realization practicable because at great depths the breathing gas is a much larger Density than under atmospheric conditions. at Respiratory equipment for atmospheric conditions has the realization according to Figure 6 but the advantage, without directional valves get along, which are known to be prone to failure than Dry cartridges. Such is for the latter application about as big as an ordinary gas mask filter.

Figure 7 shows schematically and by way of example also for Diving apparatus suitable modification of the device of Figure 6. Here are first pressure compensation means (31) realized by a combination of directional valves (32) and a Drying cartridge (33) containing a desiccant. at an overpressure in the antechamber (34) can be in it located gas via the directional valve (32) in the Mixing chamber (17) and thus enter the breathing circuit. This gas flow, symbolized by the lower arrow of (34) According to (17), it is subject to only low resistance the directional valve. At a negative pressure in the antechamber can Breathing gas from the breathing circuit from the mixing chamber over the Dry cartridge with the desiccant in the Get to the antechamber. This gas flow is symbolized by the upper arrow, from (17) to (34). Negative pressure in the antechamber can with proper function of the automatic valve on not occur. However, this speaks too insensitive or delayed, or is the one supplied to (21) Mixture of gas completely exhausted, then provides the drying cartridge that, nevertheless, a pressure equalization takes place, and that the Gas sensors are not caused by too much negative pressure in the Damaged antechamber.

Figure 8 shows an example of the cross section through a Drying cartridge (33), which has its own directional valve (32) contains. Such a drying cartridge, in which the Desiccant is a directional valve upstream, is for a device according to Figure 7 particularly suitable, since the Desiccant is spared best possible. A convenient one Construction of such a drying cartridge, from left to right, consists of a spring washer (57) having a valve cap (58) in the drying cartridge locked and against resilient curved Screen discs (59) presses on the desiccant (60) to hold his place. To get out of the drying agent To keep originating dust from the directional valve is a gas-permeable filter material (61) provided, for example Cotton wool. Such a drying cartridge can with its thread, on right end recognizable, in a device in type of figure 7 in the partition between the mixing chamber (17) and the Prechamber (34) releasably and sealed attached. When Sealant is an O-ring.

As a drying agent in this and the other Dry cartridges are commercially available drying agents, the gas that flows through them contains water vapor remove moisture and bind it, For example, a silica gel in spherical shape.

Figure 9 shows an example of a longitudinal section through a Practical realization of the further developed device for Mixed gas supply in an electronically controlled self-mixing rebreather whose sensor unit is in executed particularly advantageous manner, whereby at expedient arrangement of the sensor unit within the Respirator and when choosing a material with good Thermal conductivity is the best possible function of Temperature compensation of the gas sensors are ensured can. This succeeds especially when the sensor unit from Breathing gas flow is washed around.

Starting at the right side in the middle of the figure arrives the exhaled breathing gas (28) from the exhalation tube (15), the connected to a nozzle of a central section (37), first in a circulating distribution chamber (38) and then About at the radius distributed bean in the absorber chamber (39). The Atemkalkpatrone (16) from the respiratory gas flow lapped and thus against the wall of the absorber chamber thermally insulated. Collecting at the bottom of the absorber chamber Condensation or by short-term loss of the mouthpiece Penetrated seawater can through a drain valve (51) off be expressed by the breathing apparatus by using a manual control knob (41) on the automatic valve (22) an overpressure is produced in the breathing apparatus. To headstand the diver's entry of condensation into the soda lime To prevent, are the supply holes of Atemkalkpatrone (16) with a water-repellent, but gas-permeable Covered membrane (40). The construction of soda lime cartridges is not the object of this invention, but it should be noted that instead of the here shown symbolically and simplified axially flowed Atemkalkpatrone also a radial perfused soda lime cartridge can be used. In a such would be the feed holes then on the circumference and at the center of the cartridge would be one dürchlochtes central tube are located. This from the soda lime cartridge originates largely carbon dioxide-free breathing gas (29) passes into a central chamber (42) of the middle section (37) and of out there over holes that go below the gas sensors (1) are placed in the mixing chamber (17). Up to this point the presented breathing apparatus corresponds to the state of the art.

