U.S. patent application number 13/647247 was filed with the patent office on 2013-02-07 for pump and exhalation valve control for respirator apparatus.
This patent application is currently assigned to COVIDIEN LP. The applicant listed for this patent is Covidien LP. Invention is credited to Carmeli Adahan.
Application Number | 20130032151 13/647247 |
Document ID | / |
Family ID | 42229675 |
Filed Date | 2013-02-07 |
United States Patent
Application |
20130032151 |
Kind Code |
A1 |
Adahan; Carmeli |
February 7, 2013 |
PUMP AND EXHALATION VALVE CONTROL FOR RESPIRATOR APPARATUS
Abstract
Double acting respirator pump apparatus including a pump member
reciprocable with respect to two pump chambers to deliver air to a
patient via a respirator exhalation system, which also facilitates
exhalation of the patient. The exhalation system has a pump unit
that is operatively connected to an exhalation valve member and
configured for selectively generating an air pressure sufficient
for pressurizing one side of the valve member for closing the same
when said exhalation system is operating in inhalation mode, and
may be operated for opening to allow the patient to exhale
therethrough.
Inventors: |
Adahan; Carmeli; (Jerusalem,
IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Covidien LP; |
Mansfield |
MA |
US |
|
|
Assignee: |
COVIDIEN LP
Mansfield
MA
|
Family ID: |
42229675 |
Appl. No.: |
13/647247 |
Filed: |
October 8, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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12314431 |
Dec 10, 2008 |
8303276 |
|
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13647247 |
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Current U.S.
Class: |
128/205.18 |
Current CPC
Class: |
A61M 16/0072 20130101;
A61M 16/0057 20130101; A61M 16/202 20140204; A61M 16/106 20140204;
A61M 16/1055 20130101; A61M 16/006 20140204; F04B 39/1046 20130101;
A61M 16/20 20130101; A61M 16/206 20140204; A61M 16/205
20140204 |
Class at
Publication: |
128/205.18 |
International
Class: |
A61M 16/00 20060101
A61M016/00; A61M 16/20 20060101 A61M016/20 |
Claims
1. Double acting respirator pump apparatus comprising a housing
defining two pump chambers and a pump member reciprocable with
respect to said pump chambers and configured to provide an inlet
stroke and an outlet stroke with respect to each said chamber in
each reciprocation cycle of said pump member, wherein said inlet
stroke and said outlet stroke for each pump chamber defines for the
respective pump chamber a displacement volume that is displaced in
the respective pump chamber by reciprocation of the pump member in
one reciprocation cycle between the respective inlet stroke and the
respective outlet stroke, and wherein a volume of at least one said
pump chamber at the end of the respective said output stroke
thereof is a first proportion of the respective said displacement
volume, wherein said first proportion is not less than about 50%,
and wherein said pump member comprises a piston reciprocably
mounted with respect to said pump chambers via a rolling
convolution diaphragm peripherally joined to the piston and
anchored with respect to each said pump chamber, and wherein said
diaphragm is configured for avoiding being collapsed during the
output stroke of each said pump chamber.
2. Pump apparatus according to claim 1, wherein said diaphragm is
configured to have a portion thereof that bulges in a direction
towards one said pump chamber and away from the other said pump
chamber regardless of a position of said piston within said
reciprocation cycle during operation of said pump.
3. Pump apparatus according to claim 1, comprising a pump inlet
port and a pump outlet port, wherein said pump inlet port is in
fluid communication with an inlet valve of at least one said pump
chamber via at least one inlet chamber having a first volume, and
wherein said pump outlet port is in fluid communication with an
outlet valve of at least one said pump chamber via at least one
outlet chamber having a second volume, and wherein each one of said
first volume and said second volume is at least a second proportion
of said displacement volume of said respective pump chamber,
wherein said second proportion is not less than about 50%.
4. Pump apparatus according to claim 3, wherein each said pump
chamber comprises a respective said inlet chamber and a respective
said outlet chamber, and wherein said outlet chamber of one said
chamber is in fluid communication with said outlet chamber of the
other said pump chamber, and wherein said inlet chamber of one said
chamber is in fluid communication with said inlet chamber of the
other said pump chamber.
5. Pump apparatus according to claim 1, wherein said diaphragm has
a convolution diameter that is between about 5% and about 15% of a
diameter of said piston as projected in said first direction.
6. Pump apparatus according to claim 5, wherein said diaphragm is
made from a flexible material, having a hardness of between about
50 Shore A and about 70 Shore A.
7. Pump apparatus according to claim 1, wherein said piston has an
axial translation in a reciprocation direction of said piston
between a top dead center position corresponding to an end of an
output stroke of one said pump chamber, and a bottom dead center
position corresponding to an end of an output stroke of the other
said pump chamber, wherein said axial translation is between about
10% and about 20% of a diameter of said piston.
8. Pump apparatus according to claim 1, wherein said piston is
driven by a motor by means of a crank and piston shaft
arrangement.
9. Pump apparatus according to claim 8, wherein said crank and
piston shaft arrangement are accommodated in a shaft housing in
fluid communication with one said pump chamber, and wherein said
motor is accommodated in a motor housing and operatively connected
to said crank in a manner providing for sealing of said respective
pump chamber within respect to said motor housing.
10. Pump apparatus according to claim 9, wherein said motor
comprises a driveshaft operatively connected to said crank, and
wherein said driveshaft is mounted with respect to said shaft
housing via a bearing arrangement, and wherein said bearing
arrangement comprises an integral seal for sealing said respective
pump chamber with respect to said motor housing.
11. Pump apparatus according to claim 4, wherein said housing
comprises a first end part including said inlet chamber and said
outlet chamber of one said pump chamber, a second end part
including said inlet chamber and said outlet chamber of the other
said pump chamber, a first cylinder part and a second cylinder
part, wherein said diaphragm is anchored between said first
cylinder part and said second cylinder part to define one said pump
chamber in each one of said first cylinder part and said second
cylinder part, and wherein said first end part and said second end
part are respectively mountable to said first cylinder part and
said second cylinder part.
12. Pump apparatus according to claim 4, comprising a pump inlet
port and a pump outlet port, wherein said pump inlet port is in
fluid communication with said inlet chamber of each said pump
chamber, and wherein said pump outlet port is in fluid
communication with said outlet chamber of each said pump
chamber.
13. Double acting respirator pump apparatus comprising a housing
defining two pump chambers and a pump member reciprocable with
respect to said pump chambers and configured to provide an inlet
stroke and an outlet stroke with respect to each said chamber in
each reciprocation cycle of said pump member, wherein said inlet
stroke and said outlet stroke for each pump chamber defines for the
respective pump chamber a displacement volume that is displaced in
the respective pump chamber by reciprocation of the pump member in
one reciprocation cycle between the respective inlet stroke and the
respective outlet stroke, and wherein a volume of at least one said
pump chamber at the end of the respective said output stroke
thereof is a first proportion of the respective said displacement
volume, wherein said first proportion is not less than about 50%,
and wherein said pump member comprises a piston reciprocably
mounted with respect to said pump chambers, wherein said piston has
a axial translation in a reciprocation direction of said piston
between a top dead center position corresponding to an end of an
output stroke of one said pump chamber, and a bottom dead center
position corresponding to an end of an output stroke of the other
said pump chamber, wherein said axial translation is between about
10% and about 20% of a diameter of said piston as projected in a
direction substantially orthogonal to said reciprocation
direction.
