U.S. patent number 3,730,180 [Application Number 05/082,755] was granted by the patent office on 1973-05-01 for pneumatically operated ventilator.
This patent grant is currently assigned to Mine Safety Appliances Company. Invention is credited to Ellison L. Davison.
United States Patent |
3,730,180 |
Davison |
May 1, 1973 |
PNEUMATICALLY OPERATED VENTILATOR
Abstract
A pneumatically operated pump is connected with a conduit for
supplying a gas to a patient's lungs. A first fluidic control
element and a pneumatic timer control means for delivering air
under pressure to the pump for operating it. The fluidic control
element is controlled by a second fluidic control element, which in
turn is controlled by a third fluidic control element. The latter
is controlled by the movement of the pump during lung inflation to
reverse the pump in order to allow exhalation. The second control
element also controls an exhalation valve. Other elements provide
for periodic longer inhalation periods, excess pressure release and
sudden inhalation.
Inventors: |
Davison; Ellison L. (Gibsonia,
PA) |
Assignee: |
Mine Safety Appliances Company
(Pittsburgh, PA)
|
Family
ID: |
22173238 |
Appl.
No.: |
05/082,755 |
Filed: |
October 21, 1970 |
Current U.S.
Class: |
128/204.24;
137/819 |
Current CPC
Class: |
A61M
16/00 (20130101); A61M 16/0012 (20140204); A61M
16/107 (20140204); A61M 16/0075 (20130101); Y10T
137/2147 (20150401) |
Current International
Class: |
A61M
16/00 (20060101); A61m 016/00 () |
Field of
Search: |
;128/145.6,145.8,188,145.5,145.7,142,142.2 ;137/81.5 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Gaudet; Richard A.
Assistant Examiner: Dunne; G. F.
Claims
I claim:
1. A ventilator comprising a conduit for supplying a gas to a
patient's s lungs, a pneumatically operated pump having a rapid
suction stroke and a pressure stroke for alternately drawing in a
charge of a gas and then forcing it out through said conduit, means
for delivering air under pressure to the pump for operating it,
pneumatically operated control means shiftable back and forth
between two positions for controlling said delivery of air, means
restricting flow of said air from said control means in only one Of
said positions to admit operating air to the pump slowly to produce
a slow pressure stroke, means for supplying control air to said
control means for the shifting thereof, a first fluidic control
element controlling the supply of control air to said control
means, a pneumatically operated timer, a second fluidic control
element having an outlet for delivering control air to the first
fluidic control element to cause it to shift said control means to
connect said air delivering means with the pump to produce the
rapid suction stroke of the pump, a first air line for also
delivering air from said outlet to the timer to start it operating,
a second air line adapted to be opened by the timer when the timer
times out, said second air line being connected to the first
fluidic control element to cause said first element to shift said
control means to connect said air delivering means with the pump to
produce the slow pressure stroke of the pump, a normally
inoperative third fluidic control element having a power outlet,
means controlled by the movement of the pump at the end of its
pressure stroke for rendering the third fluidic control element
operative, a third air line for delivering control air from said
power outlet to said second fluidic control element to cause air to
issue from said outlet of said second element, an exhalation valve
connected with said conduit and having a closed position and an
open position and normally being in one of said positions, means
operatively connecting said second fluidic control element with
said valve for shifting the valve to its other position, a venturi
in series with the exhalation valve and having an inlet for
communication with the patient's lungs, the venturi being provided
with a power jet, a normally closed valve connected with said jet,
means for supplYing air under pressure to the jet when said
normally closed valve is opened to thereby withdraw gas from a
patient's lungs, and a fluidic control element controlled by said
second control element for opening said normally closed valve while
the exhalation valve is open.
