DE102016009486A1 - Blower filter system and header monitor unit in such a blower filter system - Google Patents

Abstract

The invention is a blower filter system and a headpiece monitor unit (26) in such a blower filter system, wherein the blower filter system comprises a header (10) and a blower filter device feeding the header (10) via a hose (16) having a differential pressure sensor associated with the header (10) (22) for determining measured values for a differential pressure between an interior of the head piece (10) and the surroundings and an indicating element (24) in the head piece (10) which can be activated at a negative pressure in the interior of the head piece (10).

Description

The invention relates to a blower filter system with a blower filter device with a helmet or a hood in particular after DIN EN 12941 or with a blower filter device with a full mask, half mask or valve mask in particular after DIN EN 12942 , Helmet, hood, full face mask, half mask, valve mask and the like are collectively referred to as the head of such a blower filter system. Furthermore, the invention also relates to a monitor unit in a head piece (head piece monitor unit) of such a blower filter system.

Blower filter systems of the type mentioned above are used for light and medium respiratory protection and support the user of respiratory filters by reducing the breathing resistance in contrast to conventional gas masks and thus make a long and fatigue-free application possible. A fan filter system comprises as the main components on the one hand the most worn on the belt fan filter device and on the other hand, for example, designed as a hood or mask and sometimes acting as head protection cover head piece. These two components are usually connected to each other via a hose. Contaminated ambient air is sucked by means of the blower filter device through a filter and thereby freed of harmful substances and then passed through the hose to the head and so supplied to the respirator.

In addition to the main function of air transport, the blower filter unit informs the respiratory protector by means of visual or acoustic signals in addition to the current operating status and any errors. For the respirator the safe function of the blower filter system is of vital importance. Therefore, the information about a malfunction of the blower filter device must reach the respirator safely. However, it has been found that, depending on the conditions of use, the respirator is often hardly able to perceive visual signals of the fan filter system in the case of carrying on the back or even acoustic signals in situations with high noise exposure, due to the respective environmental situation.

Consequently, there is the necessity of informing the respiratory protection carrier, which is sometimes referred to below as the user for a short time, about the function of the fan filter system, in particular of the fan filter device included therein.

For this purpose, a suitable alerting and information system is provided, which is connected to a blower filter device by cable or wirelessly. With this, status information of the blower filter device and possible alarms can also be displayed in the header. This ensures that the respirator is informed about the vital condition of the blower filter device.

From the DE 101 47 045 A For example, a data communication system for a headgear mask or helmet is known. The local headgear covering has a data display in which measured data of individual measuring devices are displayed on the data display as a function of commands transmitted by voice input to the wearer of the respective head protection cover.

The DE 20 2010 012 023 U On the other hand, it does not aim to provide information to a specific task force, but rather to inform operational line personnel. There, an occupational health and safety system is described, in which a body function sensor arrangement detects at least one monitoring variable related to a body function of a respective emergency force and transmits it to a remote control device so that emergency line personnel can monitor the emergency force. The body function sensor arrangement should be able to detect different body functions with a plurality of body function sensors. Mentioned in this respect are a pulse detection, a body temperature detection, a respiration detection, a blood oxygen detection, a blood pressure detection and an arrangement for detecting a heart activity of the emergency personnel. Also addressed is an embodiment in which the occupational safety system comprises a respiratory gas arrangement which supplies the deployment force with inhaled gas and discharges exhaled gas and detects information about the respiration of the deployment force with a respiration detection arrangement. With regard to the information recorded there, the respiratory rate, a tidal volume, a breathing gas consumption per unit time and an exhaled gas composition are mentioned.

In the US 2005/022817 A an approach is described in which in a respirator switching between a filter operation in which the ambient air filtered is provided as breathing air available and no air is taken from entrained compressed air cylinders, and a compressed air operation in which the breathing air is removed from the entrained compressed air cylinders , should be possible. In this way, the possible duration of use for, for example, firefighting personnel should be increased, because not during the entire operating time breathing air is removed from the entrained compressed air cylinders.

The invention is thus based on the problem, the respirator even better and to be informed immediately about any faults of the blower filter system.

The invention solves this problem with a blower filter system having the features of claim 1.

For this purpose, in a blower filter system of the type mentioned above, which comprises a headpiece for supplying a respirator with breathing air and a headpiece via a hose-feeding blower filter device, in addition a head piece associated differential pressure sensor for determining measured values for a differential pressure between an interior of the head piece ( Breathing space) and the environment, an activatable at a negative pressure in the interior of the head piece display element in the head, and a unit with a logic and decision logic and means for respiratory phase detection and means for Atemfrequenzbereichsüberwachung provided in a signal path from the differential pressure sensor to the display element.

