Note: Descriptions are shown in the official language in which they were submitted.
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l r~;S:iUKl:~;lJ PR~ lv~; MASK
~1VITH DEMAND-TYPE VENTII~TOR iHAVlNG
OPnMlZED ELECrRlCAL POWER CONSUMPTION
Technical Field
The present invention relates generally to the field of pressurized breathing
masks, and, more , L~ LIy~ to an ~ driven ventiiator which is operatively
arranged to ~ y maintain a pressure in the mask during various demanded fiow
conditions.
B~uh~uul~i Art
Various systems and equipment have been developed to provide breathing
protection against toxic agents in the I , ' ~;. Some of these systems are configured
as closed circuits. These are generally self-contained, and are arranged to supply either
oxygen or air, as necessary. These systems typically depend upon a volume of stored gas,
and are therefore often heavy.
Other systems, configured as open circuits, use various filters for fiitering
and/or processing the air chemically to provide breathable air.
Some systems use an electric ventiiator that .~ for some, if not
all, of the various pressure drops across the Elters, the valves, the mask, and the hoses.
These systems generally have a self-contained electrical power source (e.g., a battery), an
ZO ~l.octrir l~y powered blower or ventilator, one or more filters, and various hoses connect-
ing the ventilator to the person's mask or protective headgear. To avoid the entry of
toxic products into the mask, it is often desired to maintain the pressure vithin the mask
at a pressure greater than that of the atmosphere so that any leakage wiii tend to be
from the mask to the ~ILl~u~ rather than vice versa. By the same token, the wear-
er's respiration will vary with his activity. To ' hard and heavy breathirlg, aswhen the wearer is under u ull~ ai~l~ load, a powerful ventilator must be used. The
operation of such a ventilator places increased demands upon the electrical power
source. In addition to this, the filtering capacity of various filters typically diminishes in
a manner p~upu~iùl~d to the square of the flow of fiuid Lll~ ~ Lll~u_~,h. It is therefore
desirable to optimize the power . of such a ventilator-fiow system as much
as possible.
It has been proposed to provide a buffer volume, either in the form of a
bag placed near the mask or as a separate buffer volume, between the ventilator and the
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mask to absorb respiration peaics and to decrease the weight of portable electrical power
sources. However, these systems are believed to be heavy, ~ ' costly and frag-
iie.
European Patent No. 0 413 555 discloses a protective device having a pres-
S sure sensor arranged to provide r '- in the form of puises so as to maintain a
pressure within the mask. However, due to the range in the wearer's respiration, the
fact that different wearers have different physical . l, ~ and breathe differently
under various ~ , the system shown in this patent is believed to .
require powerful batteries.
European Patent No. 0 352 938 discloses a protective device that accommo-
dates partial clogging of filters by increasing the pressure supplied by the ventilator as
the ~ilter begins to clog.
European Patent No. 0 334 555 discloses a protective device having a venti-
lator. The input is closed at the beginning of an exhalation cycle, and is reopened at the
lS beginning of an inhalation cycle.
French Patent No. 81-09861 discloses a protective system having a two-
speed ventilator.
French Patent No. 91-10495 discloses a similar system capable of providing
an abnormal voltage for a ~,UI~ ,Li~ short period of time.
Disclosure of the Invention
The present invention broadly provides an improved mask that offers pro-
tection for various respiratory I ~ , against the i.~lU iU~,LiOII of toxic products.
The improved apparatus includes a supply or source of purified air or oxygen, an axial
or centrifugal ventilator which ~ for the pressure drop across the various
filters and other line lûsses, and a source of electrical power. The ventiiator motor is
minimally supplied with additional eiectrical energy to provide a large fiow to cover peak
inhalations of a man at rest, and to impose a minimum rotational speed on the ventila-
tor. This rotational speed may be greater than about 500 revolutions per minute, and is
~ ,., l; .... ~ly variable from this level up to the maximum speed of the motor. The appa-
30 ratus is aiso arranged to supply electrical energy to the ventilator motor so as to provide
a flow suOElcient to cover peak inhalations of a man undergoing strong, but not extreme,
physical activity. In this mode, the maximum rotor speed of the ventilator is typically not
greater than about 14,000 revolutions per minute. The apparatus may further include a
pressure sensor that permits continuous control of the amount of electrical energy pro-
35 vided tû the ventilator be~ween upper and lower limitr~, as a functiûn of the demand load
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pressure. The response time for the ventilator to change speeds is generally less than
one second.