14. Respirator exhalation system for facilitating exhalation of a
patient connected to a respiratory apparatus, comprising an
exhalation valve and a pump unit that is operatively connected to
said exhalation valve and configured for selectively generating an
air pressure sufficient for pressurizing one side of said valve
member for closing the same when said exhalation system is
operating in inhalation mode.
15. Respirator system according to claim 14, wherein said pump unit
comprises a pump control member and a housing having a seat,
wherein a pumping chamber is defined between said pump control
member and said seat, wherein in operation of said pump unit said
pumping chamber comprises a confined volume of compressible air,
and wherein said pumping chamber is in fluid communication with a
control chamber comprising said valve member, and wherein said pump
unit is configured for selectively bringing said pump control
member into proximity with said housing seat to compress said
volume of compressible air and thereby to generate a pump pressure
for pressurizing said side of said valve member.
16. Respirator system according to claim 15, wherein said pump
control member comprises an armature, and said housing comprises an
electric coil, and wherein energizing said coil magnetically
attracts said armature to bring said pump control member into
proximity with said housing seat, thereby compressing air enclosed
in said pumping chamber and generating said pump pressure.
17. Respirator system according to claim 16, wherein said pump unit
is configured for modulating said pump pressure by selectively
variably energizing said coil.
18. Respirator system according to claim 16, wherein said armature
is connected to said housing seat via a flexible resilient
diaphragm, wherein said diaphragm is 15 configured for providing
substantially hysteresis-free operation of said pump unit.
19. Respirator system according to claim 18, wherein said diaphragm
extends between said armature and said housing seat, preventing
contact therebetween when said coil is fully energized and
providing for rapid separation therebetween when said coil is not
energized.
20. Respirator system according to claim 18, wherein said diaphragm
is biased to space said armature away from said housing seat when
said coil is not energized.
21. Respirator system according to claim 14, further comprising a
two-way control valve in fluid communication with said pumping
chamber and said side of said valve member, and configured for
selectively venting said side of said valve member.
22. Respiratory apparatus comprising the respiratory pump as
defined in claim 1 operatively connected to a respirator exhalation
system for facilitating exhalation of a patient connected to said
respiratory apparatus.
23. Respiratory apparatus comprising a respiratory pump apparatus
for delivering pressurized gas to a patient connected to said
respiratory apparatus, the respiratory pump apparatus being
operatively connected to a respirator exhalation system as defined
in claim 14.
Description
RELATED APPLICATION
[0001] The present application is a Continuation of co-pending U.S.
patent application Ser. No. 12/314,431 filed on Dec. 10, 2008, the
contents of which are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to pumps, and particularly to
pumps useful in respirator or ventilator apparatus. The invention
also relates to an exhalation valve assembly useful in such pumps
and respirator or ventilator apparatus.
BACKGROUND OF THE INVENTION
[0003] Respirator apparatus, sometimes called ventilator apparatus
and interchangeably referred to thus herein, is widely used for
administering artificial respiration or ventilatory assistance to a
patient.
[0004] By way of general background, the following US patents
disclose examples of such an apparatus, or of a pump and/or
exhalation valve useful in such apparatus.
[0005] U.S. Pat. No. 4,807,616, 4,823,787 and 4,941,469 disclose a
ventilator apparatus comprising a pump; a delivery conduit for
delivering pressurized air to a patient; a relief valve preventing
the pressure in the delivery conduit from rising above a
predetermined peak value; a sensor for sensing the pressure in the
delivery conduit; a storage device for storing the sensed peak
pressure; and a comparator for continuously comparing the sensed
pressure with the stored peak pressure and effective to energize
the pump whenever the sensed pressure is below the stored peak
pressure, and to deenergize the pump whenever the sensed pressure
is generally equal to the stored peak pressure.
[0006] U.S. Pat. No. 6,073,630, U.S. Pat. No. 5,484,270 and U.S.
Pat. No. 5,683,232 disclose a reciprocating pump particularly
useful in ventilator apparatus, and includes a piston
reciprocatable axially within a cylinder and dividing its interior
into an inlet chamber and an outlet chamber, a wall fixed within
the inlet chamber, and a drive housing fixed to the wall. The drive
housing includes a motor, a rotor rotatable by the motor, a nut
rotatable within the drive housing, and a screw threadedly coupled
at one end to the nut and fixed at its opposite end to the piston.
The piston is substantially unrestrained for axial and rotary
movement such that forward and reverse rotation of the nut by the
motor reciprocates the screw and the piston axially of the
cylinder, and also permits the screw and the piston to rotate with
respect to the cylinder to thereby even out wear between the piston
and cylinder.
[0007] U.S. Pat. No. 6,283,122 discloses an exhalation assembly
which includes a hollow flow-through body, having an air inlet port
and an air outlet port. The inlet port is arranged to receive air
for supplying to a patient, and the air outlet port is arranged to
provide air to a patient. The device also includes an exhalation
valve connected to the flow-through body, for facilitating
selectable exhalation by a patient to whom air is being supplied.
The exhalation valve includes an air exhalation port arranged to
permit therethrough an outflow of exhaled air and a valve member
arranged to selectably cover the exhalation port in response to a
closure pressure applied thereto, and to uncover the exhalation
port in response to an exhalation pressure applied thereto from the
flow-through body through the exhalation port Also included is a
pressure source for selectably applying a closure pressure to the
valve member, wherein the valve member is operative to cover the
exhalation port in response to at least a minimum closure pressure
which has a smaller magnitude than an opposing exhalation
pressure.
[0008] Further by way of general background, U.S. Pat. No.
5,762,480 discloses a reciprocating machine that converts linear
motion to rotary motion or vice-versa and is associated with a
supply of working fluid, and includes rotational power apparatus
having a rotational motion transfer member; a cylinder defining a
longitudinal axis and having a first end at which are located
working fluid input and output apparatus, and further having a
second end; a piston located within the cylinder and arranged for
linear, reciprocating travel along the longitudinal axis between
the first and second ends; a connecting rod having a first end
connected to the piston, and further having a second end portion;
and linkage apparatus.