2. A ventilator comprising a conduit for supplying a gas to a
patient's lungs, a pneumatically operated pump having a rapid
suction stroke and a pressure stroke for alternately drawing in a
charge of a gas and then forcing it out through said conduit, means
for delivering air under pressure to the pump for operating it,
pneumatically operated control means shiftable back and forth
between two positions for controlling said delivery of air, means
restricting flow of said air from said control means in only one of
said positions to admit operating air to the pump slowly to produce
a slow pressure stroke, means for supplying control air to said
control means for the shifting thereof, a first fluidic control
element controlling the supply of control air to said control
means, a pneumatically operated timer, a second fluidic control
element having an outlet for delivering control air to the first
fluidic control element to cause it to shift said control means to
connect said air delivering means with the pump to produce the
rapid suction stroke of the pump, a first air line for also
delivering air from said outlet to the timer to start it operating,
a second air line adapted to be opened by the timer when the timer
times out, said second air line being connected to the first
fluidic control element to cause said first element to shift said
control means to connect said air delivering means with the pump to
produce the slow pressure stroke of the pump, a normally
inoperative third fluidic control element having a power outlet,
means controlled by the movement of the pump at the end of its
pressure stroke for rendering the third fluidic control element
operative, a third air line for delivering control air from said
power outlet to said second fluidic control element to cause air to
issue from said outlet of said second element, a second pneumatic
timer for periodically lengthening said pressure stroke to expel a
larger charge of gas than normally, means controlled by the
movement of the pump at the end of its pressure stroke during lung
inflation for resetting the second timer, a conduit connecting said
third fluidic control element to the second timer and normally
closed by the second timer, the second timer periodically opening
said last-mentioned conduit to render said third control element
inoperative.
3. A ventilator comprising a conduit for supplying a gas to a
patient's lungs, a pump having an outlet connected with the conduit
and having a fluid pressure cylinder and a piston movable back and
forth therein for alternately drawing gas into the pump and forcing
it out through said conduit, pneumatically operated valves
connected with the opposite ends of the cylinder, means for
supplying operating air under pressure through said valves to the
cylinder, means for supplying control air to said valves for
operating them, means restricting flow of operating air from one of
said valves in one position to one end of the cylinder to cause the
pump to force gas out through said conduit, said valves in another
position by-passing said restricting means to admit operating air
to the other end of the cylinder rapidly to cause the pump to draw
in gas, a first bistable fluid amplifier controlling the control
air supply to said valves, a pneumatically operated timer, a second
bistable fluid amplifier having an outlet for delivering control
air to said first fluid amplifier to cause it to operate the valves
to connect said air supplying means to said other end of the
cylinder,a first air line for delivering air from said outlet to
the timer to start it operating, a second air line adapted to be
opened by the timer when the timer times out, said second air line
being connected to the first fluid amplifier to cause said first
fluid amplifier to operate said valves to connect said air
supplying means to said one end of the cylinder, a normally
inoperative third fluid amplifier having a power outlet, means
controlled by the movement of said piston during lung inflation for
rendering the third fluid amplifier operative, and a third air line
for delivering control air from said power outlet to said second
fluid amplifier to cause air to issue from said outlet of said
second fluid amplifier, said third fluid amplifier being a
monostable element having an inlet passage, a normal outlet
passage, a control passage for shifting a stream of air from the
normal outlet to said power outlet, and a by-pass connecting said
inlet passage to the control passage for normally directing a
stream of air through the control passage away from said fluid
amplifier, and said piston-controlled means including means for
blocking said stream from the control passage to cause it to effect
said stream shift.
4. A ventilator comprising a conduit for supplying a gas to a
patient's lungs, a pump having an outlet connected with the conduit
and having a fluid pressure cylinder and a piston movable back and
forth therein for alternately drawing gas into the pump and forcing
it out through said conduit, pneumatically operated valves
connected with the opPosite ends of the cylinder, means for
supplying operating air under pressure through said valves to the
cylinder, means for supplying control air to said valves for
operating them, means restricting flow of operating air from one of
said valves in one position to one end of the cylinder to cause the
pump to force gas out through said conduit, said valves in another
position by-passing said restricting means to admit operating air
to the other end of the cylinder rapidly to cause the pump to draw
in gas, a first bistable fluid amplifier controlling the control
air supply to said valves, a pneumatically operated timer, a second
bistable fluid amplifier having an outlet for delivering control
air to said first fluid amplifier to cause it to operate the valves
to connect said air supplying means to said other end of the
cylinder, a first air line for delivering air from said outlet to
the tImer to start when the timer times out, said second air line
being connected to the first fluid amplifier to cause said first
fluid amplifier to operate said valves to connect said air
supplying means to said one end of the cylinder, a normally
inoperative third Fluid amplifier having a power outlet, means
controlled by the movement of said piston during lung inflation for
rendering the third fluid amplifier operative, and a third air line
for delivering control air from said power outlet to said second
fluid amplifier to cause air to issue from said outlet of said
second fluid amplifier.