Accordingly, the general object of this invention is to provide an improved
pressurized ventilator system with increased safety and reduced power,
Another object is to provide such a mask with a demand-type regulator.
Still another object is to provide such an improved mask and regulator, in
which the electrical power . of the ventilator is coupled to the demand load,
and is optimized.
These and other objects and advantages will become apparent from the
10 foregoing and ongoing written `1~ :ri 1;the drawings, and the appended claims.
Brief Description of the Drawines
Fig. 1 is a schematic view of the improved apparatus.
Fig. 2 is a ~ ~ y schematic vertical sectional view of the pressure
sensor shown in Fig. 1.
l~i Fig. 3 is a r C~ ' y schematic vertical sectional view of another form of
pressure sensor that might be used in Fig. 1.
Fig. 4 is a L. ~ y schematic vertical sectional view of a demand-type
regulator.
Fig. 5 is a L~b.~ L~I~y transverse vertical sectional view thereof, taken gen-
20 erally on line 5-5 of Fig. 4.
Description of the Preferred ~I..b~
At the outset, it should be clearly understood that like reference numerals
are intended to identify the same structural elements, portiorls or surfaces Wl~i~L~.llLIy
throughout the several drawings figures, as such elements, portions or surfaces may be
2~i further described or explained by the entire written ~ ,." of which this detailed
description is an integral part. Unless otherwise indicated, the drawings are intended to
be read (e.g., cross-hatching, ~..,- .~,. . .1 of parts, proportion, degree, etc.) together
with the ~ and are to be considered a portion of the entire written descrip-
tion of this invention. As used in the following tl~crrirtion~ the terms "horizontal, "verti-
30 car' left", "right, "up and "down, as well as adjectival and adverbial derivatives thereof(e.g., "horizontally, "r;bhL~u.dl~", "upwardly", etc.), simply refer to the orientation of the
illustrated structure as the particular drawing figure faces the reader. Similarly, the
terms "inwardly" and outwardly" generally refer to the orientation of a surface relative
to its axis oE elongation, or axis of rotation, as .l~J~JIU~
2139~2~
1
As used herein, the term "relative pressurer or "pressure differential" in the
mask is intended to broadly refer to the difference between the pressure within the
user's mask and the ambient ~ h ;~, pressure. A ~feeble activiLy" WllCi~JU~ to
the physical activity of a man at rest who is providing ' ' work of .~
S 15 watts. A "strong activity~ Wll~ /Ulld:~ to the physical activity of a man providing
mechanical work at ~ , 160 watts. An "extreme physical activiLy" Wll~yull~b
generally to physical activity of a man providing mechanical work of ~ 300
watts.
Turrling now to the drawings, the general purpose of this invention is to
10 provide a protective mask-Lype device Eor protecting the wearer against toxic products in
the aLI~Iu~ ; and which optimizes the use of various electrical I I More
particularly, this means that the size of various electrical power sources may be reduced,
and safety may be increased by reducing the maximum speed and flow oE gases passing
through various filters, all while optimizing respiratory comfort. The device also reduces
15 the response time of the sensor and ventilator to changes in the wearer's breathing level.
The device "~ -. for most, if not all, of the pressure drop across
various filters and tubing.
These goals are attained by the invention that is essentially .1-- ,.. I,.; . .1 by
providing a ventilator motor that is, I~, supplied with a minimum level of elec-
20 trical energy (El) in such a manner as to provide an adequate flow to cover the wearer'speak inhalation rate at rest, and to cause the ventilator to rotate at a minimum rotation-
al speed (Rl), typically greater than a~ V 500 revolutions per minute, so that
the time necessary to have the ventilator rotational speed track or follow changes in the
wearer's breathing, will take less than one second. To this end, the ventilator motor may
25 be supplied with electrical energy (Ez) in such a manner as to provide a flow sufficient
to cover the peak inhalation rate of a man undergoing strong, but not extreme, physical
activity, and to cause the ventilator to rotate at a maximum speed on the ventilator (R2)
less than about 14,000 revolutions per minute. The equipment may further include a
pressure sensor that controls the level of electrical energy between upper and lower
30 limits (E2) and (El) and rotational speeds between upper and lower limits (R2) and (Rl),
as a continuous function of the differential pressure across the mask. As previously
indicated, the response time of the sensor and ventilator to changes in the demand pres-
sure is typically less than one second.