SUMMARY OF THE INVENTION
[0009] According to one aspect of the present invention, there is
provided a pump apparatus, particularly useful for a respirator
apparatus, the pump apparatus being a double acting respirator pump
apparatus comprising a housing defining two pump chambers and a
pump member reciprocable with respect to said pump chambers and
configured to provide an inlet stroke and an outlet stroke with
respect to each said chamber in each reciprocation cycle of said
pump member, wherein said inlet stroke and said outlet stroke for
each pump chamber defines for the respective pump chamber a
displacement volume that is displaced in the respective pump
chamber by reciprocation of the pump member in one reciprocation
cycle between the respective inlet stroke and the respective outlet
stroke, and wherein a volume of at least one said pump chamber at
the end of the respective said output stroke thereof is a first
proportion of the respective said displacement volume, wherein said
first proportion is not less than about 50%, and wherein said pump
member comprises a piston reciprocably mounted with respect to said
pump chambers via a rolling convolution diaphragm peripherally
joined to the piston and anchored with respect to each said pump
chamber, and wherein said diaphragm is configured for avoiding
being collapsed or reversed during the output stroke of each said
pump chamber.
[0010] The pump apparatus according to this aspect of the invention
may comprise one or more of the following features A to K, in any
desired combination:
[0011] (A) The diaphragm may be configured to have a portion
thereof that bulges in a direction towards one said pump chamber
and away from the other said pump chamber regardless of a position
or direction of travel of said piston within said reciprocation
cycle during operation of said pump.
[0012] (B) The pump comprises a pump inlet port and a pump outlet
port, wherein said pump inlet port is in fluid communication with
an inlet valve of at least one pump chamber via at least one inlet
chamber having a first volume, and wherein said pump outlet port is
in fluid communication with an outlet valve of at least one pump
chamber via at least one outlet chamber having a second volume, and
wherein each one of said first volume and said second volume is at
least about 50% of said displacement volume of said respective pump
chamber.
[0013] (C) Referring to feature (B), each said pump chamber may
comprise a respective said inlet chamber and a respective said
outlet chamber, and wherein said outlet chamber of one said chamber
is in fluid communication with said outlet chamber of the other
said pump chamber, and wherein said inlet chamber of one said
chamber is in fluid communication with said inlet chamber of the
other said pump chamber.
[0014] (D) The diaphragm may have a convolution diameter, i.e., a
projected dimension along a first direction substantially
orthogonal to a reciprocation direction of said piston, that is
between about 5% and about 15% of a diameter of said piston.
[0015] (E) Regarding feature (D), the diaphragm may be made, for
example, from a flexible material, having a hardness of between
about 50 Shore A and about 70 Shore A. For example, such a flexible
material may be a rubber-based compound.
[0016] (F) The piston may have an axial displacement in a
reciprocation direction of said piston between a top dead center
position corresponding to an end of an output stroke of one said
pump chamber, and a bottom dead center position corresponding to an
end of an output stroke of the other said pump chamber, wherein
said axial displacement or translation that is between about 10%
and about 20% of a diameter of said piston as projected in a
direction substantially orthogonal to said reciprocation
direction.
[0017] (G) The piston is driven by a motor by means of a crank and
piston shaft arrangement.
[0018] (H) Regarding feature (G), the crank and piston shaft
arrangement may be accommodated in a shaft housing in fluid
communication with one said pump chamber, and wherein said motor is
accommodated in a motor housing and operatively connected to said
crank in a manner providing for sealing of said respective pump
chamber within respect to said motor housing.
[0019] (I) Regarding feature (H), the motor may comprise a
driveshaft operatively connected to said crank, and said driveshaft
is mounted with respect to said shaft housing via a bearing
arrangement, wherein said bearing arrangement comprises a seal for
sealing said respective pump chamber within respect to said motor
housing. Such a seal may be an integral seal, i.e., integral to the
motor shaft bearing.
[0020] (J) Regarding at least feature (C), the housing may comprise
a first end part including said inlet chamber and said outlet
chamber of one said pump chamber, a second end part including said
inlet chamber and said outlet chamber of the other said pump
chamber, a first cylinder part and a second cylinder part, wherein
said diaphragm is anchored between said first cylinder part and
said second cylinder part to define one said pump chamber in each
one of said first cylinder part and said second cylinder part, and
wherein said first end part and said second end part are
respectively mountable to said first cylinder part and said second
cylinder part.
[0021] (K) Regarding at least feature (C), the apparatus comprises
a pump inlet port and a pump outlet port, wherein said pump inlet
port is in fluid communication with said inlet chamber of each said
pump chamber, and wherein said pump outlet port is in fluid
communication with said outlet chamber of each said pump
chamber.
[0022] It is to be noted that feature (J) is considered per se
novel, and applicable mutatis mutandis to other types and
configurations of pumps.
[0023] It is also to be noted that feature (I) is considered per se
novel, and applicable mutatis mutandis to other types and
configurations of pumps.
[0024] According to another broad aspect of the present invention,
there is provided a pump apparatus, particularly useful for a
respirator apparatus, the pump apparatus being a double acting
respirator pump apparatus comprising a housing defining two pump
chambers and a pump member reciprocable with respect to said pump
chambers and configured to provide an inlet stroke and an outlet
stroke with respect to each said chamber in each reciprocation
cycle of said pump member, wherein said inlet stroke and said
outlet stroke for each pump chamber defines for the respective pump
chamber a displacement volume that is displaced though the
respective pump chamber by reciprocation of the pump member in one
reciprocation cycle between the respective inlet stroke and the
respective outlet stroke, and wherein a volume of at least one said
pump chamber at the end of the respective said output stroke
thereof is not less than about 50% of said displacement volume, and
wherein said pump member comprises a piston reciprocably mounted
with respect to said pump chambers, wherein said piston has a axial
displacement or translation in a reciprocation direction of said
piston between a top dead center position corresponding to an end
of an output stroke of one said pump chamber, and a bottom dead
center position corresponding to an end of an output stroke of the
other said pump chamber, wherein said axial translation is between
about 10% and about 20% of a diameter of said piston as projected
in a direction substantially orthogonal to said reciprocation
direction.
[0025] The pump apparatus according to this aspect of the invention
may comprise one or more of the features B, C, and F to K listed
above, in any desired combination.
[0026] According to a broad aspect of the present invention, there
is provided a pump apparatus, particularly useful for a respirator
apparatus, the pump apparatus comprising a housing defining a two
pump chambers and a piston reciprocable with respect to said pump
chambers and configured to provide an inlet stroke and an outlet
stroke with respect to each said chamber in each reciprocation
cycle of said piston, wherein said piston is reciprocably mounted
to said housing via a rolling convolution diaphragm peripherally
joined to said piston and anchored with respect to each said
chamber.
[0027] The pump apparatus according to this aspect of the invention
may comprise one or more of the features A to K listed above, in
any desired combination.