5. A ventilator according to claim 4, including a pneumatically
operated normally open exhalation valve connected With said
conduit, said second fluid amplifier having a second outlet, and
said second air line also delivering control air from the timer to
said second fluid amplifier to cause it to deliver air from its
second outlet to the exhalation valve to close it.
6. A ventilator according tO claim 4, including an exhalation valve
connected with said cOnduit having a closed position and an open
position, the valve normally being in one of said positions, and
said second fluid amplifier being operatively connected with the
valve for shifting it to its other position.
7. A ventIlator according to claim 4, including normally inactive
means responsive to excessive gas pressure in a patient's lungs
while the pump is forcing gas through saId conduit for reversing
said first fluid amplifier, whereby to start the pump drawing in
gas.
8. A ventilator according to claim 4, including a second pneumatic
timer for periodically lengthening said pressure stroke to thereby
expel a larger charge of gas than normally, and means controlled by
the movement of the pump at the end of its pressure stroke durIng
lung inflation for resetting the second timer.
Description
For any one of several reasons, such as being heavily drugged or
having a damaged respiratory system, a person may require
assistance in breathing. Or, it may be desirable to administer an
anesthetic gas to a patient. For these purposes ventilators are
provided that pump a gas, such as air, oxygen, an anesthetic and
the like, into and out of the patient's lungs. The ventilators
generally are electrically operated, but there are situations where
electricity may not be available or where it may fail. Also, an
electrically operated ventilator may be sensitive to radiated
electrical signals, or an electric spark from it may set off an
explosion.
It is among the objects of this invention to provide a ventilator
which is completely automatic, which does not depend upon
electrical or mechanical power to operate it, which is not affected
by electrical radiations, which cannot cause an explosion if there
is an explosive atmosphere around it, which is dependable in
operation and which is constructed from a minimum of moving
parts.
The preferred embodiment of the invention is illustrated in the
accompanying drawing, which is a diagram of the entire system.
Referring to the drawing, a bellows 1, that forms part of a gas
pump, has an inlet through which air can be drawn through a filter
2 and two check valves 3 and 4. Between the check valves there is a
connection from a needle valve 5 connected with an optional oxygen
supply 6 or a tank of anesthetic gas or the like. The bellows has
an outlet connected through a check valve 7 to a conduit 8 that
extends to a mask 9 to be worn by a patient requiring ventilation.
Connected with this conduit is an exhalation conduit 10 containing
a pneumatic solenoid valve 11 and a modulating valve 12 leading to
the atmosphere. Valve 11 is an exhalation valve, preferably
normally open, and the modulating valve controls exhalation rate.
Conduit 8, between the exhalation conduit and the mask, may include
a venturi 13 that has a poWer jet 14 directed away from the mask
and connected through a needle valve 15, a way pneumatic solenoid
valve 16 and an on and off valve 17 to a source of air under
pressure. When the last-mentioned valve is opened, the venturi
helps the patient exhale by withdrawing air or other gas from his
lungs and forcing it out through the exhalation valve.
To actuate the pump, which will be described as if in a vertical
position, the movable bottom wall of the bellows is reciprocated.
This can be done by a fluidic control element, or by a piston 20
connected to it by a rod 21. The piston is disposed in a cylinder
22 having a combined inlet and outlet near each end. The cylinder
ports are connected through three-way pneumatic solenoid valves 23
and 24 with a source 25 of air under pressure. The initial pressure
may be over 50 p.s.i., but it is reduced by a regulator 26 to a
pressure of about 20 p.s.i. The regulator may also supply the air
pressure to on and off valve 17. When the lower valve 24 is
operated to connect the air supply with the lower end of the
cylinder, the piston is raised at a rate determined by a needle
valve 27. At the same time, air above the piston escapes to the
atmosphere through the upper valve 23. When the valves are
reversed, the piston is moved down rapidly, the air below it being
exhausted to the atmosphere through the lower valve 24.
Consequently air, for example, is forced into the lungs of the
patient at a desired slow rate, but during exhalation the bellows
is expanded rapidly so that the bellows will be full of air in case
the patient requires air before the normal exhalation cycle of this
ventilator terminates, as will be explained presently.
