EP1722865B1 - Blow filter device - Google Patents

Abstract

A blow filter device for breathing masks and hoods, comprising a blower which is driven by a motor and at least one filter which is arranged upstream from the blower, in addition to an electronic control system for adjusting a predefined airflow volume. The invention is characterized in that the motor is an electronically commutated direct current motor (6) which is controlled with the aid of a pulse width modulation ratio as a control variable, wherein a calibrating curve is created and stored in the memory (14) of the electronic control system and is based on a plurality of different filter resistances and a respectively corresponding pulse-width modulation ratio (PWM) and the respective motor speed (n) for a specific volume of air. The direct current motor can be controlled in the hood mode according to the speed (n) measured in relation to the respective filter resistance after activation with the aid of the associated pulse-width modulation ratio read from the calibrating curve and can be controlled in the mask mode independently of the respective filter resistance with a respective specific constant pulse-width modulation ratio (PWM) for the associated mask type, wherein the electronic control system (5) is associated with an identifying means (19,20) which is used to recognize the associated head part and to adjust the operational mode concerned.

Description

The invention relates to a blower filter device for respirator hoods and masks, which comprises a blower driven by a motor and at least one filter upstream of the blower and an electronic control unit associated with the engine for setting a predetermined air volume flow.

Respirator hoods and masks are used to provide filtered breathable air to a wearer of a hood or mask in a gaseous or particulate contaminated environment by means of a blower. The known arrangements use a fan which transports air through a filter via a hose into the hood or mask. When using these devices, during use, e.g. by filter contamination the operating conditions. This requires an adaptation of the blower speed in order to be able to keep the volume flow of the breathing air in the hood or mask constant. Various arrangements are known for the adaptation of the volume flow.

In the EP 0352938 A2 an arrangement of two pressure sensors is used, one in front of the blower and one behind the blower to measure the differential pressure to control blower speed.

The EP 0621056 A1 suggests the measurement of the back pressure behind the blower filter device, wherein the dynamic pressure generated by the flow resistance of the hood serves as a measure of the air flow.

These solutions are disadvantageous in that the use of pressure sensors is structurally complex in terms of apparatus and ultimately associated with high costs.

The DE 19502360 A1 describes a solution in which by measuring the operating current and the rotational speed of the motor, the power of the fan is regulated. A similar method is also used in the WO02 / 2329 A1 used, wherein the rotor speed is controlled by the power consumption of the motor, that is, depending on the change in resistance through the filter, the motor power must be continuously adjusted by a complex voltage and current adjustment.

Another way to control the air flow is in the WO 02 / 11815A1 described. In this arrangement, the fan speed is adjusted via the motor power of a DC motor. The motor power is adjusted so that the required flow is achieved with the heaviest filters. The adjustment requires a monthly basic calibration without a filter and manual recalibration for each filter used. With the known flow resistance of a instead of the hood to be connected to the fan filter device air flow indicator, the fan speed can be determined, which is necessary for a given volume flow. The disadvantage of this method is that under changed conditions, a recalibration is necessary. To do this, the user must disconnect the blower filter unit from the hood and connect the airflow indicator. For smooth-running filters, readjustment by hand is required. In addition, the device can not be operated with a mask.

The invention is therefore an object of the invention to provide a blower filter device for respirators and respirator hoods, which is simple and inexpensive and allows a practical use.

According to the invention, the object is achieved with a fan filter device designed according to the features of patent claim 1. Advantageous developments and refinements of the invention emerge from the subclaims.

In a blower filter device of the type mentioned above, the essence of the invention in the application of a blower associated electronically commutated DC motor, which is controlled by the control electronics with a pulse width modulation ratio as a control variable for generating a certain engine speed and a corresponding air flow rate, in the hood operating mode with a from a stored in the control electronics calibration curve, which reflects the relationship between filter resistance, engine speeds, pulse width modulation ratios and air volumes, according to the respective input resistance in a calibration mode when switching on the device based on the measured speed read pulse width modulation ratio and in mask mode with a stored in the control electronics, the respective mask type constant pulse width modulation ratio, the control electronics with the help of a he the connection point between the respirator or hood (hereinafter referred to as header) and fan filter device associated sensor detects the respectively connected head (hood or mask or mask type) and automatically sets the respective control mode.