The unit with the linking and decision logic ensures, by means of the means for respiratory phase detection and respiratory frequency range monitoring, that only interference-free pressure signals reach the evaluation and disturbed signals are discarded.

The respiratory frequency range monitoring means or means will also be referred to below as respiratory frequency range monitoring and the function performed will also be referred to as respiratory frequency range monitoring. The respiratory frequency range monitoring performs a check of the signals of the differential pressure sensor to a physiologically meaningful frequency range. This frequency range is sufficient at rest from about 12 1 / min up to 32 1 / min at high physical stress. If this area is left, it can be assumed that the pressure signal is disturbed and the signal is classified as disturbed. In addition, the respiratory rate does not change abruptly or suddenly. When changing the respiratory rate by more than 25% between two respiratory phases, it is also to be assumed that there is interference with an interfering signal.

The means for respiratory phase detection is or will hereinafter also be referred to as the respiratory phase detector and the executed function as respiratory phase detection, and the respiratory phase detector, for example, only evaluates those signals which have been assessed by the respiratory frequency range monitoring to be physiologically sensible. As a result, the respiratory phase detector is able to robustly detect the respiratory phases of the respirator from the measured values from the differential pressure sensor, i. H. To distinguish phases of inhalation (inspiration) from phases of expiration (expiration). In the same way, a reverse sequence is conceivable, such that inhalation pauses of a user of the blower filter system, ie times of maximum inhalation, are detected by the respiratory phase detector based on the measured values from the differential pressure sensor and then a plausibility of a recognized inhalation pause is determined on the basis of anatomically possible occurrence probabilities by means of the respiratory frequency range monitoring. On this basis - but without waiving any further generality - the following description will be continued. Both sequences outlined above are always to be read and regarded as included in the description presented.

The linking and decision logic evaluates the results of the respiratory phase detection and respiratory rate range monitoring such that only interference-free portions of the pressure signal for further evaluation and processing are used and thus upon repeated achievement of a negative pressure signaling by means of the display element is effected, then the respiratory protective or warns a person commissioned to monitor the underpressure situation against an insecure respiratory protection state.

The mere consideration of the pressure conditions inside a protective helmet is known per se. For example, that describes US 5,035,239 monitoring the pressure within a face mask by means of a differential pressure sensor. When the mask internal pressure drops below a predetermined threshold value, a display element is actuated, which then outputs a warning tone. This omits the problem outlined above in the evaluation of the differential pressure measurement values and reliable detection of a negative pressure situation is currently not guaranteed.

From the US 2010 / 083967A1 An approach is known in which an overpressure in a face mask is to be ensured as a function of the respiratory activity of the respirator. For this purpose, the position of an exhalation valve is monitored and, if necessary, a warning lamp is activated. The advantage of the present invention over this prior art is that the monitoring can be performed independently of a detection of valve positions, for example, a valve position of an exhalation valve, and accordingly a corresponding sensor and signal lines are not required.

Approaches for the computational determination of a beginning of an inhalation and an end of an exhalation are from the WO 2013/082 649 A1 known.

Also for the detection of negative pressure situations proposed here, in particular during special respiratory phases, in particular breathing pauses, a head piece with a sealingly lying mask is advantageous. In the case of headers without gasket on the face (similar to those of welders or painters), where the incoming air supplied by the fan flows down only from above - mostly from the forehead area - often cause actual air movements disturbances of the pressure signals. Such air movements arise, for example, due to head movements, crosswinds or the like. Such disturbances can make respiratory phase detection more difficult.

The use of a differential pressure sensor assigned to the head piece takes into account the fact that it is crucial for the respiratory protection to exclude negative pressure in the headpiece during the inhalation phase. Only then can it be assumed that the inhaled air originates exclusively from the air supply through the blower filter device and has not penetrated from the possibly contaminated environment and any leaks in the head piece into the interior of the head piece.

Current blower filter systems ensure by a significant oversupply of air in the interior of the head piece that the inhaled air comes exclusively from the air supply through the blower filter device. Excess air constantly flows through the exhalation valve into the environment. In addition, the supplied air is used to purge the carbon dioxide (CO ₂ ) enriched exhaled air from the header. A special enrichment of the exhaled air with carbon dioxide, however, becomes clear only when the respirator begins to tire or hypoxia occurs.

A negative pressure situation can arise due to leaks, which in turn can result from the carrying situation of the head piece or a possible damage to the head piece.