[0028] According to another broad aspect of the present invention,
there is provided a pump apparatus, particularly useful for a
respirator apparatus, the pump apparatus comprising a housing
defining a two pump chambers and a pump member reciprocable with
respect to said pump chambers and configured to provide an inlet
stroke and an outlet stroke with respect to each said chamber in
each reciprocation cycle of said piston, wherein said housing
comprises a first end part including said inlet chamber and said
outlet chamber of one said pump chamber, a second end part
including said inlet chamber and said outlet chamber of the other
said pump chamber, a first cylinder part and a second cylinder
part, wherein said pump member is mounted for reciprocation with
respect to said first cylinder part and said second cylinder part
to define one said pump chamber in each one of said first cylinder
part and said second cylinder part, and wherein said first end part
and said second end part are respectively mountable to said first
cylinder part and said second cylinder part.
[0029] For example, the pump member may comprise a piston that is
reciprocably mounted to said housing via a rolling convolution
diaphragm peripherally joined to said piston and anchored with
respect to each said chamber, wherein said diaphragm is anchored
between said first cylinder part and said second cylinder part.
[0030] The pump apparatus according to this aspect of the invention
may comprise one or more of the features A to K listed above, in
any desired combination, as appropriate.
[0031] At least some embodiments of the pump apparatus according to
at least one of the above aspects of the invention provides one or
more features, including inter alia, noise reduction, easy
assembly, disassembly and replacement of parts.
[0032] According to another broad aspect of the invention there is
provided a respirator exhalation system for facilitating exhalation
of a patient connected to a respiratory apparatus, comprising an
exhalation valve and a pump unit that is operatively connected to
said exhalation valve and configured for selectively generating an
air pressure sufficient for pressurizing one side of said valve
member for closing the same when said exhalation system is
operating in inhalation mode.
[0033] The respirator exhalation system comprises an exhalation
valve assembly comprising a delivery tube comprising an inlet port
for connection to a respiratory pump apparatus, an outlet port for
connection to a patient, an exhalation valve discharge port leading
to the atmosphere, and the valve member for alternately connecting
the outlet port to one or another of said inlet port and said
exhalation port, under the action of the respirator exhalation
system.
[0034] The pump unit may comprise a pump control member and a
housing having a seat, wherein a pumping chamber is defined between
said pump control member and said seat, wherein in operation of
said pump unit said pumping chamber comprises a confined volume of
compressible air, and wherein said pumping chamber is in fluid
communication with a control chamber comprising said valve member,
and wherein said pump unit is configured for selectively bringing
said pump control member into proximity with said housing seat to
compress said volume of compressible air and thereby to generate a
pump pressure for pressurizing said side of said valve member.
[0035] The pump control member may comprise an armature, and said
housing may comprise an electric coil, and wherein operation of the
pump unit energizes said coil and magnetically attracts said
armature to bring said pump control member into proximity with said
housing seat, thereby compressing air enclosed in said pumping
chamber and generating said pump pressure.
[0036] The armature is connected to said housing seat via a
flexible resilient diaphragm, wherein said diaphragm is configured
for providing substantially hysteresis-free operation of said pump
unit.
[0037] The diaphragm may extend between the armature and the
housing seat, preventing contact therebetween when the coil is
fully energized and providing for rapid separation therebetween
when said coil is not energized, i.e., as soon as the coil stops
being energized.
[0038] The diaphragm may be biased to space the armature away from
the housing seat when the coil is not energized.
[0039] The pump unit may be configured for modulating the pump
pressure by selectively variably energizing the coil. For example,
the pump control member may be modulated to relieve the pressure
acting on said side of the valve member of said exhalation valve at
any desired preset pressure.
[0040] The respirator system may further comprise a two-way control
valve in fluid communication with said pumping chamber and said
side of said valve member, and configured for selectively venting
said side of said valve member.
[0041] According to another broad aspect of the invention, there is
provided a respiratory apparatus comprising the respiratory pump
according to other aspects of the invention as defined herein,
operatively connected to a respirator exhalation system for
facilitating exhalation of a patient connected to said respiratory
apparatus.
[0042] According to yet another broad aspect of the invention,
there is provided a respiratory apparatus comprising a respiratory
pump apparatus for delivering pressurized gas to a patient
connected to said respiratory apparatus, the respiratory pump
apparatus being operatively connected to a respirator exhalation
system, according to aspects of the invention as defined
herein.
[0043] At least some embodiments of the respirator system of the
present invention have one or more of the following features.
[0044] The pump unit enables the valve member to be closed quickly,
during the inhalation cycle, independently of the action of the
respirator pump apparatus, and thus minimizes escape of air through
the respirator exhalation system when the pump apparatus begins the
inhalation cycle. This enables the pump apparatus to deliver a
volume of air to the patient as required, and minimizes leaks which
could otherwise be significant, particularly when delivering small
amounts of air or when inhalation breaths are delivered at high
frequency, for example to babies.
[0045] The provision of a two-way control valve increases the
reliability of the respirator exhalation system, and avoids
failures of equipment. In a respirator the failure of a valve to
allow exhalation will result in suffocation of the patient,
accordingly two valves perform the release of the exhalation valve
simultaneously such that failure of one will not prevent
exhalation.
[0046] At least some embodiments of the invention are directed to a
double acting respirator pump apparatus including a pump member
reciprocable with respect to two pump chambers to deliver air to a
patient via a respirator exhalation system, which also facilitates
exhalation of the patient. The exhalation system has a pump unit
that is operatively connected to an exhalation valve member and
configured for selectively generating an air pressure sufficient
for pressurizing one side of the valve member for closing the same
when said exhalation system is operating in inhalation mode, and
may be operated for opening to allow the patient to exhale
therethrough.
BRIEF DESCRIPTION OF THE DRAWINGS
[0047] In order to understand the invention and to see how it may
be carried out in practice, embodiments will now be described, by
way of non-limiting example only, with reference to the
accompanying drawings, in which:
[0048] FIG. 1 schematically illustrates in cross-sectional view, a
system including a pump and exhalation valve assembly according to
an embodiment of the invention, in which the exhalation valve
assembly is operating in inhalation mode.
[0049] FIG. 2 schematically illustrates in cross-sectional view,
the embodiment of the exhalation valve assembly of FIG. 1, in which
the exhalation valve assembly is operating in exhalation mode.
DETAILED DESCRIPTION OF EMBODIMENTS
[0050] Referring to FIGS. 1 and 2, a respirator apparatus according
to according to an embodiment of the invention, designated with
reference numeral 600, comprises pump 100 and exhalation valve
assembly 200.
[0051] The pump 100 includes a housing 110 comprising a first end
20, a cylinder 120, and a second end 23. The first end 20 comprises
an inlet port 14 and an outlet port 17, and the inlet port 14 may
comprise a filter (not shown) for removing solid particles from the
air that is inletted into the housing. In variations of this
embodiment the filter may be omitted altogether, while in other
variations of this embodiment a bacterial filter may be
additionally or alternatively provided to filter contaminants such
as bacteria, for example, and such a bacterial filter may be
provided between the outlet 17 and hose 50, for example.