In the calibration operation carried out in the hood operation mode after the device is switched on, the DC motor is driven with a specific value of the pulse width modulation ratio and the resulting motor speed compared with values from a calibration curve stored in a memory. From this, the value of the input resistance of the filters under the current conditions can be determined.

The blower filter device according to the invention is advantageous over the known solutions of the prior art, as it after connecting the respective head and after switching on the blower regardless of the size of the blower prevailing input resistance according to the type, number or addition of the upstream filter both in hood mode as well as in mask mode, even with different types of mask, automatically provides the required optimum air flow. If the filter resistance changes during the hood operation and falls below a limit value of the required volume flow, the blower filter device only needs to be switched off and on again, in order subsequently to supply the desired air volume again. The device is therefore easy and comfortable to use and also designed to be simple and inexpensive. As the unit operates constantly under optimal operating conditions, the life of the filters used increases.

In a further embodiment of the invention, the control electronics for monitoring the air volume flow, a display unit for signaling the exceeding or falling below the required air volume flow within predetermined limits Flow _min <Flow <Flow _max assigned and in the hood operating mode in the meantime changed filter resistance of the electronically commutated DC motor is controllable after switching off and on again and automatically reconnected with a new the corresponding filter resistance, read from the calibration curve new pulse width modulation ratio. The display unit may comprise optical and / or acoustic signal elements.

According to an advantageous embodiment of the invention, the identification means for detecting the respectively connected head part is an integrated in an air outlet port of the blower filter device and connected to the control electronics sensor communicates with differently shaped hose fittings the respiratory protection hood or respirator or different respirators and the control electronics a corresponding signal for transmits the hood or mask mode of operation or different mask modes of operation.

The sensor system may comprise a switch, which occupies a specific switching position for the hood operating mode and when connecting a respirator mask another setting for setting the mask operating mode in the control electronics when connecting the hose connection piece of a respiratory protective hood, wherein in the hose fitting of the respirator an actuating element for adjusting the switch can be arranged for the mask operating mode, and the actuator according to the respective type of mask can be designed differently and the switch for the mask operation with a stored in the control electronics, each mask type specific pulse width modulation ratio in different, each mask type specific positions can be adjustable.

In a further embodiment of the invention, the switch for signaling the respective mask type and setting the respective pulse width modulation ratio may be formed multipolar.

An embodiment of the invention will be explained in more detail with reference to the drawing, in the single figure of which is connected to a respirator hood blower filter device with an associated control electronics.

The blower filter device 1 comprises a housing 2 for various filter cartridges 3, 4, an electronic control unit 5, a motor 6 which drives a fan 7, and a connection 8 for a connecting hose 9 to a breathing hood 10. Ambient air is sucked in by the fan 7 and flows through the filter cartridges 3, 4 and via the connecting hose 9 formed with a connection part 11 into the respiratory protection hood 10 and is available to a user as purified air.

The control electronics 5 comprises an accumulator 12 for power supply, a processor 13, a memory 14, a display unit 15 with optical and acoustic signal elements 16, 17 and a switch 18 for switching on and off of the blower filter device. 1

Since a respirator or hood is operated in each case different operating mode, the control electronics 5 must recognize whether just a respirator or - as in the embodiment - a respirator 10 is connected. For this purpose, the air outlet connection 8 on the blower filter device 1 has an identification switch 19, which is electrically connected to the control electronics 5. Depending on its position (closed or open) is displayed in the control electronics 5, whether the air outlet port 8 is connected to a respirator 10 or a respirator. Whereas in the case of a respiratory mask in the corresponding connection part of the connecting hose an actuating element 20 (here shown in dashed lines) is designed to close the switch 19, such an actuating element is missing in the hose connecting piece 11 shown here for a respiratory protection hood 10, so that the switch 19 when attaching the hose connecting piece 11 remains in the open position. In the control electronics 5, a signal corresponding to the respective switch position is now generated to identify the respectively connected head part.

