Breathing apparatus

A demand regulator for use in underwater breathing employs a longitudinally movable tubular valve member having a transversely opening outlet orifice which is moved relative to the breathing port of the regulator as the valve member is moved axially between the fully opened and fully closed positions.

The present invention relates in general to pressure regulation in 
breathing systems such as the type used, for example, in SCUBA diving, and 
it relates more particularly to a new and improved means for improving the 
breathing characteristics of a demand type pressure regulator by 
automatically varying the venturi action in the regulator as the valve 
moves between a closed position and a fully open position. 
BACKGROUND OF THE INVENTION 
Pressure regulators such as those used in underwater breathing apparatus 
commonly employ the pressure differential between the ambient and a 
breathing chamber in the regulator to operate an air valve which supplies 
air to the breathing chamber. This is accomplished by mounting a flexible 
diaphragm across an opening in the wall of the breathing chamber and using 
the diaphragm to actuate the air valve. Since the breathing tube is 
connected to the breathing chamber, the diver breaths from the breathing 
chamber, and in single hose regulators the diver also exhales through the 
breathing chamber to the ambient. 
When the diver commences to inhale while the air valve is closed, the 
pressure in the breathing chamber is reduced causing the diaphragm to be 
sucked into the breathing chamber and thereby to open the air inlet valve. 
When the user exhales, the pressure in the breathing chamber increases to 
cause the diaphragm to move out and thereby to close the air inlet valve. 
In order to reduce the effort required to breath from such regulators it 
is common practice to design the regulator so that a portion of the inlet 
air travels as a jet directly into the breathing tube, thereby to provide 
a so-called venturi effect which educts air from the breathing chamber and 
prevents the pressure in the breathing chamber from rising above ambient 
pressure. Consequently, the diaphragm is held in the pulled-in position by 
the venturi action and holds the air inlet valve open. While such a 
venturi effect makes it easier for the user to inhale from the regulator, 
exhaling becomes more difficult inasmuch as the venturi action must be 
overcome before the air inlet valve can be closed. Accordingly, the amount 
of venturi action provided must be carefully adjusted for optimum 
inhalation and exhalation. 
In U.S. Pat. No. 4,140,113 there is described a demand regulator having a 
movable deflector for deflecting an increasingly greater portion of the 
inlet air away from the breathing tube as the air inlet valve is moved 
from the fully closed position to the fully opened position. The greatest 
portion of the inlet air is thus deflected away from the mouthpiece tube 
when the air inlet valve is fully open and the venturi action would 
otherwise be at a maximum. In actual practice the air inlet valve does not 
move to the fully open position during normal operation of a demand 
regulator. When, however, the air in the supply tank is nearly exhausted 
and the pressure of the air being supplied to the demand regulator is thus 
less than normal, i.e., the intermediate pressure is less than 140 p.s.i., 
the air inlet valve may move to the fully open position in an attempt to 
meet the inhalation demands of the diver. Under such circumstances the 
venturi action is relatively low because of the low air velocity wherefor 
it is unnecessary to deflect any of the inlet air away from the breathing 
tube to reduce the venturi effect. 
In other types of demand regulators stationary deflectors are used to alter 
the direction of inlet air flow relative to the breathing tube and the 
breathing chamber within the regulator thereby to provide some venturi 
action for assisting the diver to inhale through the regulator. Since the 
venturi action is greatest when the air inlet valve is fully open and air 
flow is at a maximum, such regulators may have a tendency to free flow, 
and moreover, exhaling becomes more difficult inasmuch as the venturi 
action must be overcome before the air inlet valve will close. 
SUMMARY OF THE INVENTION 
Briefly, there is provided in accordance with the teachings of the present 
invention a new and improved method and means for automatically adjusting 
the distribution of air between a breathing tube and the breathing chamber 
in a demand regulator as the air inlet valve moves between the closed 
position and the fully open position. In a preferred embodiment of the 
invention the air inlet valve employs a tubular valve member which is 
moved in a longitudinal direction toward and away from an associated valve 
seat, and which has an air inlet orifice in the side for directing the 
stream of inlet air toward the breathing tube. The inlet orifice thus 
moves relative to the breathing tube as the air inlet valve opens. 
Preferably the movable tubular inlet valve is used in combination with a 
movable or stationary venturi control deflector so as to provide better 
control of the distribution of the air as the valve is moved between the 
fully open position and the fully closed position. In this manner a 
decreasing amount of venturi action is provided as the valve opens from 
the closed position to the normally open position, but substantially all 
of the inlet air flows directly into the breathing tube when the valve is 
fully open as in an emergency. 
An added advantage of the tubular inlet valve is the fact that it is 
unbalanced toward the open position once the valve member has moved away 
from the seat. Consequently, a lesser amount of venturi action is required 
to hold the valve open to facilitate inhalation by the user.

DETAILED DESCRIPTION OF THE INVENTION 
Referring to FIGS. 1 and 2, there is shown a demand type breathing 
regulator 10 constituting a preferred embodiment of the invention. The 
regulator 10 is of the single hose type used in SCUBA diving and it 
controls the flow of air from a source of pressurized air (not shown) 
connected to the inlet 12 and a breathing tube 14 through which the diver 
breaths while under water. Ordinarily a mouthpiece is fitted to the outer 
end of the tube 14. 