[0052] In use, the inlet port 14 may be in fluid communication with
the atmosphere, directly or via a filter, or alternatively may be
connected via a suitable coupling to an 5 oxygen source or an
oxygen enriched air source.
[0053] The outlet port 17 receives hose 50 for coupling the outlet
port 17 to the exhalation valve assembly 200.
[0054] The cylinder 120 has a longitudinal axis 199, and is closed
at each longitudinal end by respective partition walls 122 and 124
to define an internal chamber 125. In this embodiment, the cylinder
is constructed from two parts: cylinder part 21 comprises about
half of the length of the cylinder 120 plus partition wall 122, and
the other cylinder part 22 comprises the remainder of the cylinder
120 plus partition wall 124. Cylinder parts 21 and 22 may each be
made as integral items, or alternatively from separate components
joined together in a suitable manner at join plane 129.
[0055] An anchored piston arrangement 150 includes a piston 4 and a
peripheral convolution diaphragm 5 joined thereto. A piston rod 3
is attached to the piston arrangement 150 at one side of the piston
4, extending out of the chamber 125 via an opening 126 in partition
wall 124. The peripheral diaphragm 5 has an inner peripheral lip or
bead 152 that is sealingly received into a peripheral recess 151
provided at the edge of the piston 4, and an outer peripheral lip
or bead 18 that is sealingly received at an annular recess 153
provided in the cylindrical wall 155 of the cylinder 120. In this
embodiment, the annular recess 153 is located axially where the
cylinder parts 21, 22 meet, at or close to plane 129.
[0056] Thus, the outer peripheral end of the piston arrangement 150
is sealingly anchored at a fixed axial position in the cylinder
120, while allowing for reciprocable operation of the remainder of
the piston arrangement 150, by virtue of piston axial displacement
and rolling of the diaphragm 5, as will be described below in more
detail, with respect to axis 199. The piston arrangement 150
divides the internal chamber 125 into two chambers 8 and 9, which
are of variable volume according to the position of the piston 4
and the diaphragm 5 therein in a reciprocation cycle thereof, and
the outer peripheral end of the diaphragm 5, is sealingly anchored
with respect to each pump chamber 8, 9.
[0057] Partition wall 122 is in abutment with end 20 of the housing
110, and comprises a one-way inlet valve 132 and a one-way outlet
valve 134 with respect to chamber 9. Inlet valve 132 when open is
in fluid communication with the inlet port 14 via inlet chamber 12,
and outlet valve 134 when open is in fluid communication with the
outlet port 17 via outlet chamber 15. Chambers 12 and 15 are
integrally formed at end 20 of the housing 110, and are separated
from one another by partition 133.
[0058] The second end 23 comprises inlet chamber 13 and outlet
chamber 16, separated from one another by means of shaft chamber
162 of motor housing 160. Inlet conduit 10 connects and provides
fluid communication between inlet chamber 13 and inlet chamber 12,
while outlet conduit 11 connects and provides fluid communication
between outlet chamber 16 and outlet chamber 15.
[0059] As will become clearer below, inlet chambers 12 and 13, and
outlet chambers 15 and 16, each function as muffler chambers to
reduce noise generated by the pump 100, and each of these chambers
has an internal dimension that is larger than the opening(s)
thereto, in particular providing at least some wall surfaces
opposite the corresponding inlet valve or outlet valve of the
respective pump chamber 8 or 9.
[0060] Partition wall 124 is in abutment with end 23 of the housing
110, and comprises a one-way inlet valve 142 and a one-way outlet
valve 144 with respect to the chamber 8. Inlet valve 142 when open
is in fluid communication with the inlet port 14 via inlet chamber
13, conduit 10 and chamber 12, and outlet valve 134 when open is in
fluid communication with the outlet port 17 via chamber 16, conduit
11 and chamber 15.
[0061] Motor housing 160 is integrally formed with end 23, and
comprises a motor chamber 164, in which a rotary motor 1 is
accommodated, the output shaft 165 thereof passing through an
aperture 166 into shaft chamber 162 via bearing 19, which comprises
a suitable sealing arrangement 169 for preventing pressurized air
from other parts of the pump 100, in particular from chamber 8,
passing through the shaft chamber 162 and escaping through the
motor chamber 164 to the atmosphere. A cap 167 closes motor chamber
164. Typically, the motor is an electric motor.
[0062] Piston rod 3 is accommodated in chamber 162, and is
connected to crank 2, which is in turn mounted to the output shaft
165 also in chamber 162. No sealing is required between pump
chamber 8 and chamber 162, nor between the piston shaft 3 and
chamber 162 or pump chamber 8--rather, sealing of the pump chamber
8 with respect to the piston shaft 3 is effectively accomplished
further downstream, via the sealing arrangement 169.
[0063] In operation, a suitable power source (not shown) is
operatively connected to the motor 1 for providing power thereto,
and suitable monitoring and controlling apparatus may also be
connected to the pump 100, for example a transducer may be
connected to outlet 17, for monitoring and controlling the output
of the pump 100. Such a power source may include, for example,
electrical batteries and/or an electrical mains supply.
[0064] The pump 100 operates as a dual acting pump, and is thus
configured to produce two output strokes for each reciprocatory
cycle of piston 4. As the motor 1 is operated to turn output shaft
165, crank 2 reciprocates the piston rod 3, inducing linear
reciprocating travel along axis 199 of the piston 4 between a top
dead center position (TDC) and a bottom dead center position (BDC).
Concurrently, the piston 4 reciprocably drives the convolution
diaphragm 5 along axis 199 with respect to chamber 9, alternately
drawing in air through inlet valve 132 (via inlet port 14 and inlet
chamber 12) into pump chamber 9 in an input stroke, and displacing
a volume V of air through outlet valve 134 to outlet port 17 (via
outlet chamber 15) in an output stroke, and, with respect to
chamber 8, also alternately drawing in air through inlet valve 142
(via inlet port 14, chamber 12, inlet conduit 10 and chamber 13)
into pump chamber 8 in an input stroke thereof and displacing
another volume V of air through outlet valve 144 to outlet port 17
(via outlet chamber 16, outlet conduit 11, outlet chamber 15) in
the output stroke thereof. Operation of chamber 8 is in reverse
relationship to operation of chamber 9, and thus the input stroke
of one chamber 8 occurs concurrently with the output stroke of the
other chamber 9, and vive versa. In each output stroke of the
respective chamber 8 or 9, the air or gas in the respective chamber
becomes pressurized above the delivery pressure (e.g. above
ambient) and thus the respective drawn volume V of air is delivered
in a pressurized manner to the output port 17. Thus, continuous
operation of the reciprocating piston arrangement 150 generates a
continuous airflow, and each incremental rotation of the motor
results in a corresponding incremental delivery of pressurized air
via outlet 17.