The motor in the fan filter unit 1 is operated as an electronically commutated DC motor 6. For driving a pulse width modulated signal is used, wherein the pulse width modulation ratio is determined by a ratio of signal on time t1 to signal off time t2. This pulse width modulation ratio (PWM) is used as the control variable and essentially determines the engine speed and thus the fan speed and the air volume flow.

In a blower filter device operated with a respirator, it should be noted that the engine speed n is inversely proportional to the amount of air delivered and depends on the input resistance of the filter cartridges 3,4. Changes the input resistance of the filter cartridges 3.4, for example, by contamination or use of different filters, the engine speed and the flow rate change in an inversely proportional ratio at the set pulse width modulation ratio. However, in order to be able to keep the volume flow constant with a change in the input resistance, the engine speed must be changed by changing the pulse width modulation ratio.

In order to supply the respiratory protection cover with a changed input resistance with a pulse width modulated motor control with different or changing input resistance still the required optimum air flow of, for example, 135 ± 7 1 / min, is stored in the memory 14 of the control electronics, a table of values or calibration curve, the relationship between pulse width modulation ratio (PWM), engine speed (n), filter resistance and airflow. To set up the calibration curve, the control variables (pulse width modulation ratios) corresponding to the different filter resistances are determined for a specific air volume flow, for example 135 l / min.

The device is put into operation with the on / off switch 18. According to the present embodiment, the control electronics 5 after connecting the hose connector 11 of a breathing hood 10 from the air outlet 8 (fan output) due to the standing in a certain switching position identification switch 19 receive a signal that a breathing hood 10 is connected. In this case, an automatic calibration process is performed. The DC motor 6 is operated at a fixed pulse width modulation ratio driven. The resulting engine speed n ₁ is measured via the Hall sensors 21 present in the DC motor 6. Thus, the filter resistance, ie the sum of the filter resistances from the filter inserts (gas filter 3, particle filter 4), can be determined on the basis of the calibration curve stored in the memory 14. With this input resistance from the stored in the memory 14 calibration curve then the value for the pulse width modulation ratio is determined at which the engine speed (working speed n ₂ ) adjusted so that the desired air flow rate (here 135 1 / min) results. With this pulse width modulation ratio of the DC motor 6 is driven.

The set engine speed n ₂ is continuously measured during operation by the Hall sensor 21 present in the DC motor 6. At the engine speed corresponding to a certain input resistance, a speed range n _min <n ₂ <n _{max is} defined in the electronic control unit 5, which defines the permissible operating range. If the input resistance of the filter cartridges 3, 4 changes, for example as a result of contamination (high resistance) or due to a leakage in the output range (low resistance), the engine speed n becomes correspondingly greater or smaller. If the measured value for the engine speed n _{2 is} outside the defined working range, an alarm is triggered by the electronic control unit 5, since the volume flow at an engine speed outside the working range no longer has the desired value. The following table shows, by way of example, the operating speeds and the associated working ranges for different pulse width modulation ratios. Pulse width modulation ratio Speed n n _min n _max 41 4300 3150 4600 55 5080 4500 5500 60 6120 5500 6700 78 7560 7150 8000

The alarm is displayed by means of the display unit 15 with optical signal elements 16 and / or acoustic signal elements 17. The alarm signals the wearer of the respirator of a change in the conditions to which the wearer must respond by either triggering another calibration procedure by turning it off and on again, adjusting a new engine speed by a new pulse width modulation ratio to restore the desired volume flow, or by he cleans the filter cartridges 3, 4 or changes.

The blower filter device 1 previously used in connection with a respiratory protection hood can also be operated with a respiratory mask. When connecting the hose connection piece of a respirator, the identification switch 19 is actuated with the actuating element 20 and thus the control electronics 5 signals that with the blower filter device 1, a respirator is to be supplied with forced air. Since the respirator, in contrast to the respirator on the user's face is tight and sealed even with a resulting in the mask negative pressure through the exhalation valve against the outside atmosphere, passes through the filter cartridges 3, 4 purified air to the user. In this case, the DC motor 6 of the blower filter device 1 with a constant pulse width modulation ratio, regardless of the input resistance of the filter cartridges 3, 4 are controlled. Thus, the masking calibration described above for hood operation is not required.