By the head piece associated differential pressure sensor can detect negative pressure situations in the head and from this it is possible with a corresponding activation of the also provided in the head display element a related information of the respirator. The differential pressure sensor measures the differential pressure between the interior of the header and the environment and outputs a related measurement. The activation of the display element then takes place on the basis of the respective measured value or a processed form of the measured value. In any case, in a blower filter system comprising a differential pressure sensor assigned to the head piece, the respiratory protective device can be informed immediately by means of a display element actuated on the basis of the measured value supplied by the differential pressure sensor about a possible negative pressure situation in the head piece.

A special feature of the blower filter system proposed here is that an evaluation of the measured values from the differential pressure sensor with respect to a possible negative pressure situation during inspiration pauses (times of maximum inhalation) of the respirator, so the user of the blower filter system takes place. For this purpose, the fan filter system comprises a respiratory phase detector as a means for detecting respiratory phase for the detection of inhalation pauses of the respirator. Because the pressure conditions in the interior of the head piece on inhalation and exhalation of the respirator inevitably change, the pressure conditions during breathing pauses and especially during pauses in breathing are particularly characteristic of a detection of a possible negative pressure situation. Thus, due to the detection of respiratory phases and due to an evaluation of the measured values of the differential pressure sensor, the fan filter system delivers particularly reliable results when signaling a low-pressure situation and avoids false alarms and, above all, unsafe respirators.

To detect a Einatempause takes place by means of the Atemphasendetektors an analysis of the differential pressure signal. From a recognized inspiration interval, ie a recognized phase of maximum inhalation (local minimum in the differential pressure signal), a time value results with respect to the differential pressure signal. With such a time value, the differential pressure signal can be checked at a location determined by the time value with respect to the presence of a possible negative pressure situation, for example by comparing the amplitude of the differential pressure signal at the respective time value with a predetermined or predefinable threshold value and falling below the threshold value actual presence of a vacuum situation is closed. Then, a signal for driving the respective display element or a plurality of display elements is generated.

Another special feature of the blower filter system proposed here is that it comprises, in the signal path from the differential pressure sensor to the display element, a device or software functionality acting as means for respiratory frequency range monitoring or a combination of software functionality with associated device elements (μP, μC, SPS). This is the plausibility check of a recognized respite based on anatomically possible occurrence probabilities of inhalation and / or Ausatempausen certainly. The inhalation pauses result, for example, as locations of the minima between in each case two adjacent zero crossings in the differential pressure signal. For the plausibility check, it can be considered whether the determined location of the respite is sufficiently in the middle between the two zero crossings. If this is not the case, it is more likely that the differential pressure signal is piecewise faulty or that, for example, only a local extreme value has been detected. An alternative or additional possibility for the plausibility check is to consider a duration during which the differential pressure signal remains at the level of the determined extreme value, too short a duration, ie a duration below a predetermined or predefinable time limit, to a false evaluation or indicates a defectiveness of the differential pressure signal. Other statistical or other criteria are also conceivable, for example, a sufficient steepness of the course of the differential pressure signal before the extreme value determined as Einatempause, etc. By such a respiratory rate range monitoring is used, it is possible to further reduce false evaluations.

Finally, a special feature of the fan filter system is that it also includes the logic of connection and decision in the signal path from the differential pressure sensor to the or each display element. This is on the one hand for linking a recognized Einatempause of the respiratory protective device with a measured value obtained from the differential pressure sensor and on the other hand to decide with regard to the presence of a negative pressure situation in the header determined based on the measured value. The recognized breathing in of the respirator, ie a detected phase of maximum inhalation, specifies a relevant for the evaluation of the differential pressure signal time. The value of the differential pressure signal at this time is evaluated for decision as to the presence of a negative pressure situation in the header. A negative pressure situation is present when the determined associated differential pressure value is below a predetermined or predefinable threshold value. Optionally, it can be provided that it is only decided to have a negative pressure situation if the determined differential pressure value is below the predefined or predefinable threshold value at least for a predefined or predefinable period of time. With a consideration of a duration of the undershooting of the threshold value and without taking into account such a duration, this can optionally be expanded to the effect that the presence of a negative pressure situation is only decided if the threshold undershoots during a predetermined or predefinable plurality of recognized inspiration periods, for example during four hours , five or eight consecutive pauses. This is effective to further reduce any erroneous evaluations. If, by means of the logic and decision logic unit, a negative pressure situation is detected during an inhalation pause recognized as plausible, the unit with logic of logic and decision generates the alarm signal for controlling the display element.