[0065] The convolution diaphragm 5 is of the rolling type, and may
be made from rubber or other suitable flexible materials, for
example. The convolution diaphragm 5 is fitted in the cylinder 120
adopting a configuration wherein an outer peripheral part of
convolution diaphragm 5 proximal to bead 18 is in abutment with a
corresponding portion of the cylindrical wall close to recess 153,
and an inner peripheral part of the convolution diaphragm 5
proximal to bead 152 adopts a bulging configuration with the piston
4 throughout full reciprocal translation of the piston 4, having a
convex surface 5a (i.e., the surface having a generally convex
cross-section) facing chamber 9 and a concave surface 5b (i.e., the
surface having a generally concave cross-section) facing chamber 8.
As the piston 4 travels from the TDC position to the BDC position,
the outer peripheral part of the convolution diaphragm 5 unrolls
and progressively adopts the bulging configuration, while the inner
peripheral part of the convolution diaphragm 5 progressively adopts
a generally cylindrical configuration. Thus in every reciprocation
cycle, one or another part of the convolution diaphragm 5 is always
bulging in the same axial direction, always in the direction
towards chamber 9. It is to be noted that the diaphragm 5 may
instead be configured to be always bulging in the direction of
chamber 8 (rather than chamber 9), and thus even when chamber 8 is
in its output stroke the diaphragm 5 does not collapse. Thus, the
direction or pump chamber in which the diaphragm 5 is bulging
towards is fixed during operation of the pump.
[0066] While the convolution diaphragm 5 is thus sufficiently
flexible to roll over itself in both axial directions along axis
199 in each reciprocation cycle to roll the bulging part from one
peripheral end to another peripheral end of the diaphragm 5, and
the diaphragm 5 is at the same time configured to avoid collapsing
of the bulging part of the diaphragm 5 when pressure is applied to
the convex side 5a, such as during the output stroke of pump
chamber 9 and the air therein is being pressurized. In this
embodiment this is achieved by maintaining the cross-section of the
diaphragm small, i.e., using a diaphragm having a small convolution
radius and in a compact U-shape, while making the diaphragm from a
relatively flexible material, for example a rubber compound, having
a hardness of between about 50 and about 70 Shore A, for example.
The relatively small cross-section of the diaphragm 5, as compared
to the dimensions of the piston 4, together with the rigidity of
the diaphragm 5, help to center the piston 4 within the cylinder
120 and thus along axis 199. While the diaphragm 5 is sufficiently
flexible for rolling and unrolling in either direction along axis
199, the generally arcuate and relatively small cross-section
thereof provides a resistance to collapsing immediately when
subjected to a positive pressure on the convex side 5a.
[0067] In this embodiment, collapse of the diaphragm 5 is avoided
completely in the outlet stroke of chamber 9, and this is
facilitated by configuring the piston 4, which is substantially
rigid, to take up the majority of the pressurized area of the
piston arrangement 150. In particular, the convolution diameter t
of the diaphragm 5 is between about 5% and about 15% of the
diameter D of piston 4, wherein the convolution diameter t is taken
as half the linear difference between the diameter Dui of
cylindrical wall 155 and the diameter D of the peripheral edge of
the piston 4. Thus, the diameter Dui of the cylinder 120 at plane
129 is (2*t+D). This configuration confines the diaphragm 5 to a
relatively narrow annular region or space at the extremity of the
piston 4, and thereby applies a rigidity to the diaphragm 5
sufficient to prevent it from collapsing, and inverting so that it
bulges in the opposite direction, under the positive pressure of
the output stroke acting on the diaphragm 5. In operation, the
piston 4 may be considered to essentially "float", in a manner of
speaking, between the TDC and the BDC positions, and the diaphragm
5 thus acts as a bearing for the piston 4. Thus, unlike piston/seal
arrangements which slide in a cylinder inducing some friction
between the piston seal rings and the cylinder, the rolling
diaphragm 5 provides almost no friction or resistance to the
reciprocating movement of piston 4, while maintaining a complete
seal between the two sides of the piston 4, and thus between pump
chambers 8 and 9.
[0068] At least some embodiments of the present invention are
characterized by providing noise reduction features for the pump.
For example, in this embodiment, the pump chambers 8 and 9 each
comprise a relatively large minimal volume, when the piston 4 is at
the BDC or TDC position, respectively, and each such minimal volume
is larger than about 50% of the volume displaced or swept by the
piston 4 during translation between BDC and TDC, herein referred to
as the swept volume of the piston 4. This additional minimal volume
in each chamber 8, 9, while contributing to a reduction in pump
efficiency, nevertheless results in a moderate pressure change in
each of chambers 8 and 9 at their respective output strokes as the
piston 4 reaches BDC and TDC positions, respectively, and reverses
its travel direction thereat. The more moderate the pressure
change, the less abruptly the corresponding inlet and outlet valves
of the respective chambers open and close, thereby reducing noise
levels produced by the valves. Of course, the said one-way inlet
valves and outlet valves are configured for duly opening and
closing taking into account these moderate pressurization levels.
In alternative variations of this embodiment, the aforesaid minimal
volumes of chambers 8 and 9 beyond the TDC and BDC positions may be
substantially greater than about 50% the swept volume of the piston
4, and may each be for example any one of about 75%, 100%, 125%,
150% or greater than 150% of the swept volume of the piston 4.
[0069] Noise reduction is further enhanced in this embodiment by
providing inlet chambers 12 and 13, and outlet chambers 15 and 16,
each of which in this embodiment has an internal volume at least
about 50% of the swept volume of the piston 4. In alternative
variations of this embodiment the internal volume of one or both
inlet chambers 12, 13 and/or one or both of the outlet chambers 15,
16, may each be greater than about 50%, for example any one of
about 75%, 100%, 125%, 150% or greater than 150% of the swept
volume of the piston 4. Chambers 12, 13 thus act as mufflers to
prevent a significant proportion of the noise produced by the
opening and closing of valves 132 and 142, from exiting via the
inlet port 14, and chambers 15, 16 similarly act as mufflers to
prevent a significant proportion of the noise produced by the
opening and closing of valves 134 and 144, from exiting via the
outlet port 17. In particular, each chamber 12, 13, 15, 16 may be
designed for noise cancellation of the sound waves generated by the
corresponding valves, wherein the reflected sound waves diffuse the
generated sound waves.
[0070] At least some embodiments of the present invention are
further characterized by constructional parameters of the piston.
For example, in this embodiment, the relatively small translation
of the piston 4 from TDC to BDC allows the use of a smaller
diaphragm convolution than would otherwise be the case, increasing
its resistance to collapsing under a positive pressure force acting
on its convex surface 5a, as well as minimizing its wear. Thus, the
volumetric displacement V produced by the pump 100 is accomplished
by use of a piston arrangement having a relatively large surface
area normal to axis 199, while having a relatively small piston
translation r. Further, in this embodiment, the ratio D/r of the
piston diameter D to the piston translation r is at least about 5,
and optimally may be set at any suitable value between about 5 and
about 10, though in alternative variations of this embodiment the
ratio D/r may be greater than 10. Reducing the axial displacement r
too much may require a very large piston diameter D to provide the
required swept volume of the piston 4. While this increases the
ratio D/r, the resulting larger size of the piston may introduce
vibration problems due to the increased piston mass, as well as
increase the overall size of the pump 100. On the other hand,
increasing r results in increasing the stroke of the piston 4,
i.e., the axial displacement between TDC and BDC, which in turn
requires a longer diaphragm convolution to accommodate the
increased stroke. Thus, in practice all these factors are
considered for a particular design of pump 100, to arrive at the
optimum value of D/r therefor.