The source of air generally comprises a first stage regulator connected to 
an air tank carried by the diver. The first stage regulator reduces the 
pressure of air exiting the tank to an intermediate pressure of about 140 
p.s.i. which remains substantially constant as the air in the tank is used 
and the tank pressure drops from about 3000 p.s.i., to 140 p.s.i. Under 
normal diving conditions the diver will surface before the tank pressure 
falls below 140 p.s.i. wherefor the air inlet pressure to the regulator 10 
is a constant 140 p.s.i. As discussed above, however, there are occasions 
when the tank pressure falls below 140 p.s.i. wherefor the inlet pressure 
to the regulator 10 is less than 140 p.s.i. 
The regulator 10 may be seen to comprise a cup-shaped housing member 16 
having a bottom wall 18 into which the breathing tube 14 opens. It will be 
understood by those skilled in the art that a soft mouthpiece (not shown) 
fits over the distal end of the breathing tube 14 for receipt in the mouth 
of the user to provide a sealed connection between the tube 14 and the 
diver's mouth. A pair of flapper type check valves 20 are also mounted in 
the housing member 16 and these valves permit air to be exhausted from the 
breathing chamber in the regulator to the ambient. 
An air inlet valve 22 is mounted in the side wall of the housing member 16 
and controls the supply of air from the inlet 12 to the mouthpiece tube 
14. As more fully described hereinafter the valve 22 is operated by means 
of a pivotably mounted actuator lever 26 which is in turn actuated by a 
flexible diaphragm 28 sealably mounted across the upper open end of the 
housing member 16. An apertured cover 20 is mounted to the housing member 
16 over the diaphragm 28 and is held in place by a suitable clamp ring 32. 
An emergency manual actuator button 34 is carried by the cover and may be 
used for manually overriding the diaphragm and opening the air inlet valve 
22. A coil spring 37 biases the actuator 34 into the inoperative position 
as illustrated in FIG. 1. 
When the valve 22 is open, air flows from the inlet 12 into the regulator 
with a portion of the air going directly against a deflector baffle 36 
mounted in the tube 14 and extending a short distance into the breathing 
chamber within the housing 16 between the bottom wall 18 and the diaphragm 
28. The baffle 36 redirects the air stream from the inlet orifice into the 
breathing tube to the mouth of the diver. That portion of the inlet air 
which does not flow directly into the breathing tube enters the breathing 
chamber and increases the pressure therein. The airstream flowing directly 
into the breathing tube produces a venturi action which educts air from 
the breathing chamber to maintain the pressure therein below the ambient 
and thereby to assist the diver in holding the air inlet valve open during 
inhalation. 
In my earlier U.S. Pat. No. 4,140,113 there is disclosed the use of a 
movable deflector baffle which moves across the inlet opening as the inlet 
valve moves toward the fully open position. Since the venturi effect is 
proportional both to air velocity and air volume, and the volume increases 
as the inlet valve moves toward the fully open position under normal 
operating conditions, the baffle functions to decrease the portion of the 
inlet air flowing directly into the breathing tube as the air inlet valve 
member moves from the fully closed position to the fully open position. 
In accordance with a feature of the present invention, the airstream 
flowing directly into the breathing tube when the air inlet valve member 
is in a less-than fully open, yet substantially open, position is 
minimized by a deflector baffle, but as the inlet valve opens further the 
airstream flowing directly into the mouthpiece is again increased. 
Consequently, when the air supplied to the regulator is at the normal 
intermediate pressure value of, for example 140 p.s.i., and the inlet 
valve is in the open position for normal inhalation, the ratio of air 
directly entering the breathing tube to air directly entering the 
breathing chamber is at a minimum. When, however, the air pressure to the 
regulator is less than normal, as for example when the air supply is 
nearly exhausted, the pressure in the breathing chamber is not appreciably 
greater than ambient pressure and the inlet valve member is moved beyond 
its normally open position to its absolutely fully open position. When the 
inlet valve member is in this latter position the entire inlet air stream 
flows directly into the breathing tube to provide a maximum venturi 
effect. 
Referring to FIGS. 1 and 2, it may be seen that the air inlet valve 22 
comprises a generally tubular housing 40 which extends through an opening 
in the side wall 42 of the regulator housing and is sealably fixed thereto 
as by means of a brazing operation. The valve housing 40 further includes 
a tubular sleeve portion 44 provided with an internally threaded portion 
46 at its distal end. A pair of rectangular openings 48 and 49 are 
respectively provided in opposite sides of the sleeve portion 44 to 
receive the inner ends of a pair of rectangular arms 51 and 52 of the 
valve actuator 26. A tubular valve element 54 having an axial passageway 
55 therein has an external annular flange 56 which is spring biased 
against the arms 51 and 52 by a coil spring 58 held in compression between 
the flange 56 and a retainer screw 60 threaded into the end of the sleeve 
portion 44 of the valve housing. The retainer screw 60 may be used to 
adjust the closing force exerted by the spring 58 on the valve element 54. 