As a display element is an optical and / or an acoustic display element into consideration. In the case of an optical display element, this can for example trigger different optical stimuli (color, brightness, blinking interval, etc.). The same applies in principle to an acoustic display element and the acoustic stimuli that can be triggered thereby (pitch, volume, tone sequence, etc.). Depending on the measured value supplied by the differential pressure sensor, a specific activation of the display element can thus also be carried out, which informs the respiratory protective device of the extent of the respectively detected negative pressure situation and, for example, in the case of only a slight negative pressure situation to trigger the display element to emit an optical signal first color and in a serious negative pressure situation leads to a control of the display element for emitting an optical signal having a second color. The specific reaction to the degree of the respective detected negative pressure can also be designed with finer granularity, so that, for example, as the severity of the detected negative pressure situation increases, a combination of different optical stimuli is displayed by the display element (for example color and brightness or color and blinking). Furthermore, the color and the flashing frequency can then change with the severity of the detected negative pressure situation, so that the respiratory protective carrier is oriented very precisely over the function and possibly a residual function of the blower filter system.

The described optical signals are only examples and also acoustic signals or a combination of optical and acoustic signals and a combination of corresponding display elements come into consideration. Additionally or alternatively, an indication of a possible negative pressure situation by means of tactile perceptible signals into consideration. The activatable display element then results, for example, in a vibration of the head piece or of a part of the head piece which is readily perceptible to the respiratory protector. Again, an adaptation of the display to a severity of the respective negative pressure situation is possible by a frequency and / or amplitude or frequency sequence of the vibration is adapted to the severity of the vacuum situation or is.

Advantageous embodiments of the invention are the subject of the dependent claims. Here used backlinks indicate the further development of the subject matter of the main claim by the features of the respective subclaim. They should not be construed as a waiver of obtaining independent, objective protection for the feature combinations of the dependent claims. Furthermore, with a view to an interpretation of the claims in a closer specification of a feature in a subordinate claim, it is to be assumed that such a restriction does not exist in the respective preceding claims.

In one embodiment of the blower filter system, the headpiece is a mask, particularly a mask which fits snugly on a face of a user / respirator, for use in environments with hazardous concentrations of gases (chemical, biochemical, biological, flue gases) or vapors ( Propellants, aerosols, solvents) and the like. Such a mask has a mostly passive exhalation valve, in particular in one embodiment as a check valve, via which the user exhales used exhaled air to the environment.

In one embodiment of the blower filter system, a low-pass filter is provided in a signal path from the differential pressure sensor to the display element. In this way, irrelevant aspects of the differential pressure signal, ie a time profile of the measured values supplied by the differential pressure sensor, can be masked out. This is particularly relevant for a possible digital processing of the differential pressure signal, because then the necessary sampling rate can be reduced and thus accompanied by a reduction of the processing power necessary for the processing of the differential pressure signal. Such irrelevant aspects of the differential pressure signal are referred to below as transient motion artifacts and result, for example, from movements or actions of the respirator and associated pressure changes.

In order to analyze the differential pressure signal for detecting inhalation pauses of the user, it is provided that a minimum between two adjacent zero crossings in the differential pressure signal, ie in a measured value curve available from the differential pressure sensor, can be determined by means of the respiratory phase detector. A respiratory phase detector can be realized in particular as part of a software functionality for processing the differential pressure signal. The device processes a digitized form of the differential pressure signal and is capable, for example, of recognizing individual zero crossings within the differential pressure signal based on a change of sign of adjacent measured values. Between two adjacent zero crossings, the minimum of the measured values enclosed between the zero crossings is then determined in a manner known per se, and as soon as the minimum measured value representing the minimum within this section of the differential pressure signal has been determined, a time value describing an inhalation interval of the respiratory medium with respect to the differential pressure signal in front.

The consideration of the minima and not also the maxima has the advantage that breathing pauses are only recognized as respiratory pauses, because at the end of the inhalation with the relatively lowest pressure in the interior of the head piece can be expected and then correspondingly low pressure situations are particularly visible.

If a signal which can be generated in the headpiece at a detected negative pressure situation for activating one or several display elements can also be transmitted to the fan filter device, the negative pressure situation can also be signaled there optically and / or acoustically, for example, so that other emergency services can assist the respiratory protective carrier can come.

If a carbon dioxide sensor is provided in the header and the blower filter system, in particular an evaluation unit in the header of the blower filter system, comprises means for activating a display element in the header in response to a reading available from the carbon dioxide sensor, the respirator can also easily detect a critical carbon dioxide concentration be brought to the knowledge.