In the mixing chamber is a particularly advantageous Sensor unit (43), characterized in that the Gas sensors are mounted in a base body (44), wherein their gas-sensitive front sides (2) into a central bore (45) of the base body, and wherein the gas sensors (1) each in individual sensor chambers (35) sitting through the detachable connection of sensordomes (46) to the main body (44) are formed. This detachable connection can be a Be screwed. The gap between sensor dome and Body is sealed, for example with an O-ring. This produced a pressure equalization in the sensor chambers can be located in the body Pressure equalization channels (47), in the figure 8 due to the location the section only partially visible, with which the Sensor chambers are connected and by di e also the electrical leads of the gas sensors (25) are guided can. These pressure equalization channels in the main body of Sensor unit, described in more detail later in Figure 9 are about Supply pipes (48) connected to the pre-chamber (34). Then the pressure compensation channels and the supply pipes act as second pressure compensation means according to the characteristics of Invention, because they provide the pressure balance between the Prechamber and the sensor chamber ago.

The antechamber is formed by a suitable sealed intermediate bottom (56) in the housing tube (54) of the Respirator is used. This intermediate floor separates the Prechamber (34) from the mixing chamber (17). Should the Supply pipes (48) may not be stable enough to hold the Intermediate floor via the sensor unit with the middle section too can connect between the intermediate floor and the Middle section additional stable studs are provided. In general, however, such a measure is not necessary because the base body (44) and the sensor dome (46) of the sensor unit (43) and the supply pipes (48) preferably made of metal manufactured and therefore stable enough.

Metal conducts heat well, and the arrangement described provides by flushing the sensor unit with the respiratory gas flow safely, that the metal of the sensor unit and thus the gas in the Sensor chambers at substantially the same temperature as that Respiratory gas adopts. In addition, the middle section preferably turns off made of a stable plastic, then no Cold bridge between the environment and the sensor unit.

These measures taken together are beneficial to the best possible function of the temperature compensation electronics in the gas sensors, although this in contrast to the previous state the technology is not flushed directly by the respiratory gas flow, but according to the invention each in a dry Mixed gas filled sensor chamber are located.

Another variant for the realization of the second Compression means would be that one of the Main body originating supply pipes in a drying cartridge opens that between the sensor chamber and the Prechamber during pressure equalization flowing gas in addition Dries while the other supply pipes, which then only to Guide the electrical leads used to the sensors be sealed with a sealant so that they themselves no longer act as second pressure equalizing agent. This variant is to be preferred if the first Pressure balance means a drying cartridge or a combination used from a drying cartridge and from directional valves is, because if a desiccant is already present and Maintenance costs brings, then is a second drying agent to further increase the moisture protection no substantial overhead.

In the embodiment of the invention shown in Figure 9 is the first pressure equalizing means (31) but only as a Directional valve (32) realized. This allows the illustrated Diving equipment in an advantageous way, completely without one However, to get along drying agent, but requires a certain Care of the user supplied to (21) Never exhaust mixed gas supply. For a diving device should to be self-evident, since a completely exhausted Mixed gas supply would force to emergency rescue. During the emergency climb can but opposite in the antechamber only a relative overpressure is created in the breathing circuit, then via the directional valve in the breathing circuit escapes.

The characteristics of the invention are thereby realized by the mixed gas (23) coming from the automatic valve (22) first enters the pre-chamber (34), which then happens if in the breathing apparatus relative to the environment a relative Negative pressure prevails, which opens the automatic valve. Out the antechamber reaches the incoming dry mixed gas (34) to the connection sides of the gas sensors and thus on their Pressure equalization membranes. This is done according to claim 5 via second pressure equalizing means (36, 47, 48), wherein the Gas sensors are housed in individual sensor chambers (35). These sensor chambers are within one particular advantageous sensor unit (43) according to claim 11 characterized formed sensor dome (46) in a base body (44) of the Detachable sensor unit, which is a central bore (45), which flows through the respiratory gas to be analyzed becomes. From the antechamber this is the automatic valve derived mixed gas (23) via the first pressure equalizing agent (31), which is designed here as a directional valve (32), in the Mixing chamber (17) and thus supplied to the breathing circuit. The dry held pre-chamber contains in this practical Embodiment also the evaluation electronics (26) and the Dosing valve (19) for the oxygen. This allows the waiver on waterproof cable glands.

