Note: Descriptions are shown in the official language in which they were submitted.
36~4~3
1.
IMPROVED EXHALATION VALVE ASSEMBLY
3ACKGROUND OF ~HE INVENTION
1. Field of the Inventiorl.
This invention relates to respiratory therapy
S devices and, more particularly, to the design and
construction of an improved exhalation valve asse~bly
that can be used in various volume ventilator circuits.
2. Descri~tion o~ the Prior Art.
An example of a prior art exhalation valve
assembly is disclosed in United States Patent No.
4,241,756. As noted in that patent, volume ventilator
circuits utilize an exhalation valve assembly to hold
and maintain pressure within the circuit and
selectively allow gases to be exhaled by the patien~
lS and to escape therefrom. Exhalation valve assemblies
are comprised of a valve body having a gas inlet
conduit, which forms a gas discharge port within the
valve body, and a gas outlet conduit. A ~lexible
diaphragm selectively closes of the discharge port
during inhalation. When the patient exhales, the
diaphragm is pushed away from the port so as to allow
the exhaled gases to escape from the valve body through
the gas outlet conduit.
Volume ventilators, in general, have diferent
pressure holding capabilities dependin~ on their
particular application. One determinant of pressure
holding capability is the ratio of the area of the
diaphragm that extends across the chamber of the valve
body (hereinafter referred to as "effective area~) to
the area of the gas discharge port. This ratio will
hereinafter be referred to as the ~valve area ratio."
One of the most widely used volume ventilators in
the respiratory therapy field has a limited capability
for holding elevated Positive End Expiration Pressure
("P.E.E.P.~) when using a circuit with a valve assembly
having a valve area ratio usually below l.S. The valve
assembly used ir- such a circuit i9 specifically
- . . . .
~ 3~Y~
designed to achieve a particular ratio and cannot be
modified so as to be used in another circuit requiring
a different ratio. Another popular volume ventilator
is not dependent upon the valve area ratio for high
S P.E.E.P. pressures, but rather is dependent on the
valve area ratio for low patient exhalation effort
beyond P.E.E.P. preqsures. The valve assembly is
specifically designed to achieve the required valve
area ratio and cannot be modified to provide a
different ratio for use in a different machine. Thus,
prior art volume ventilators have required the use of
specifically designed valve assemblies in order to
achieve the desired valve area ratio. Notwithstanding
the increased costs of manufacturing one specific valve
for one type of machine, the prior art has been unable
to provide any interchangeability of such valve
assemblies.
The prior art valve assembly disclosed in the
previously mentioned patent provided a means of using
the same exhalation valve assembly in volume ventilator
circuits requiring different valve area ratios. This
was accomplished by a removable ring member r which
supported a portion of the diaphragm being used.
While this construction allowed great flexibility,
it was often not fully utilized. That is, this prior
art valve a~sembly was often not used without the ring
member even though it could have been so used. In
practice, the configuration most often used was to
leave the ring member in place and use diaphragms of
varying con3truction and material, thereby changing the
pressure holding capability of the volume ventilator
and the effective area of the diaphragm. This meant
unnecessary complexity and unnecessarily greater
manufacturing and parts costs. The present invention
overcomes these problem~ by providing a valve assembly
that provides for diferent preC~ure holding
capabllities while eliminating the need for support
members and for the removable ring member.
.
~I ~f`~ 34
3.
SUMMARY OF THE INVENTION
Accordingly the present invention seeks to provide
an exhalation valve assembly that can be used in
diEferent volume ventilator circuits while
incorporating a more simple construction than previous
valve assemblies.
The exhalation valve assembly of the present
invention is designed for use in gas flow circuitry
such as a volume ventilator circuit. The valve
assembly includes a valve body having a chamber ln flow
communication with the gas inlet conduit ~nd the gas
outlet conduit. The gas inlet conduit is configured to
be coupled to a patient such that exhaled gases from
the patient are directed through a gas discharge port
into the chamber formed in the valve body. The gas
outlet conduit directs the exhaled gas out of the
chamber.
A diaphragm extends across the chamber formed in
the valve body and is configured to selectively close
off the discharge port. The diaphragm is held in
position by a removable cap that permits easy
replacement of the diaphragm with diaphragms of
different configuration and construction. The cap
includes a gas inlet port for introducing a gas into
the area between the diaphragm and the cap.