As a place for attachment of the or each display element in the head of the fan filter system is acting as a head piece monitor unit display device into consideration. A combined attachment of a possible plurality of display elements has the advantage that they are usually perceived at a suitable mounting location of the display device of the respirator simultaneously. Such a combined attachment also has the advantage that a state of the display device is easily monitored and a separate display element for visualizing this state can be provided. In the case of purely optical display elements, a proper state of the display device would therefore be signaled to the respiratory protection wearer, for example by a green illuminated display element. At least one further display element signals a vacuum situation in the event of an error. Based the green illuminated display element recognizes the respiratory protective device thereby that a failure of an optical signal from the at least one other display element can not result from a failure of the display element or the display device and that, accordingly, the fan filter system is working properly. The display device is also suitable for displaying alarms of the blower filter device.

The above object is also achieved with a method of operating the blower filter system as described herein and in the following. In this case, measured values for a differential pressure between the interior of the head piece and the environment are determined by means of the differential pressure sensor and at a negative pressure in the interior of the head piece located in the head piece display element or one of the display elements located in the headpiece is activated to make the respirator on the low pressure situation ,

A special feature of the method is that inhalation pauses of the respirator are determined, with a check for a possible negative pressure in the headpiece during such Einatempausen. The determination of the breathing pauses allows the examination for a possible negative pressure at particularly suitable times and thus helps to avoid incorrect evaluations. A particularly efficient way to determine respiratory pauses is to determine a minimum between two adjacent zero crossings in a differential pressure signal available from the differential pressure sensor.

A further special feature of the method is that a recognized negative pressure situation or a recognized respite is checked for plausibility by means of the respiratory frequency range monitoring on the basis of anatomically possible occurrence probabilities. In this way, the risk of incorrect evaluations can be further reduced. Suitable criteria that describe a plausibility of a breathing space are particularly easy to encode in software, for example, an examination as to whether a time determined as respite is sufficiently in the middle between two adjacent zero crossings, and so on. Respiratory frequency range monitoring is implemented, for example, in the form of software with programmed step and branch sequences.

Finally, a peculiarity of the method is also that by means of the linking and decision logic, a linkage of an inhalation pause of the respiratory protection carrier recognized as plausible - a recognized phase of maximum inhalation - with a measured value obtained from the differential pressure sensor takes place. The time of inhalation gives the measured value to be considered or the value of the differential pressure signal to be considered. To decide with regard to the presence of a negative pressure situation in the head piece, this is compared with a threshold value. If the threshold value is undershot, a negative pressure situation is detected. In this case, the duration of a shortfall can be taken into account, so that the shortfall must be given at least during a predetermined period of time in order to avoid that short-term pressure changes are unnecessarily signaled as potentially dangerous negative pressure situations. In addition, a certain number of successive inspiration pauses below a threshold value can be used as a criterion for the detection of potentially dangerous negative pressure situations. This is especially the suppression of false alarms.

Embodiments of the method are characterized in that the measured values obtainable from the differential pressure sensor are digitized and a resulting differential pressure signal is filtered with a low-pass filter. Low pass filtering is effective to eliminate or at least reduce, for example, transient motion artifacts.

An embodiment of the invention will be explained in more detail with reference to the drawings. Corresponding objects or elements are provided in all figures with the same reference numerals.

The or each embodiment is not to be understood as limiting the invention. Rather, in the context of the present disclosure, modifications and modifications are possible, in particular those variants and combinations, for example, by combination or modification of individual in combination with the described in the general or specific description part and in the claims and / or the drawing features or Elements or process steps for the expert in terms of solving the problem can be removed and lead by combinable features to a new subject or to new process steps or process steps, even if they concern testing and working procedures.

Show it:

1 a respirator with a blower filter system,

2 a respirator as a possible head of a fan filter system and mounted in the headpiece display elements for information of the respirator and

3 a block diagram of a method for operating a fan filter system and for evaluating a differential pressure signal and for generating status information.

1 shows a user wearing a head protection cover in the form of a respirator. This acts as a headpiece 10 a blower filter system 12 , in addition to the head piece 10 another blower filter device 14 and a blower filter device 14 and the head piece 10 connecting hose 16 belong. On the blower filter device 14 is a filter 18 attached to the suctioned and over the hose 16 to the head piece 10 Guided breathing air filters. The blower filter device 14 is by means of a carrying strap 20 carried.