The remaining components in FIG. 9 follow again largely the previously known prior art. The Dosing valve (19) passes the oxygen originating from it the mixing chamber (17), where it is located with the there Breathing gas mixes. The thus regenerated breathing gas (30) passes through the sensor unit through at the gas-sensitive sides of Gas sensors (2) over a pipe bend (49) and a Feedthrough tube (50) into the inhalation tube (13). The Passage tube pierces the used Exhaled gas leading circulating distribution chamber (38) and is sealed against this. As with [1] the body of the Respiratory equipment consists of housing tubes (54) which are detachable, but sealed to the center section (37), wherein the ends of the device are closed with lids (55). The Device is by means of a running along the central axis Tie rod (52) held together at the top by means of a thread is screwed into the upper lid, and the at the lower end with a handwheel (53) is connected.

Figure 10 shows a cross section through the particular advantageous sensor unit of Figure 9 in height of the central axis the gas sensors (1). In the main body (44) of the sensor unit There is a central bore (54) through which the regenerated breathing gas flows and thus to the gas-sensitive Front sides (2) of the gas sensors arrives. The gas sensors are connected to the body releasably and sealed. On the Gas sensors are sensor dome (46) also with the main body detachably and sealed connected to one for each gas sensor own sensor chamber (35) to form.

For the releasable connections are threaded and for the Sealing O-rings.

In the main body pressure equalization channels (47) are present. These can be designed so that they are already within the Sensor unit the interior of the sensor chambers with each other connect. Such pressure equalization channels can than as from Sensor chambers leading holes of small cross-section, which in lead larger vertical holes in the body, executed become.

About the larger vertical holes can the sensor chambers supplied to the pressure equalization of the gas sensors required gas become. Due to the pressure equalization channels can also electrical connection lines of the gas sensors are performed.

It is understood from the above description that the Inventive device for mixed gas supply in Circulatory breathing apparatus largely independent of the nature of the Respirator is very versatile and convertible. she can depend on the field of application and the specific Requirements of the respective breathing apparatus by a choice of more or less complex pressure compensation means in be optimally designed, resulting in a variety possible variants results in the context of the description not all can be listed, so the description in no way as an exhaustive treatise of all possible Variants is to be considered. The possible variants and conversions The invention is based solely on the claims of Invention. In particular, the valves, including the automatic valve, in any convenient way will be realized. For example, the automatic valve instead of a membrane also via a pressure sensor be electronically controlled. The directional valves can be spring-loaded discs made of a suitable material. First pressure compensation means can be on their the mixing chamber facing side a water-repellent, but gas-permeable Diaphragm of sufficient cross-section upstream to sloshing condensation that is in the breathing circuit can be located from the first pressure compensation means keep.

The new device for mixed gas supply in Circulatory breathing apparatus achieved by inventive use the supplied dry mixed gas for keeping dry the electrical and electronic components of the gas sensors an improved over the prior art Drying effect and she is amazingly simple Working principle also understandable for lawyers and therefore about beyond doubt.

Compared to the earlier patent pending solutions the same inventor achieved the new device at least as good a drying effect, without a Desiccant should be used, and avoids Vergussmaßnahmen [10] at the gas sensors, which the Interchangeability of gas sensors under field conditions would make it more difficult.

Although the new device can optionally use dry cartridges use a desiccant, but then achieved against the previous solution [11] a much longer service life of Desiccant. Be the first pressure equalizing agent Directional valves are used together with a drying cartridge, so that the desiccant only in case of failure of the Pressure equalization of the pre-chamber via the automatic valve is flowed through, the desiccant is only in such Accidents consumed, and usually does not need more often be replaced as the gas sensors themselves, what about once Can be done during a routine maintenance in the year.