[0071] At least some embodiments of the present invention are
further characterized by constructional layout of the pump. For
example, in this embodiment, the pump housing 110 is assembled from
essentially four sections: the first end 20, cylinder parts 21 and
22, and the second end 23, stacked together with respect to axis
199, and each section is sealed with respect to an adjacent section
via respective 0-ring seals 24 disposed between each adjacent pair
of sections. In this embodiment, the bead 18 also acts as a seal,
and thus connection of the two cylinder parts 21, 22 does not
require an additional seal. While the conduits 10 and 11 are
illustrated in FIG. 1 as being separate components which are
connected to the ends 20 and 23, the conduits 10, 11 may be formed
within the walls of the cylinder parts 21, 22, and connect to the
respective inlet and outlet chambers. Thus, stacking the first end
20, cylinder parts 21 and 22, and the second end 23, will result in
the connection of both inlet chambers on the one hand, and of both
outlet chambers on the other hand. This simple constructional
layout may be considered as modular in form, and allows for low
manufacturing costs (for example as molded components, made for
example from suitable plastic materials), and for ease in assembly,
disassembly and replacement of sections.
[0072] In an alternative variation of this embodiment, the piston
arrangement 150 is replaced with a reciprocating piston which is
slidingly sealed with respect to cylindrical wall 155 via sliding
seal, for example piston rings or the like, and thus does not
comprise a convolution diaphragm. Otherwise, such a pump apparatus
is in all other respects substantially similar to the embodiment
illustrated in FIG. 1, and may provide similar performance though
at reduced efficiency with respect thereto.
[0073] Pump 100 is connected to exhalation valve assembly 200 via
hose 50, which is configured for coupling the outlet port 17 to
delivery tube 40 of the exhalation valve assembly 200, and which in
practice may be relatively long so as to distance the pump 100 from
the patient.
[0074] Exhalation valve assembly 200 comprises exhalation valve 700
and control valve assembly 500 for controlling the operation of the
exhalation valve 700 in order to permit inspiration and exhalation
by the patient. Control valve assembly 500 comprises a solenoid
pump unit 300 and a two-way control valve 400.
[0075] The exhalation valve 700 includes delivery tube 40, which
has an essentially T-shaped construction, having an inlet port 41,
outlet port 28; exhalation valve discharge port 25 leading to the
atmosphere; and a valve member 26 for selectively permitting fluid
communication between the outlet port 28 and the exhalation port
25. The valve inlet port 41 is configured for being coupled to hose
50 and thereby to pump 100. Exhalation valve outlet port 28 is
configured for connection to the patient being respirated, and
delivers air (or other gas, for example oxygen or oxygen enriched
air) pumped by the pump 100 to the patient via a suitable
interface, such as a patient air delivery hose, or a mask or
cannula (not shown), for example. Valve member 26 is in the form of
a diaphragm 29 seatable on a valve seat 27 and controlled by the
differential pressure between that at the inlet port 41 on one side
of the diaphragm, and a control chamber 55 on the opposite side of
the diaphragm 29. Control chamber 55 is connected by a tube 56 to
the solenoid pump unit 300, such that the operation of the control
valve assembly 500 controls the pressure within chamber 55, and
thereby the operation of valve member 26.
[0076] Solenoid pump unit 300 comprises a valve housing 33, which
includes a solenoid comprising a coil 32, and control member 30,
which comprises an armature or clapper 39 aligned with the coil 32.
The control member 30 further comprises a resilient diaphragm 31
peripherally attached to the armature 39 and to a seat 48 on the
housing 33, to define a valve chamber 34 of variable volume between
the control member 30 and the housing seat 48. The diaphragm 31 has
a generally concave form with respect to chamber 34, and a
resilience, such that the diaphragm 31 biases the armature 39 in a
direction away from the seat 48, but may nevertheless allow
movement of the armature 39 towards seat 48 when the solenoid pump
unit 300 is actuated. In this embodiment, the solenoid pump unit
300 is configured for preventing abutting contact between the
control member 30 and the housing seat 48 when the solenoid coil 32
is energized, and thus allowing for quick release when the coil is
de-energized. This is accomplished by controlling the power to the
solenoid coil 32 so as to generate sufficient magnetic attraction
to only partially overcome the bias provided by the diaphragm 31,
such that the control member 30 is closer to the housing seat 48,
but still spaced therefrom. In this embodiment, the diaphragm 31
also extends below the armature 39 preventing contact between the
armature 39 and the housing seat 48. Solenoid pump unit 300 further
comprises an inlet port 61 connected via first passageway 62 to
control port 35, which is connected via tube 56 to control chamber
55 of the exhalation valve 700. A second passageway 63 connects
valve chamber 34 with the first passageway 62.
[0077] Two-way control valve 400 may comprise any suitable 2-way
controllable valve capable of being selectively opened and closed,
and in this embodiment has a construction similar to that of the
solenoid pump unit 300, mutatis mutandis, comprising a valve
housing 73 (including seat 78), a solenoid comprising a coil 72,
control member 70 (comprising armature 36 and resilient diaphragm),
a valve chamber 74, similar to the components disclosed for the
solenoid pump unit 300, mutatis mutandis. However, in the two-way
control valve 400, the armature 36 comprises an aperture 38, which
provides fluid communication between the atmosphere and the valve
chamber 74 when the armature 38 is spaced from the housing seat 78,
but which is closed when the armature 38 is in abutting contact
with the housing seat 78; and furthermore, the two-way control
valve 400 comprises a passageway 77 that connects valve chamber 74
with an outlet port 66.
[0078] A conduit 49 connects the outlet port 66 with the inlet port
61.
[0079] In operation of the system 600, the exhalation valve
assembly 200 operates in two modes: inhalation mode and exhalation
mode.