2 shows an alternative embodiment of a blower filter system 12 ( 1 ) usable head piece 10 in the form of a respirator. The blower filter device 14 ( 1 ) is not shown. Shown is still the head piece 10 leading hose 16 , As part of the head piece 10 is a differential pressure sensor 22 shown. Depending on the differential pressure sensor 22 supplied measured values is controlled by at least one display element 24 within the header 10 , allowing the user through the state of single or multiple display elements 24 (on, off, color change, flashing, etc.) about the condition of the blower filter system 12 is informed. Shown is a configuration in which multiple display elements 24 in one in the head piece 10 and there in the field of view of the user attached head piece monitor unit 26 are summarized.

The differential pressure sensor 22 measures the differential pressure between the interior of the header 10 and the environment. So can dangerous phases, in which negative pressure in the head piece 10 prevails, be recognized. The differential pressure sensor 22 is in one of the blower filter device 14 integrated alerting and information system, which is wired or wireless with the blower filter device 14 connected is. In a radio connection, the alarming and information system also includes a voltage source in the form of a battery or the like. Otherwise, the power supply via the blower filter device 14 respectively. A processing functionality in the form of or in the manner of a microprocessor or the like for processing the measured values of the differential pressure sensor 22 and for controlling one or more display elements 24 depending on the differential pressure sensor 22 The measured values obtained can be either this alarming and information system or the blower filter device 14 be assigned.

3 shows in this respect a block diagram of a method for the evaluation of the differential pressure sensor 22 obtained measured values. The method is implemented in software, for example, so that the representation in schematically simplified form also shows a corresponding evaluation algorithm. In principle, an implementation in hardware or partly in hardware and partly in software comes into consideration. For such a situation, the functional blocks shown represent corresponding hardware units.

The block diagram in 3 includes a low pass filter 30 , a bandpass filter 32 , one as a respiratory phase detector 34 functioning functional unit for respiratory phase detection (means 34 for respiratory phase detection), a functional unit for respiratory frequency range monitoring (mean 36 for respiratory frequency range monitoring; Respiratory rate range monitoring 36 ) and a logic of logic and decision 38 , The totality of in 3 shown functional units, but at least the logic and decision logic 38 together with the respiratory phase detector 34 and respiratory rate range monitoring 36 , be as a unit with logic and decision logic 38 designated. This is vorzugs- and designed, for example, as a programmable controller (processor, μC, μP, DSP, PLC) or as another programmable device with associated memory (RAM, ROM). The means 34 . 36 for respiratory phase detection and respiratory frequency range monitoring and possibly also the bandpass filter 32 are preferably in or at the unit with link and decision logic 38 arranged or as software functionalities with the unit with linking and decision logic 38 combined.

The input-side low-pass filter 30 is called differential pressure signal 40 a sequence of measured values (p (t)) of the differential pressure sensor 22 fed. One of the unit with join and decision logic 38 generated alarm signal 42 is used directly or indirectly to control one or more display elements 24 used. The alarm signal 42 can be a digital alarm signal 42 be and indicates accordingly by its level a possibly present vacuum situation. The alarm signal 42 can however also an analog alarm signal 42 be whose respective amplitude encodes a severity of any existing vacuum situation. Furthermore, the alarm signal 42 are also output in the form of a plurality of digital signals, wherein a severity of any existing vacuum situation is encoded by a number of each activated digital signals. The block diagram in 3 shows a possible signal path from the differential pressure signal 40 to the alarm signal 42 , because the alarm signal 42 based on the differential pressure signal 40 , A way to generate an alarm signal 42 based on the differential pressure signal 40 is described below.

The input-side low-pass filter 30 initially causes a filtering of the differential pressure signal 40 and eliminates disturbances and irrelevant details of the differential pressure signal for the subsequent evaluation 40 , The low pass filter 30 can be an analog low-pass filter 30 or a digital low-pass filter 30 be. For a digital low-pass filter 30 there is an input-side and not shown here, but known per se analog / digital conversion of the differential pressure signal 40 , For an analog low-pass filter 30 may in the further course of the signal processing, so for example before the respiratory phase detector 34 , Such an analog / digital conversion (also not shown) happen.

The cutoff frequency of the low pass filter 30 is above, in particular just above the usual respiratory frequencies of a user of the fan filter system 12 and at the same time also those respiratory frequencies, as they result in operational situations, ie under physical stress. Experience values are available for such respiratory frequencies, so that the adjustment of the cut-off frequency of the low-pass filter 30 is readily possible. The low-pass filtering eliminates influences on the differential pressure signal 40 not from the function of the blower filter system 12 or the breathing of the respirator. These are, for example, effects that result from a movement of the respirator and an associated movement of the head piece 10 at the head of the respirator. These effects are therefore referred to here and below as transient motion artifacts and the otherwise optional low-pass filter 30 is effective for such motion artifacts in the differential pressure signal 40 to eliminate or at least reduce.