In order to support the diaphragm, the prior art
valve assembly used a plurality of upwardly extending
strut members disposed around the chamber on the
internal wall of the valve body, as well as using a
portion of the valve body itself to support the
diaphragm along its periphery. The strut members were
used to support a removable ring member which supported
a portion of the diaphragm rom extending across the
chamber, thereby reducing the effective area o the
diaphragm. The present invention eliminates the strut
members and removable ring member. Instead, the
present invention incorporates a concentric wall
r~
34~
4.
di~posed around the cha~ber^a predetermined distance
from the internal wall o~ the valve body. Depending on
the particular diaphragm being used, the concentric
wall or ring structure will come in contact with a
portion of the diaphragm and thereby reduce the
effective area of the diaphragm.
Use of the ring structure allows Eor the
elimination of the upwardly extending support members
and the associated removable ring member, re~ulting in
reduced manufacturing costs and fewer parts. Further,
there is no removable ring member that may be misplaced
and the valve assembly is easier to use, since it is no
longer necessary to train someone in utilizing the
various combinations of ring member and diaphrag~
construction.
The concentric ring structure serves the same
purpose as the upwardly extending support structure
members and removabl~ ring member, but improves upon
the prior design. More specifically, during
inhalation, the diaphragm closes off the discharge
port, as before. Upon exhalation, the diaphragm is
likewise disengaged from the discharge port. ~owever,
depending on the diaphragm used and the pressure
created by introducing a gas through the inlet port of
the cap, exhaled air may pass out of the chamber and
into the outlet conduit on only one side of the ring
structure or on both sides. Thus, in order to change
the pressure holding capability of a volume ventilator
circuit utilizing the present invention, one need
merely remove the cap from the valve a sembly, remove
and replace the diaphragm, and replace the capO
The novel features that are believed to be
characteristic of the present invention, both as to its
organization and method of operation, together with
further objectives and advantage~ thereof~ will be
better understood from the following description
considered in connection with the acGompanying drawings
34~
s.
in which a presently preferred embodiment of the
invention is illustrated by way of example. It is to be
expressly understood, however, that the drawin~s are for
the purpose of illustration and description only and are
not intended as a definition of the limits of the
invention.
Although other aspects of the invention will
become evident herein, the invention in one claimed
aspect pertains to a valve assembly for use in a volume
ventilator, the valve assembly comprising a valve body
having an exterior wall in part defining a pressure
chamber, a gas inlet conduit in flow communication with
the pressure chamber, the gas inlet conduit forming a
circular discharge port in the pressure chamber, and a
circular gas outlet conduit concentric with and around
the discharge port and in flow communication with the
pressure chamber for directing gas out of the pressure
chamber. Diaphragm means is removably disposed in and
extends across the valve body, the discharge port, the
outlet conduit and the pressure chamber being on one
side of the diaphragm means. The diaphragm means
includes a circular center portion ~or selectively
engaging and closing off the discharge port. The
diaphragm means has a circular shape and rests along its
circumference on the exterior wall of the valve body and
has an annular arcuate arched section concentrically
disposed between the center portion and the
circumference, the diaphragm means defining the
remainder of the pressure chamber. A cover has a gas
inlet joined to the valve body and extends across the
diaphragm means on the opposite side thereof from the
pressure chamber, the cover clamping the circumference
of the diaphragm. A generally tubular ring structure is
35 disposed within the pressure chamber, the ring structure
being integrally formed on the valve body and disposed
6.
concentrically about and adjacent to the discharge port
and separated from the exterior wall by a predetermined
dis-tance and thereby forming a flow passage between the
ring structure and the exterlor waLl and forming a flow
passage between the discharge port and the ring
structure. The flow passage communicates with the
discharge port, the ring struc-ture being spaced in the
direction of -the opposite side from the discharge port
and from the circumference of the diaphragm means. The
ring structure is engageable wi-th and adapted to support
the arched section of the diaphragm means when the
diaphragm means is in its relaxed position.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is an exploded perspective view of
the prior art exhalation valve assembly;
Figure la is a cross section of the prior art
exhalation valve assembly;
Figure 2 is an exploded perspective view of
the exhalation valve assembly of the present invention;
Figures 2a, 2b and 2c are cross sections of
the exhalation valve assembly of the present invention.
~ .
~ ~36~
7.
DETAILED DESCRIPTION OF THE-INVENTION
Referring to Figure 1 and Figure la, the valve
assembly 10 of one prior art valve assembly is shown.