The identification switch 19 may have a plurality of switching positions in conjunction with the actuating element 20 in order to detect different types of mask, each having different inherent resistances, and to conduct a corresponding signal to the control electronics 5. Depending on the type of mask connected, a previously determined value stored in memory 14 can be set for the pulse width modulation ratio corresponding to the mask type.

Instead of the identification switch described here, sensors for identifying the various head parts for the respective operation of the control electronics can be arranged on the fan output.

LIST OF REFERENCE NUMBERS

1

PAPR

2

casing

3

Filter element / gas filter

4

Filter element / particle filter

5

control electronics

6

DC motor, electronically commutated

7

fan

8th

Air outlet connection (fan output)

9

connecting hose

10

Headboard (here respiratory protection hood)

11

Hose connector

12

accumulator

13

processor

14

Storage

15

display unit

16

optical signal elements

17

acoustic signal elements

18

Switch on / off

19

identification switch

20

Actuator for 19

21

Hall sensors

Claims (10)

1. A blow filter device for breathing masks and hoods including a blower driven by a motor and at least one filter arranged upstream from the blower, as well as an electronic control system associated with the motor for adjusting a predefined airflow volume, characterized in that

   - the motor is an electronically commutated direct current motor (6) controlled by a pulse width modulation (PWM) ratio as a control variable and equipped with speed sensors (21);

   wherein:

   - a calibration curve created for a specific airflow volume based on a plurality of different filter resistances and the respective corresponding pulse width modulation (PWM) ratio and the respective motor speed (n) is stored in a memory (14) of the electronic control system (5);

   - the direct current motor can be controlled in hood operating mode using the pulse width modulation ratio read from the calibration curve associated to the speed of rotation (n) measured after switching on in relation to the respective input resistance; and

   - a constant pulse width modulation (PWM) ratio specific to the respective type of mask can be used in mask operating mode regardless of the respective filter resistance;

   wherein

   - an identification means (19, 20) for detecting the respective head part connected and for setting the corresponding operating mode is assigned to the electronic control system (5).
2. The blow filter device according to claim 1, characterized in that the electronic control system (5) for monitoring the airflow volume comprises a display unit (15) for indicating if a predefined speed range (n_min<n<n_max) is exceeded or not reached and in that, if the input resistance changes over time in hood operating mode, the direct current motor (6) can be controlled with a new pulse width modulation ratio read from the calibration curve that corresponds to the new input resistance after switching the device off and on and an associated automatic calibration run.
3. The blow filter device according to claim 1 or 2, characterized in that Hall sensors (21) are provided in the direct current motor (6) for measuring the rotational speed.
4. The blow filter device according to claim 2, characterized in that the display unit (15) includes optical and/or acoustic signal elements (16, 17).
5. The blow filter device according to claim 1, characterized in that the identification means for detecting the respective connected head part is a sensing and control system integrated into an air outlet port (8) of the blow filter device (1) and connected to the electronic control system (5), said sensing and control system communicating with different designs of hose fittings (11) of the breathing hood (10) , the breathing mask, or different breathing masks and transmits a respective signal for hood or mask operating mode or different mask operating modes to the electronic control system (5).
6. The blow filter device according to claim 5, characterized in that the sensing and control system includes an identification switch (19) that takes one switching position when the hose fitting (11) of a breathing hood (10) is connected for hood operating mode, and another switching position when a breathing mask is connected to set the electronic control system to mask operating mode.
7. The blow filter device according to claim 6, characterized in that an actuating element (20) for setting the identification switch (19) to mask operating mode is provided in the hose fitting of the breathing mask.
8. The blow filter device according to claim 7, characterized in that the actuating element (20) has different designs according to the respective type of mask and that the identification switch (19) for mask operating mode can be set to different positions specific to the respective mask type using a respective mask type-specific pulse width modulation ratio stored in the electronic control system (5).
9. The blow filter device according to claim 8, characterized in that switch (19) for signaling the respective type of mask and setting the respective pulse width modulation ratio is a multipole switch.
10. The blow filter device according to claim 1, characterized in that the direct current motor (6), the electronic control system (5) and the display unit (15) are connected to an accumulator (12) via an on/off switch (18).

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