The low-pass filtering also causes, in a manner known per se, a limitation of the output-side, filtered differential pressure signal 40 to relatively low frequencies, so that a sampling rate can be minimized. On the one hand, this reduces a memory requirement in the further processing of the differential pressure signal 40 and also the required computing power.

Because in the differential pressure signal 40 in the following with the respiratory phase detector 34 Breathing pauses are determined, namely extreme values in the differential pressure signal 40 are sought, which indicate such breathing pauses in the form of inhalation and Ausatempausen comes on the input side of the respiratory phase detector 34 a fundamentally optional bandpass filtering of the differential pressure signal 40 with the bandpass filter 32 into consideration. The bandpass filter 32 eliminated in the differential pressure signal 40 now also low frequencies that are below the usually expected respiratory rates of the respirator.

The respiratory phase detector 34 fed, filtered form of the differential pressure signal 40 is in the illustration in 3 inside the respiratory phase detector 34 symbolizing function block in idealized form shown as sinusoidal signal. The falling edges of such a signal correspond to the inhalation process of the respirator. The lower peaks of the signal correspond to a breathing space during the breathing process of the respirator. This moment represents the moment of the strongest inhalation of the respirator and is referred to in the following as maximum inhalation. A region around the lower vertex represents a phase of maximum inspiration. The rising edges correspond to an exhalation process, and the upper peaks of the signal accordingly result from an exhalation of the respirator before a subsequent inhalation process.

The respiratory phase detector 34 detects in the signal supplied to it adjacent zero crossings and then the minimum between each two adjacent zero crossings. The location of a minimum determined in this way corresponds to the time of maximum inhalation. In the illustration in 3 is inside the the respiratory phase detector 34 symbolizing functional block such a recognized minimum with an upward pointing arrow.

The or each minimum determined in this way is a candidate for times of least pressure in the header 10 , By means of respiratory frequency range monitoring 36 the time points correlated with the minima are checked for plausibility by being compared with anatomically possible occurrence probabilities. If the most plausible minimum candidates are determined, then the logic of linking and decision making is used 38 determined the differential pressure values for these times and decided whether and how long a negative pressure in the header 10 prevailed. Depending on this, the alarm signal 42 generated.

A blower filter system 12 The type described here protects the respirator against contaminated ambient air by the interior of the head piece 10 (Breathing space) kept under at least slight overpressure and at least negative pressure is avoided. In addition, however, the exhaled carbon dioxide must also be evacuated from the respiratory chamber, so that the respiratory protection does not inhale this as possible again. In such an evacuation of exhaled carbon dioxide is called a purge of the respiratory space. In general, there is no direct relationship between the pressure in the respiratory space and the freedom of the inhaled air of carbon dioxide. Rinsing is rather dependent on the flow guidance. However, there is generally a share of exhaled air in the head piece 10 , In addition to the differential pressure sensor 22 ( 2 Therefore, a carbon dioxide (CO ₂₎ sensor (not shown) may be included in the header as a further part of the alarming and information system 10 to get integrated. With the carbon dioxide sensor can continuously the carbon dioxide concentration of the head piece 10 existing breathing air checked and exceeding a limit value by activating a display element 24 ( 2 ) an alarm is generated. This requires the carbon dioxide sensor near the mouth-nose area of the headpiece 10 be placed and can detect the changes in concentration with sufficient speed. It is also possible, the concentration of noxious gases such as hydrogen sulfide (H ₂ S) or the like, despite the overpressure and the flushing of the head piece 10 get into its interior, to determine by suitable sensors and also generate an alarm when limits are exceeded.

LIST OF REFERENCE NUMBERS

10

headpiece

12

Powered Air Purifying System

14

PAPR

16

tube

18

filter

20

strap

22

Differential Pressure Sensor

24

display element

26

Headpiece monitor unit

28

30

Low Pass Filter

32

Bandpass filter

34

Means for respiratory phase detection, respiratory phase detector

36

Respiratory rate range monitor, respiratory rate range monitor

38

Linking and decision logic

40

Differential pressure signal

42

alarm

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 10147045 A [0006]
• DE 202010012023 U [0007]
• US 2005/022817 A [0008]
• US 5035239 [0016]
• US 2010/083967 A1 [0017]
• WO 2013/082649 A1 [0018]

Cited non-patent literature

• DIN EN 12941 [0001]
• DIN EN 12942 [0001]