According to one preferred manner o~ operating the apparatus, the pressure
35 sensor controls the electrical command signal supplied to the ventilator motor in the
following manner: (I) when the value of the pressure differential across the mask is less
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than the threshold pressure diEerential, ~P2 (typically between 0 and 1.5 hecto-pascal),
the electrical energy furnished to the ventilator is ' "~ constant and equal to E2
(typically between 4 and 25 watts), (2) when the value oE the pressure differential across
the mask is between ~P2 and l~PI (~P2 being less than ~PI) the electrical energy Eur-
5 nished to the ventilator is a continuous and decreasing Eunction of the relative pressurein the mask at an average slope of -0.01 to -1.0 hecto-pascal per watt, and (3) when the
value oE the relative pressure in the mask is greater than ~PI, the electrical energy Eur-
nished to the ventilator motor is ' "y constant and equal to (El), typically be-tween 0.05 and 4 watts.
According to another preferred method oE operation, the sensor will com-
mand the electrical energy level (E) provided to the ventilator in the Eollowing manner:
(1) when the pressure in the mask is less than the threshold diEerential ~P2 (typically
between 0 and 1.5 hecto-pascal), electrical energy supplied to the ventilator is substan-
tially constant and is equal to a maximum value (E2) (typically between 4 and 25 watts),
(2) when the pressure diEerential across the mask is between ~P2 and ~PI (~P2 being
less than ~PI), the electrical energy supplied to the ventilator motor is equal to some
value between El and E2) and (3) when the pressure diEerential across the mask is
greater than ~PI, the electrical energy supplied to the ventilator motor is ' "~constant and is equal to El (typically a value between 0.05 and 4 watts).
The electrical energy can be summed over time to End and determine the
electrical energy used over such period of time.
It is highly desirable Eor reasons of comfort and safety to the user, that the
ventilator follows the breathing demands of the user. This demand can become very
rapid, lla~ .ulally with exertion or; If the speed of the ventilator motor were
to start at zero, it would be impossible to overcome the inertial forces in order to rapidly
increase the ventilator Elow fast enough to follow the user's demand. Similarly, if the
ventilator motor were to be operated at too high a speed, the inertia of the rotating
parts would not allow the ventilator to reduce aOw rapidly enough to following the de-
mand variation in the exhalation aOw. This is very important, especially for fP~trjfllg~l
type ventilators that have speciE c nu . ,'~ u~ Indeed, when one closes
the outlet of a centrifugal ventilator, the speed of rotation tends to increase and the
electrical ~ . tends to decrease. This ~ can be used to maintain a
minimum rotation speed using little electrical energy, in order to reduce the response
time to changes in the wearer's respiratory cycle. Moreover, it is highly desirable that
the wearer knows the amount of electrical energy remaining in his batteries. Thus, ac-
cording to the preferred mode of operation, the consumed energy is summed over a
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period of time. The summed energy may be subtracted from an initial value such that
the amount of energy remaining in the batteries is displayed. If desired, an electrical
reset switch is arranged to "~ reset the display means at each battery change,
such that the initial level of charge within the batteries will be ."~ displayedS whenever they are changed.
According to another but still preferred mode of operation, the pressure
controller has two like ' mounted on the same structure. Aithough these
are very light, they do have a tanglble mass. When ' i, these mem-
branes have a tendency to move together and send a signal as if the chamber pressure
10 has changed. This l' introduces errors into the apparatus. To remedy this
situation, one typically places two identical ' so as to separate three volumes
V1, V2 and V3. Two of these three volumes l with one another. For exam-
ple, volume Vl and V2 may, with one another (as shown in Fig. 2). Aiter-
natively, volumes Vl and V3 may with one another, (as shown in Fig. 3).