The valve member 54 slidably extends through a circular opening 62 defined 
by an internal annular flange 64 in the housing 40, and its open end 66 is 
in sealing engagement with a resilient valve seat 68 mounted at a fixed 
position within the housing 40. Preferably the wall of the valve member 54 
is cut at a sharp angle at the end 66 so as to assure a good seal with the 
valve seat 68. The valve seat 68 is formed of an elastomeric material and 
the force of the spring 58 partially embeds the sharp end 66 of the valve 
member 54 into the surface thereof. As shown, the seat 68 is mounted in a 
cylindrical recess 70 in a spider 72 which is threaded into the inlet end 
of the housing 40. An elastomeric 0-ring 74 is captured between the flange 
64 and a washer 78 and provides a hermetic seal between the valve member 
54 and the housing 40. 
In FIGS. 1 and 2 the valve member 54 is shown in a closed position seated 
against the seat 68 wherefor air supplied to the inlet 12 does not enter 
the passageway 55 through the valve member. When, however, the pressure in 
the breathing chamber is reduced below ambient the diaphragm 28 moves into 
the breathing chamber and causes the actuator 26 to pivot in a 
counterclockwise direction, as shown in FIG. 1, about the lower outer 
corners 76 of the openings 48 and 49. The actuator arms 51 and 52 thus 
press against the flange 56 to move the valve member 54 in an axial 
direction away from the seat 68 whereby the inlet air flows into the 
passageway 55 through the open end 66 thereof. The actuator assembly is 
similar to that described in U.S. Pat. No. 3,633,611. 
The passageway 55 extends through the valve member 54 and opens in a 
lateral direction at an outlet orifice 80 which faces toward the breathing 
tube deflector baffle 36. As best shown in FIG. 2, the walls of the 
passageway 55 provide a smooth transition between the axial portion and 
the transverse portion thereby to ensure a laminar flow of air through the 
valve member. When the air inlet valve is open the air striking the curved 
end wall portion 55a of the passageway 55 exerts a force on the valve 
member 54 opposing the force of the spring 58 thereby assisting the diver 
in holding the valve open during inhalation. 
In order to reduce the venturi action as the valve member 54 moves from the 
closed position toward the normally open position, a baffle-like deflector 
82 depends from the actuator 26 for movement between the air outlet 
orifice 80 and the breathing tube deflector 36. In the regulator disclosed 
in my U.S. Pat. No. 4,140,113 the air outlet orifice is in a fixed 
position wherefor changes in the venturi action are caused solely by the 
movable deflector. In the regulator of the present invention, however, the 
outlet orifice is carried by the valve member and it also changes the 
venturi action as the valve member moves between the opened and closed 
positions. As may be seen from an inspection of FIG. 3, the deflector 82 
is in front of the orifice 80 and thereby deflects a substantial portion 
of the inlet airstream into the breathing chamber when the valve member is 
in the normal open position. When the valve member moves beyond the 
normally open position into the fully open position shown in FIG. 4, a 
lesser portion of the inlet airstream is directed against the deflector 82 
and thus is deflected into the breathing chamber, thereby increasing the 
venturi action and making it easier for the diver to breath. 
It will be apparent to those skilled in the art that the deflector 82 can 
be shaped to provide this same effect with a stationary air outlet 
orifice. However, the provision of the outlet orifice in the tubular valve 
member itself provides added advantages such as better control of the 
distribution of the air exiting the air outlet, less obstruction of the 
air flowing through the inlet valve into the breathing chamber and 
breathing tube, and use of the inlet air pressure to urge the valve member 
toward the open position. 
The use of a tubular valve member having the outlet in the side can also be 
used in combination with a stationary, venturi control deflector positoned 
between the breathing tube deflector and the inlet orifice in the side of 
the valve member so as to intercept a maximum portion of the inlet air 
when the need for the venturi effect is at a minimum. In this embodiment 
of the invention the stationary deflector is located opposite the air 
outlet orifice only when the valve member is in the normal open position. 
Therefore when the air inlet valve first opens, the airstream flowing from 
the orifice goes directly to the breathing tube via the breathing tube 
baffle 36 and is not obstructed by the stationary, venturi control 
deflector. Similarly, when the air supply is low and the valve member 
moves beyond the normal open position to the fully open position, the 
airstream flowing from the outlet orifice to the breathing tube is 
unobstructed. 
During use of the regulator the friction between the spring 58 and the 
flange 56 prevents the valve member 54 from rotating. However, with the 
diaphragm removed the valve member 54 can be rotated by means of a tool 
for adjusting the angular position of the outlet air orifice. Rotational 
adjustment of the valve member may thus be used to set the angle of the 
inlet airstream relative to the breathing tube deflector baffle 36 and/or 
the venturi control deflector whether it be movable or stationary. In this 
manner the venturi action can be precisely adjusted. 
While the present invention has been described in connection with 
particular embodiments thereof, it will be understood by those skilled in 
the art that many changes and modifications may be made without departing 
from the true spirit and scope of the present invention. Therefore, it is 
intended by the appended claims to cover all such changes and 
modifications which come within the true spirit and scope of this 
invention.