It is a feature of this invention that all of the pneumatic valves
are actuated by pneumatic pressure controlled by fluidic control
elements, often referred to as fluid amplifiers. The air for
operating these control elements, and by which they operate the
valves, preferably comes from the main pressure source 25, but it
first passes through a second regulator 29 that reduces the
pressure to only a few pounds p.s.i. Air flows continuously down
through all of the control elements, the connection from regulator
29 to them being indicated by triangle 30 and the small triangles
at the control element inlets.
The main passage through a monostable fluidic control element 31
has a restricted by-pass 32 that connects it with the lateral
control passage 33, which in turn is connected by a line 34 with a
vertical nozzle 35 carried by an arm 36 projecting from the side of
the piston rod above the cylinder. Some of the air entering control
element 31 flows continuously from this nozzle until the piston
rises high enough for the nozzle to engage and be closed by a
vertically adjustable spring loaded plunger 37 above it. When this
occurs, the air flowing through restriction 32 exerts enough
pressure against the side of the main stream through the control
element to deflect it into the power outlet passage 38 that is
connected by a line 39 with a control passage 40 of a fluidic
control element 41. The power stream through this control therefore
is deflected into the right-hand outlet passage 42 that is
connected by a line 43 with a control passage 44 of a bistable
control element 45. This deflects the power stream through element
45 into its right-hand outlet passage 46 that is connected by a
line 47 with upper valve 23 for the pump cylinder to operate that
valve so that it will admit air pressure into the top of the
cylinder to drive the piston downwardly rapidly. At the same time,
lower valve 24 shifts to connect the lower end of the cylinder with
the atmosphere.
Air from outlet 42 of element 41 also is delivered through a line
50 to a pneumatic timer 51, through which a power stream of air
normally flows to atmosphere. The pressure of air from line 50 sets
the timer operating and after a predetermined length of time, which
is the period desired for exhalation, the timer times out and a
pulse of power stream air is delivered through a line 52 to the
right-hand control passage 53 of element 41 to shift the power
stream therein into its left-hand outlet passage 54. This stream,
flowing through a line 55, closes the normally open exhalation
valve 11. At the same time, a pulse of air from timer line 52
enters the right-hand control pAssage 56 of element 45 to shift the
main stream therein to its left-hand outlet passage 57 by that is
connected by line 58 with the lower valve 24 of the pump cylinder.
This will shift the valve to connect the main air supply with the
lower end of the cylinder so that the piston will be driven
upwardly to force air out through conduit 8 and into the lungs of
the patient. At the same time, valve 23 returns to its normal
position, in which it cOnnects the upper end of the cylinder with
the atmosphere. As soon as nozzle 35 again engages plunger 37,
valves 23 and 24 and the movement of the piston will be reversed to
repeat the cycle just explained.
It has been found that a patient being ventilated, periodically
requires an extra volume of air, which is manifested by a sigh. To
provide for this extra volume the piston arm carries a second
nozzle 60 below a vertically adjustable stop 61, the lower end of
which is located at a higher level than the lower end of the
plunger beside it. This second nozzle is connected by a line 62
with the control passage 63 of a monostable fluidic cOntrol element
64 having the same construction as control 31. Since the second
nozzle ordinarily does not rise high enough to be closed by the
stop above it, control 64 normally remains inactive and the power
stream simply flows straight through it. However, the second nozzle
does move higher periodically, which is allowed by the upwardly
movable spring-loaded plunger 37. It is accomplished by a timer 65
that has a normally closed inlet connected by a line 66 with the
line 34 between control 31 and its nozzle 35.
When control 31 is actuated to direct air out of its power outlet
passage 38, some of this air enters the right-hand control passage
67 of a bistable control element 68 to deflect the power stream
therein into the left-hand power outlet passage 69, which is
connected by a line 71 to timer 65. This sets the timer to
operating so that after a selected period of time, which may be ten
to twenty minutes, its normally closed inlet will be opened to
by-pass the air from the lateral control passage 33 of control
element 31. Consequently, the next time nozzle 35 engages the
plunger, control element 31 will not be affected because there Will
be no back pressure to cause air in passage 33 to shift the power
stream, and the piston will continue to rise until the second
nozzle 60 engages stop 61. When this occurs, the pOwer stream
through control 64 will be shifted to its outlet passage 72, which
is connected by a line 73 with the left-hand control passage 74 of
control element 68 and the flow of air through line 71 to timer 65
will be cut off so that the timer will reset to close line 66, and
control element 31 will be made operative again. Of course, while
nozzle 60 is rising the extra distance to its stop, a larger volume
of air is being forced out of the bellows and into the lungs of the
patient. Line 73 also is connected to a second inlet to control
element 41 to reverse that element.