This prior art ~alve assembly 10 is comprised of a
valve body 12 formin~ a generally circular housing 14
defining I chamber 16. An inlet conduit 18 and an
outlet conduit 20 are in flow communication with
chamber 16. One end of the in]Let conduit 18 includes a
section 26 which extends into t:he chamber 16 and forms
a circular gas discharge port 24. Disposed on the
inside wall of the valve body 12 are a plurality of
upwardly extending support members or struts 28. Such
support members 28 are used to position a ring member
38 inside the housing 14. Also disposed on the valve
body 12, adjacent the bottom thereof, is an outwardly
extending and generally rectangular mounting support
member 22. Such mounting support member 22 enables the
valve assembly 10 to be attached to a support structure
(not shown) and thereby held in a predetermined
position.
The valve assembly 10 also includes a flexible,
circular diaphragm member 32 that is disposed across
the chamber 16. A cap or cover 34 snap locks onto the
body 12 and holds the diaphragm 32 across the chamber
16. Centrally located on the cover 34 is a gas inlet
port 36 that can be used to direct a gas into the
assembly 10. The gas, however, does not flow into the
chamber 16 but i8 directed into the area above
diaphragm 32.
A circular plastic ring member 38 is disposed in
the valve body 12 and rests on the support members 2a.
The ring member 38 is di posed adjacent the periphery
of chamber 16 and circumferentially surrounds the gas
discharge port 24. Once the ring member 38 is in
position, the diaphragm 32 is placed over it. The
diaphragm 32 includes an upwardly extending section 54
configured to arch over the ring member 38 and includes
~ 9'~
a generally circular sectio~ S6 that is used to
selectively close-off the gas discharge port 24. The
diaphragm 32 rests on a groove area 46 ormed by an
inner wall 42 and an outer wall 44 on the valve body
12. When the cover 34 is disposed over the diaphragm
32, it snap locks over lip 40.
The ring member 38 supports a portion of the
diaphragm 32, thereby occluding such portion of the
diaphragm 32 from extending across the chamber 16. In
this way, the effective area of the diaphragm 32 over
the chamber 16 is decreased, thereby decreasing the
valve area ratio. ~ecause of this, less pressure is
required to raise the diaphragm 32 off of the gas
discharge port 24.
Referring now to Figure 2 and Figure 2a, the valve
assembly 100 of the present invention i5 shown. The
valve asssmbly 100 is comprised o~ a valve body 112
forming a generally circular housing 114 defininy a
chamber 116. An inlet conduit 118 and an outlet
conduit 120 are in flow communication with chamber 116.
One end of the inlet conduit 118 includes a section 126
that extends into the chamber 116 and forms a circular
gas discharge port 124. In the preferred embodiment,
port 124 ic~ circumferentially disposed in chamber 116.
Located concentrically about and generally parallel to
the walls of the discharge port 124 in the chamber 116
is a concentric tubular ring structure 128 integrally
formed on valve body 112. Wall section 142 and wall
section 144 are also integrally formed on the valve
body 112 concentrically with the gas discharge port
124, but are not located within the chamber 116. Wall
sections 142 and 144 define the exterior wall of the
valve body 1120 Thus, in effect, there are three
concentric, generally parallel wall structures located
about the discharge port 124; that is, moving out from
discharge port 124 is the ring 128, the inner wall
section 142, and the outer wall section 144. In the
i9f~
9.
preferred embodiment, ring 128 extends above the top of
wall sections 142 and 144.
The valve assembly 100 includes a circular,
flexible diaphragm 132 that is disposed across the
s chambec 116. An outwardly extending annular seat 155
is disposed about the circum~erence of the diaphragm
132. The annular seat 155 rests in a grooved area 146
formed by the inner wall 142 and the outer wall 144. A
cap or cover 134 snap locks onto the body 112 and holds
the diaphragm 132 acroc~s the chamber 116. Centrally
located on the cover 134 is a gas inlet port 136 that
can be used to direct a gas into the assembly 100. As
with the prior art assembly, the gas is not directed
into the chamber 116 but is directed into the area
above diaphragm 132.
The diaphragm 132 includes an upwardly extending
section 154 that, in certain embodiments of the
diaphragm, is designed to arch over the ring structure
128. A generally circular section 156 of the diaphragm
is used to selectively close-off the gas discharge port
124. The concentric ring structure 128 takes the place
of the support members 28 and ring member 38 previously
described in Figure 1 and discussed in the description
of the prior art.