Will also be the further developed device with another Drying cartridge used as second pressure compensator, then this variant of the device achieves the best possible Functional potential under all conditions, however, bought with appropriate effort.

The description also discloses a rebreather the inventive device for mixed gas supply in one Variant is used, which do without desiccant examined. This is based on the consideration that a failure of the Mixed gas supply the diver in any case to an immediate Ascension forces, leaving a vacuum in the antechamber as well no longer arises and therefore no longer about one Desiccant must be balanced. This Rebreather uses one for temperature compensation the gas sensors particularly advantageous Sensor unit in a total construction, in the dry cartridges if necessary, as first and second pressure compensation means could be retrofitted, which is another Advantage of this design is.

Table of reference numerals

1

Gas sensor (mostly oxygen sensor)

2

gas-sensitive front of the gas sensor

3

Rear connection opening of the gas sensor

4

electrical connections of the gas sensor

5

circuit board

6

electrolyte chamber

7

Pressure compensation diaphragm

8th

Seal of pressure compensation diaphragm

9

pressed-in metal ring

10

Pressure compensation chamber of the gas sensor

11

Connectors

12

counterlungs

13

inhalation hose

14

Mouthpiece unit

15

exhalation

16

Atemkalkpatrone

17

mixing chamber

18

Medium pressure - oxygen

19

Dosing valve for oxygen

20

oxygen originating from the metering valve

21

Medium pressure - mixed gas

22

automatic valve for mixed gas

23

from the automatic valve derived mixed gas

24

Diaphragm of the automatic valve

25

electrical lines of the oxygen sensors

26

evaluation electronics

27

electrical control line of the metering valve

28

exhaled breathing gas

29

from the Atemkalkpatrone derived breathing gas (largely carbon dioxide-free)

30

regenerated respiratory gas

31

first pressure equalizing agent (between prechamber and Mixing chamber)

32

directional valve

33

drying cartridge

34

antechamber

35

sensor chamber

36

second pressure equalizing means (between prechamber and Sensor chamber)

37

midsection

38

circumferential distribution chamber

39

absorber chamber

40

water-repellent, gas-permeable membrane

41

Operating button for automatic valve

42

central chamber

43

sensor unit

44

Basic body of the sensor unit

45

Central bore of the main body

46

sensor dome

47

Pressure compensation channels (in the main body of the sensor unit)

48

supply pipe

49

elbow

50

Bushing (piercing 38)

51

drain valve

52

pull bar

53

handwheel

54

housing tube

55

cover

56

false floor

57

spring washer

58

valve capsule

59

screen disc

60

desiccant

61

gas-permeable filter material

literature

[1] Kanwisher / Starck, "Apparatus for controlling environmental conditions, suitable for use underwater ", US 3 556 098

[2] F. Parker et al, "Carbon dioxide scrubber and breathing diaphragm assembly for diving apparatus ", US 3,710,553

[3] Wible, "Closed circuit diving system with interchangeable gas conditioning packs for personal use ", WO 99/07442 A2

[4] M. Parker et al., "Self-contained breathing apparatus", WO 99/13944 A1

[5] www.cdnn.info/industry/i030304b/i030304b.html

[6] Untitled, "Diving apparatus with circulation", DE 2 104 153

[7] Zeitschrift "Tauchen", No. 10, October 2002, p. 95, Year - publishing house Hamburg

[8] A. Naim et al, "An improved temperature compensated electrochemical gas sensor and method for closely tracking the temperature variations of a gas to be sensed ", EP 0 819 936

[9] W. Vogeser et al., "Fluid Drying Apparatus", DE 37 90 537 C2

[10] Engl, "Castable Gas Sensor and Potting for this ", DPA 10328356.0

[11] Engl, "Gas Sensor Device for Breathing Apparatuses", DPA10259988.2

Claims (11)