15 The net signal supplied by the pressure sensor is the algebraic difference between the
two respective signals of each membrane. Thus, the eEects of the ~ ; on the
. ,1",. ,. ~ is eEectively cancelled. The invention also allows for ~ due to
.l.nul~ variations. The ' all~ may be i , ~ sensitive. Thus, by sub-
tracting the two output signals (ie., I = 11- l2? the i , ~ effects on each can be
20 cancelled. Thus, the improved device can be ~.. l.. ,.l ;....-~ , ' and/or tempera-
ture~ ----r
Referring now to the drawings, Fig. 1 depicts a mask I as . , ~ the
mouth and nose of a wearer 2. A connecting tube 3 l the mask with a
ventilator 4. A pressure sensor S positioned between the ventilator and the mask is
25 arranged to sense the pressure diEerential across the mask. Filter assemblies 6 are ar-
ranged to chemically filter incoming air. An electrical source 7 (typically one or more
batteries) is arranged to provide electrical power via an electronic controller 8 to the
ventilator motor. An indicator 9 is operatively arranged to display the remaining amount
of electrical energy in the battery. A reset switch 10 is arranged to cause the display to
30 indicate the fresh charge of new batteries, when they are replaced.
Referring now to Fig. 2, two ' 11, 12 are shown as subdividing a
chamber within a body into three volumes, Vl, V2 and V3. In this form, volumes V1 and
V2 with one another through an opening in membrane 11. Thus, the
pressures within volumes Vl and V2 are ' ",~ equal. In this particular case, the35 diEerential pressure between volumes Vl and V3, or V2 and V3, is equal to the algebraic
difference of îhe change of pressure indications given by the two 111~ 11~ or, E = I2 -
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Il.
In Fig. 3, volumes Vl and V3 are shown as v with one anoth-
er. Thus, the pressures in volumes Vl and V3 are ' "!~ equal. In this case, the
differential pressure existing between volumes V2 amd VD or between V1 and V2, is
' "~ equal to the algebraic difference of the individual indications given by the
two ' Or, I = I1 - I2
In Fig. 4, two ' 11, 12 are shown as separating volumes Vl, V2
and V3. In this form, volumes Vl and V3 . with one another. A spring 13
arranged within volume V2 keeps the two membranes 11, 12 apart. The two membranes
are connected via parts 14, 15, ~ iv~ly~ to a cap 16 and lever 17. Lever 17 is
adapted to rotate about an axis 18. A flexible pipe or conduit 19 provides the flow-to-
be-regulated. When the pressure in volume Vl is reduced, spring 13 spreads the two
11, 12 and opens valve 20 to allow the i~ u~ -., of pressurized fluid from
tube 19 into the chamber.
In the preEerred . ' ' t, the useful range of the pressure sensor may
be typically in the order of h~vm zero to about 4 millibar. The controller 8 provides a
minimum threshold of electrical energy El to the ventilator regardless of the value de-
termined by the sensor and above a certain maximum value, for example 1.5 millibar.
Similarly, controller 8 is arranged to provide a maximum energy level E2 to the ventilator
regardless of the value provided by the pressure sensor less than, for example, Q1 milli-
bar. Between these two pressure limits, the controller matches each value of pressure
v~ith a ~JIU~)UI Liui~al electrical energy, which is supplied to the ventilator at each distance.
In other words, between the two limits, the electrical energy supplied to the ventilator
motor is ~IUIJUlLiUll.ll to the demand flow. The controller 8 then sums and integrates
the energy supplied to the ventilator as a function of time. Display 9 allows one to see
the energy available by indicating the difference between the energy initially present and
the energy consumed. Thus, the displayed amount represents the amount of energy
remaining in the battery source. Switch 10 allows for ' of the counter by
presenting the initial value on the display when the batteries are installed or changed at
the beginning of the mission. This value may represent the energy in Joules, for exam-
ple, or the minimum number of hours remaining for self-contained operation at an ex-
pected average demand.
The invention has numerous .,~
Therefore, while several preferred L ' of the improved apparatus
have been shown and describcd, and several ' ~ thereof discussed, persons
skilled in this art vill readily appreciate that variûus additional changes and, ~ r, ~l i",~
2~397~
may be made without departing from the spirit of the inventiorl, as defined and differen-
tiated by the following claims.