In case the patient inhales while the piston is at the lower end of
the cylinder and waiting for timer 51 to let it move upwardly
again, provision is made for short circuiting the timer so that the
patient will be supplied with the air he desires. For this purpose
the conduit 8 to the mask is connected by a line 75 to a chamber
76, one wall of which is a flexible diaphragm 77. This diaphragm
normally closes the end of a tube 78 leading from a line 79,
through which a stream of air flows continuously into the lateral
control passage 80 of a monostable fluidic control element 81 to
normally cause the power stream of air flowing through that control
to pass into the atmosphere. However, if the patient inhales while
the bellOws is expanded and stationary, waiting for the timer to
allow it to be compressed, the air pressure in chamber 76 will be
reduced so that its diaphragm will rise and open tube 78. This will
allow air to escape from the tube so that the power stream flowing
through control element 81 will be permitted to shift back and flow
out through an outlet passage 82 connected by a line 83 with a
second right-hand control port for control element 41, whereby to
cause the power stream flowing through that element to leave
through passage 54 to close the exhalation valve. At the same time,
the stream from control 81 will also flow through a line 84 to a
right-hand side cOntrol port for control element 45 and shift the
stream therein to the left-hand outlet passage 57 so that the lower
cylinder valve 24 will be opened to admit air pressure to the
bottom of the cylinder. This piston therefOre will rise immediately
and deliver air to the patient without waiting for timer 51 to time
out.
Another feature is that if the gas pressure in the patient's lungs
starts to become excessive, It can be relieved. To do this, a line
86 connects cOnduit 75 with a second chamber 87 having flexible
diaphragm wall 88 that normally is held in a raised position by an
adjustable spring 89. Spaced a short distance from this diaphragm
is the open end of a tube 90, through which a stream of air flows
continuously. This tube iS connected by a line 91 with line 39 and
therefore with control passage 40 of control element 48. Normally,
the stream of air entering tube 90 has no effect on anything
because the tube, being open, pressure cannot be built up. However,
if the pressure in the patient's lungs starts to exceed a
predetermined value the pressure in chamber 87 will increase and
move its diaphragm down until it closes the tube. The air stream
then will be diverted through lines 91 and 39 to control element
41. This will shift the power stream in control 41 to outlet
passage 42 so that control 45 also will be shifted and the upper
cylinder valve will be opened to drive the piston down immediately.
At the same time, the exhalation valve 11 will open and relieve the
pressure in the patient's lungs.
If the assistance of venturi 13 is desired during exhalation, valve
17 is opened manually and after that the action of the venturi will
be automatic. This is because normally closed pneumatic solenoid
valve 16 is connected by a line 93 with the power outlet passage 94
of monostable fluidic control element 95 that also has an outlet 96
to atmosphere. A lateral control passage 97 is connected by a line
98 to line 43. When the system switches to the exhalation cycle and
air from control element 41 is directed into line 43, the power
stream through control element 95 is diverted into passage 94 and
line 93 to open valve 16 so that air under pressure will issue from
jet 14 of the venturi. As soon as the pressure in control passage
97 is relieved by the change to the inhalatIon cycle, valve 16
closes.
The ventilator disclosed herein has many advantages. Its
construction and simple an: it has only a few moving parts. It can
be used anyWhere that a supply of compressed air is available. No
electrical connections are required. It is completely automatic and
dependable in operation. The ventilator also automatically relieves
the pressure in the patient's lungs if it becomes excessive and
periodically gives the patient an extra supply of air. If the
patient inhales of his own accord, the controls are overriden and
he is immediately supplied with the necessary amount of air.
According to the provisions of the patent statutes, I have
explained the principle of my invention and have illustrated and
described what I now consider to represent its best embodiment.
However, I desire to have it understood that, within the the
appended claims, the invention may be practiced otherwise than as
specifically illustrated and described.
* * * * *