Device for mixed gas supply in Kreislaufatemgeräten consisting of a breathing circuit in which a respiratory gas flow (29, 30) flows, an automatic valve (22) for supplying mixed gas from a pressurized gas reservoir (21), at least one gas sensor (1) with electrical or electronic components (4, 5, 11), wherein that the automatic valve opens when a negative pressure has to be compensated in the breathing apparatus, that the automatic valve closes again when the negative pressure is balanced, characterized, in that the dry mixed gas (23) originating from the automatic valve is used to keep dry electrical or electronic components (4, 5, 11) of the gas sensors (1). Device according to claim 1,
characterized, that the dry mixed gas (23) originating from the automatic valve (22) does not reach the breathing circuit directly but via first pressure compensation means (31), that part of the originating from the automatic valve mixed gas is branched off before the first pressure compensating means and the trockenzuhaltenden electrical or electronic components (4, 5, 11) of the gas sensors (1) is supplied. Device according to claim 2,
characterized, that the dry mixed gas (23) originating from the automatic valve (22) enters an antechamber (34), that the antechamber is largely sealed off from the breathing circuit (29, 30), trockenzuhaltenden that the electrical or electronic components (4, 5, 11) are of the gas sensors (1) with the pre-chamber in communication, that the pre-chamber via first pressure equalizing means (31) is connected to the breathing circuit with the proviso that the first pressure equalizing means derive a relative overpressure in the antechamber with respect to the breathing circuit into the breathing circuit, that the first pressure compensation means in the event of a relative negative pressure in the antechamber with respect to the breathing circuit can not get a moist breathing gas from the breathing circuit back into the antechamber. Device according to claim 3,
characterized, in that the dry-to-be-held electrical or electronic components (4, 5, 11) of the gas sensors (1) are located in a sensor chamber (35), is substantially sealed in that the sensor chamber from the breathing circuit (29, 30) and compared with the pre-chamber (34), in that the sensor chamber is connected to the pre-chamber via second pressure compensation means (36), whereby the dry-to-be-held electrical or electronic components of the gas sensors communicate with the prechamber, that the second pressure equalization means effect a pressure equalization between the sensor chamber and the pre-chamber. Device according to claim 4,
characterized in that a pressure equalization channel (47, 48) is used as a second pressure equalization means (36), which limits the gas exchange between the pre-chamber (34) and the sensor chamber (35) to the extent necessary for pressure equalization. Device according to claim 4,
characterized in that a drying cartridge filled with a desiccant is used as a second pressure equalizing means (36). Device according to one of claims 3 to 6,
characterized in that as a first pressure compensating means (31) a directional valve (32) is used which allows gas to flow from the prechamber (34) into the breathing circuit (29, 30) by opening and which supplies gas flow from the breathing circuit the prechamber prevents it from closing. Device according to one of claims 3 to 6,
characterized in that a drying cartridge (33) filled with a desiccant is used as a first pressure equalizing means (31), permitting gas flow through the desiccant in both directions, thereby passing from the breathing circuit (29, 30) into the prechamber (34 ) draining enough humid breathing gas, so that no humid breathing gas enters the antechamber from the breathing circuit, but only a largely dried breathing gas. Device according to one of claims 3 to 6,
characterized in that a drying cartridge (33) filled with a desiccant (60) is used as a first pressure compensation means (31), which contains a directional valve (32) which through the desiccant only one from the breathing circuit (29, 30) into the prechamber (34) allows leading gas flow, wherein the desiccant deprives the moist humid breathing gas enough moisture, so that from the breathing circuit no humid breathing gas enters the antechamber, but only a largely dried breathing gas. Device according to one of the above claims,
characterized in that it comprises a sensor unit in which at least one sensor chamber is formed, wherein the sensor unit is made of a thermally conductive material, and the breathing gas flow of the breathing circuit is so washed that there is a good heat exchange between the interior of a sensor chamber and the respiratory gas flow , Device according to claim 10,
characterized, that the basic body (44) of the sensor unit, having a central bore (54) that the gas sensors (1) are releasably connected to the base body so that the gas-sensitive front side (2) have the gas sensors in the central bore, in that sensor chambers (34) are formed by detachably connecting sensor cathodes (46) to the base body via the gas sensors, in that pressure compensation passages (47) are present in the main body, that this pressure equalization channels are part of the second pressure compensating means of the device.

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