A wide variety of materials, shapes, and other
configurations can be used in this invention. For
example, in the preferred embodiment all of the parts
of the present invention are ma~e of a plastic material
such as nylon, PVC, acrylic re3ins, and the like. Of
course, other materials such as reinforced plastics or
even metal are within the scope of the present
invention. Further, the shape of the diaphragm and
materials used to construct it can be modified so as to
achieve variouc; valve area ratio~ and pressure holding
capabilities. This invention, therefore, is not to be
limited to the specific embodiments discussed and
illustrated herein.
9~
- 10.
Operation of the prior art valve assembly 10 and
valve assembly 100 of the present invention will now be
discussed. In one manner of operation, a patient
connection hose (not shown) is ~ecured to the gas inlet
conduit 18. Likewise, an outlet hose (not shown) is
secured to the gas outlet conduit 20. During
inspiration, it is necessary to maintain a positive
pressure above diaphragm 32. Therefore, a ga~ supply
; tube (not shown) is joined to the gas inlet port 36 on
the cover 34 such that a gas is directed into the
assembly 10 above the diaphragm 32, thereby enabling a
positive pressure to be created above the diaphragm.
During exhalation, it is sometimes desirable to
maintain a positive pressure above the diaphragm 32,
thus forcing the patient to exert an increased pressure
in order to exhale through the valve assembly. The
amount of increased pressure exerted is de~ermined by
the air pressure applied above the diaphragm and by the
valve area ratio.
The operating principle of the valve assembly 100
o the present invention is similar to that of the
prior art assembly. A patient connection hose is
secured to the gas inlet conduit 118 and an outlet hose
is secured to the gas outlet conduit 120. During
inspiration, a positive pressure is maintained above
diaphragm 132, and a gas supply tube (not shown~ is
joined to the gas inlet port 136 for this purpose. The
gas is directed into the assembly 100 above the
diaphragm 132, thereby enabling a positive pressure to
be created above the diaphragm. Again, it is sometimes
desirable to maintain a positive pressure above the
diaphragm during exhalation, thus forcing the patient
to exert an increased pressure in order to exhale
through the valve assembly. Likewise, the air pressure
applied above the diaphragm and the valve area ratio of
i the present invention determine the increased pressure
exerted. It is to be understood, however, that in
'' ; ' ',, ' '. . .
~ 3'~
other applications of the prior art assembly and of the
present invention, it may be desirable not to maintain
such positive pressure. In such cases, no pressure
would be maintained above the respective diaphragms
during exhalation.
Figures la and 2a include arrows 70 which
generally indicate the flow of gas exhaled from a
patient as it would be directed through an embodiment
of the respective valve assemblies. More specifically,
when the patient exhales with sufficient pressure, the
pressure above the respective diaphragms 32, 132 is
overcome. This causes the diaphragms 32, 132 to
disengage the ports 24, 124. The exhaled gas then
flows through the inlet conduit 18, 118l through gas
discharge ports 24, 124, and then into the chambers 16,
116. The exhaled gas would flow out of the chambers
16, 116 through the outlet conduit 20, 120. ~s
indicated by Figure 2a, the exhaled gas may flow on
both sides of the ring structure 128. Depending on the
diaphragm employed, the diaphragm may maintain contact
with the ring structure 128 during exhalation,
decreasing the effective area of the diaphgram. During
inspiration, a positive pressure is created in the
respective assemblies 10, 100 above diaphragms 32, 132
causing sections 56, 156 of the diaphtagm~ 32, 132 ~o
engage discharge ports 24, 124. This prevents gas rom
escaping from the patient circuit through the valve
assembly. Air or other gas to the patient comes from
the ventalator, which is connected to the patient
circuit upstream from the valve assembly.
In the prior art valve assembly, the ring member
38 extended toward the center of the chamber 16 and in
one embodiment supported a portion of the diaphragm 32.
By acting as a support for a section of the diaphragm
32, the ring member 38 decreased the amount of force
necessary to disengage the diaphragm 32 from the
discharge port 24. If one desired to increase the
12.
force necessary to disengage the diaphragm 32 from the
port 2~, the ring member 38 could be removed and/or a
different diaphragm or ring could be used. In the
present invention, one may chancle the amount of force
necessary to disengage the diaphragm 132 from the
discharged port 124 by changing the configuration
and/or the compositlon of the diaphragm 132. In this
way, a diaphragm may be used that is partially
supported by the ring member 12~1. Of course, one may
also change the amount o~ force needed by changing the
pressure of the gas directed above the diaphragm 132
via the gas inlet port 136. In this way, it is
possible to achieve the benefits of the prior art valve
assembly ~achieving various valve area ratios utilizing
the same valve assembly) without the need for a
removable ring member.