[0080] In inhalation mode, and referring to FIG. 1 in particular,
the control valve assembly 500 is controlled to provide rapid
closing of valve member 26 with respect to valve seat 27, thereby
ensuring that air (or other gas) pumped by pump 100 is
uninterruptedly provided to the patient via delivery tube 40. To do
so, a suitable control unit (not shown) controls operation of the
control valve assembly 500 as follows. First, regarding control
valve 400, the solenoid 72 is selectively electrically energized
and the armature 36 is attracted magnetically towards the housing
seat 78, according to the magnetic force generated by the current
passing through coil 72. This results in the control member 70
being seated in abutting contact on seat 78, sealingly closing the
aperture 38. Then, and regarding solenoid pump unit 300, the
solenoid 32 is selectively electrically energized and the armature
39 is attracted magnetically towards the housing seat 48, according
to the magnetic force generated by the current passing through coil
32. This results in the air trapped in chamber 34 and in air
passages 75 of the control valve system 500 (the air passages 75
including passages 62, 63 and 77, conduit 56 and control chamber
55), being pressurized, increasing the pressure in the control
chamber 55 to higher than that at the inlet port 41, and thus
causing the valve member 26 to close. Thus, the control member 30
operates essentially as a pump, providing a pressure stroke that
pressurizes the control chamber 55 and closes the valve member 26.
It is alternatively possible to actuate both coils 32 and 72
simultaneously if two-way control valve 400 is configured for
closing much faster than solenoid pump unit 300 is able to
operate.
[0081] It is to be noted that since the two-way control valve 400
is closed first, the pressure of the air trapped within the air
passages 75 will be at ambient atmospheric pressure, and thus
subsequent operation of the solenoid pump unit 300 will pressurize
these air passages to a pressure above ambient, starting the
pressurization at nominally ambient atmospheric pressure.
[0082] In exhalation mode, and referring to FIG. 2, both coils 32
and 72 are de-energized, and the resilience of the respective
diaphragms 31 and 71 respectively return the respective armatures
39 and 36 to their inactive positions, spaced away from the
respective housing seats 48 and 78. Accordingly, the aperture 38
depressurizes the air passages 75 by venting the same to the
atmosphere, and valve member 26 is then unseated by virtue of the
higher pressure of the exhalation air delivered to the delivery
tube 40 from the patient, permitting the patient to exhale via
outlet port 28 and exhalation port 25 leading to the
atmosphere.
[0083] At least some embodiments of the present invention are
characterized by providing safety enhancement features for the
exhalation valve assembly. For example, in the embodiment
illustrated in FIGS. 1 and 2, the control valve assembly 500
comprises two actuable components, solenoid pump unit 300 and
two-way control valve 400, which are linked in series to
interconnect the valve chamber 74, valve chamber 34 and control
member 55 via passages 62, 63 and conduits 49, 56. During normal
operation of the control valve assembly 500 both components are
de-energized, and thus opened, in the exhalation mode. However, the
construction of the control valve assembly 500 is such that even if
one of the components has a malfunction and fails to open, having
the other component in the open position will nevertheless ensure
that the pressure in control chamber 55 will return to ambient
atmospheric pressure, and thereby permit the patient to exhale. For
example, if control valve 400 is opened while solenoid pump unit
300 remains closed, the control member 55 is directly vented to the
atmosphere via conduit 56, passage 62, conduit 49, passage 77,
valve chamber 74 and aperture 38. On the other hand, if solenoid
pump unit 300 is opened while control valve 400 remains closed, the
control member 55 is effectively depressurized to atmospheric, as
the volume in the valve chamber 34 is increased and conditions in
air passages 75 revert to those that prevailed prior to actuation
of the solenoid pump unit 300 during the previous inhalation mode,
i.e., at ambient atmospheric pressure, which also results in the
valve member 26 being opened as the pressure in the control member
55 is again at atmospheric. Thus, this arrangement provides a high
degree of safety and avoids a potentially hazardous situation with
respect to the patient which could otherwise result if the valve
member 29 remained closed during exhalation. Failure of both
components 300 and 400 is statistically a much rarer event than
failure of a single control valve, and the resulting redundancy can
increase the reliability of the control valve assembly 500 by
several fold.
[0084] In alternative variations of this embodiment, the aforesaid
safety feature of the exhalation valve assembly may be omitted, and
thus the exhalation valve assembly comprises only one component,
similar to solenoid pump unit 300, but without the passage 62 and
is thus not ventable thereby to atmosphere, and thus passage 63
provides fluid communication between the pump chamber 34 and outlet
35, and via conduit 56, to the control chamber 55. Operation of
such an embodiment is based on closing the solenoid pump unit
during inhalation mode to pressurize the control chamber 55, and
opening the control valve during exhalation to unseat the valve
member 26 from the seat 27. Such an arrangement may function in a
satisfactory manner, with the possible exception of the case where
there is a leak with respect to passage 63, for example in tube 56
or diaphragms 31 or valve member 26, wherein each time the valve
opens the leakage is offset/restored by flow from the
atmosphere.
[0085] At least some embodiments of the present invention are
further characterized by constructional layout of the control valve
assembly 500. For example, in the embodiment illustrated in FIGS. 1
and 2, each one of control valve 300 and control valve 400
comprises a respective control member 30, 70, having a construction
including a respective armature 36, 39 that is mounted to the
respective housing seat 48, 78 by means of a respective flexible,
resilient diaphragm 31, 71. The diaphragms 31, 71, allow for
substantially friction-free, floating movement of the respective
armature 36, 39 with respect to the respective housing seat 48, 78,
or at least with much reduced frictional forces as compared with
other types of construction, allowing for accurate control of the
pressure induced in the air passages 75 by the actuation of the
solenoid pump unit 300, without hysteresis, or at least minimizing
hysteresis as compared with other types of construction. This
construction thus provides a control valve arrangement that
produces as essentially hysteresis-free control of the exhalation
valve assembly 200.
[0086] Operation of the system 600 is as follows. During patient
inhalation, the exhalation valve assembly 200 is operated in
inhalation mode, as described above, and the pump 100 generates and
provides pressurized air to the patient, as described above, via
the outlet port 28 of the exhalation valve assembly 200. During
patient exhalation, the exhalation valve assembly 200 is operated
in exhalation mode, as described above, and the pump 100 is
stopped. Alternatively, the pump 100 may be set to operate
continuously, even during the exhalation mode, such that while most
of the pressurized air generated by the pump is discharged via
exhalation port 25 during exhalation mode, a low pressure is still
maintained in the patient's lungs (commonly referred to as
"positive end exhalation pressure" or PEEP). A suitable controller
(not shown) controls operation of the pump 100 and of the
exhalation valve assembly 200 and synchronizes operation between
the two.
[0087] In alternative embodiments of the invention, the pump 100
may alternatively be used with other types of exhalation valves
known per se in the art, and the resulting system controlled in a
suitable manner for enabling inhalation and exhalation of the
patient.
[0088] In alternative embodiments of the invention, the exhalation
valve assembly 200 may alternatively be used with other types of
pumps known per se in the art, and the resulting system controlled
in a suitable manner for enabling inhalation and exhalation of the
patient.
[0089] Finally, it should be noted that the word "comprising" as
used throughout the appended claims is to be interpreted to mean
"including but not limited to".
[0090] While there has been shown and disclosed example embodiments
in accordance with the invention, it will be appreciated that many
changes may be made therein without departing from the spirit of
the invention.
* * * * *