Claims (11)

Blower filter system ( 12 ) with a head piece ( 10 ) and one the head piece ( 10 ) via a hose ( 16 ) supplying blower filter device ( 14 ), with a the head piece ( 10 ) associated differential pressure sensor ( 22 ) for determining measured values for a differential pressure between an interior of the head piece ( 10 ) and the environment and with a negative pressure in the interior of the head piece ( 10 ) due to an alarm signal ( 42 ) activatable display element ( 24 ) in the header ( 10 ), characterized by a unit with a linking and decision logic ( 38 ) as well as funds ( 34 ) for respiratory phase detection and means ( 36 ) for respiratory frequency range monitoring in a signal path from the differential pressure sensor ( 22 ) to the display element ( 24 ), by which means ( 34 ) for respiratory phase detection on the basis of the measured values from the differential pressure sensor ( 22 ) Einatempausen a user of the blower filter system ( 12 ), ie periods of maximum inhalation, are recognizable, whereby by means of 36 ) for respiratory frequency range monitoring, a plausibility of a recognized inhalation pause can be determined on the basis of anatomically possible occurrence probabilities, wherein by means of the linking and decision logic ( 38 ) a measured value of the differential pressure sensor ( 22 ), which belongs to a perceived plausible Einatempause of the user, to decide with regard to the presence of a negative pressure situation in the header ( 10 ) is evaluable and wherein in the case of a detected negative pressure situation, the alarm signal ( 42 ) can be generated. Blower filter system ( 12 ) according to claim 1, with a low-pass filter ( 30 ) in the signal path from the differential pressure sensor ( 22 ) to the display element ( 24 ). Blower filter system ( 12 ) according to claim 1 or 2, wherein the means ( 34 ) for respiratory phase detection for detecting pauses in inspiration of the user a minimum between two adjacent zero crossings in one of the differential pressure sensor ( 22 ) can be determined. Blower filter system ( 12 ) according to one of the preceding claims, wherein by means of the logic of connection and decision ( 38 ) for the detection of a vacuum situation and the generation of the alarm signal ( 42 ) a duration of a fate of the measured value belonging to a plausibly recognized inhalation interval can be evaluated below a threshold value. Blower filter system ( 12 ) according to one of the preceding claims, wherein by means of the logic of connection and decision ( 38 ) during a predetermined or predefinable plurality of recognized inspiration pauses of the user a respective measured value from the differential pressure sensor ( 22 ) for the detection of a vacuum situation and the generation of the alarm signal ( 42 ) is evaluable. Blower filter system ( 12 ) according to one of the preceding claims, wherein a for activating the display element ( 24 ) Generatable alarm signal ( 42 ) also to the blower filter device ( 14 ) is transferable. Blower filter system ( 12 ) according to one of the preceding claims, with a carbon dioxide sensor in the head piece ( 10 ) and means for activating a display element ( 24 ) in the header ( 10 ) depending on a reading available from the carbon dioxide sensor. Blower filter system ( 12 ) according to one of the preceding claims, with one or more display elements ( 24 ) and as a header monitor unit ( 26 ) functioning indicator in the header ( 10 ) of the fan filter system ( 12 ). Method for operating a fan filter system ( 12 ) according to one of the preceding claims, wherein by means of the differential pressure sensor ( 22 ) Measured values for a differential pressure between the interior of the head piece ( 10 ) and the environment are determined, wherein at a negative pressure in the interior of the head piece ( 10 ) in the head piece ( 10 ) display element ( 24 ), whereby by means of 34 ) for respiratory phase detection on the basis of the measured values from the differential pressure sensor ( 22 ) Einatempausen a user of the blower filter system ( 12 ), ie periods of maximum inhalation, are detected, whereby by means of 36 ) for respiratory frequency range monitoring, a plausibility of a recognized inhalation pause is determined on the basis of anatomically possible occurrence probabilities, whereby by means of the linking and decision logic ( 38 ) a measured value of the differential pressure sensor ( 22 ), which belongs to a perceived plausible Einatempause of the user, to decide with regard to the presence of a negative pressure situation in the header ( 10 ) and in the event of a detected low-pressure situation, the alarm signal ( 42 ) is generated. Method according to claim 9 for operating a fan filter system ( 12 ) according to claim 2, wherein the differential pressure sensor ( 22 ) and digitized with a low-pass filter ( 30 ) are filtered. The method of claim 10, wherein the inhale and exhale pauses are determined by taking a minimum between two adjacent zero crossings in one of the differential pressure sensor (10). 22 ) is determined.

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