Self-contained breathing apparatus

• US 4,640,277 A
• Filed: 05/17/1984
• Issued: 02/03/1987
• Est. Priority Date: 05/17/1984
• Status: Expired due to Fees

• Current Assignee: Texas College of Osteopathic Medicine Camp Bowie At Montgomery
• Original Assignee: Texas College of Osteopathic Medicine (University of North Texas)
• Inventors: Meyer, Steven D., Raven, Peter B.
• Primary Examiner(s): Recla, Henry J.
• Application Number:
  US06/611,507
• Time in Patent Office: 992 Days
• Field of Search: 128/204.21, 128/204.22, 128/204.23, 128/204.24, 128/204.25, 128/204.26, 128/204.28, 128/205.12, 128/205.13, 128/205.24 , 128/207.18, 128/207.16, 128/204.27
• US Class Current: 128/204.23
• CPC Class Codes: A62B 7/04 and lung-controlled oxygen or air valves

Abstract

This invention provides a self-contained user-actuated breathing device of the type used by industry and firefighters to protect against toxic atmospheres, which includes means for reducing user respiratory fatigue during periods of heavy physical exertion or stress, while maintaining facepiece pressure in a preselected narrow range of positive pressures relative to atmospheric to protect the user from ingress of toxic outside atmospheres. The invention includes a feedback mechanism responsive to facepiece pressure which actuates a supplemental second inlet air flow path to the facepiece during periods of high user demand. Also provided is a novel nonlinear expiration valve mechanism which is responsive to facepiece pressure to prevent facepiece pressure from exceeding a preselected positive level, thereby minimizing user expiratory fatigue which is commonly associated with such devices.

Claims

1. A portable, self-contained breathing device of the type which may be used by industry and firefighters to protect a user from toxic atmospheric conditions, comprising:

a facepiece which can be worn on the face of a user to isolate the breathing functions of said user from ambient atmosphere;

a supply of pressurized breathing air to be supplied to said facepiece in response to the inhalation demand of said user;

air flow regulator means between said facepiece and said supply, said regulator means including a first air flow path and second air flow path, said first air flow path including first means to permit air passage from said supply to said facepiece in response to facepiece pressure decreases below a first preselected level, said second air flow path including second means which permits additional air passage from said supply to said facepiece in response to facepiece pressure decreases below a second preselected level lower than said first preselected level; and

an electrical power supply;

said first air passage means comprising;

a first valve member,

and means hydraulically responsive to changes in pressure in said facepiece caused by the breathing functions of said user to control the opening and closing of said first valve member; and

said second air passage means comprising;

a second valve member,

pressure-sensitive means responsive to pressure changes in said facepiece, and

means for opening said second valve member in response to a signal from said pressure sensitive means that facepiece pressure has decreased below said second preselected level;

wherein said first air flow path is capable of of comfortably providing said user with the volume of breathing air required by said user during light to moderate physical exertion, and

said pressure sensitive means is electrically connected to said electrical power supply to generate an electrical signal when said facepiece pressure has decreased below said preselected level.

2. The device as set forth in claim 1, wherein said hydraulic control means comprises:

diaphragm means movably mounted adjacent said first air flow path to respond to changes in pressure in said facepiece, said diaphragm positioned to engage said first valve means during movement thereof.

3. The device as set forth in claim 2, wherein said second air flow path is capable of providing said user with an additional volume of breathing air sufficient to confortably meet requirements of said user during periods of heavy physical exertion.

4. The device as set forth in claim 1:

wherein said opening means comprises an electromechanical solenoid which opens said second valve member in response to said electrical signal from said pressure sensitive means.

5. The device as set forth in claim 4, wherein said pressure sensitive means is mounted within said facepiece.

6. The device as set forth in claim 5 further comprising:

first return spring means mounted to said first valve member to close said first valve member when said facepiece pressure increases above said first preselected level; and

second return spring means mounted to said second valve member to close said second valve member when said facepiece pressure increases above said second preselected level.

7. The device as set forth in claim 6, wherein said first preselected level is between about 0.5 inch (1.25 cm.) H₂ O and 1.5 inch (3.75 cm.) H₂ O above atmospheric pressure.

8. The device as set forth in claim 7, wherein said second preselected level is greater than atmospheric pressure.

9. The device as set forth in claim 8, further comprising:

means for controlling facepiece pressure during an exhalation cycle of said user, said controlling means comprising;

valve means movably positioned to permit communication between said facepiece and ambient atmosphere when said valve means is in an open position and to foreclose communication between said facepiece and ambient atmosphere when said valve means is in a closed position; and

means for moving said valve means between said open position and said closed position in response to facepiece pressure, said moving means and said valve means cooperating during said exhalation cycle to maintain said facepiece pressure below a third preselected level greater than said first preselected level and less than about 4 inches (10 cm.) H₂ O above ambient pressure, during periods of both light and heavy physical exertion of said user.

10. The device as set forth in claim 9, wherein said moving means comprises:

electrical power supply means;

pressure sensitive means mounted adjacent said facepiece, said pressure sensitive means electrically connected to said electrical power supply means to generate a signal when said facepiece pressure increases to said third preselected level; and

electromechanical solenoid means connected to said valve means and electrically connected to said pressure sensitive means to urge said valve means in response to said signal into a sufficiently open position to reduce said facepiece pressure below said third preselected level.

11. In a portable, self-contained breathing device of the type which may be used by industry and firefighters to protect a user from toxic atmospheric conditions, said device comprising a facepiece which can be worn on the face of a user to isolate the breathing functions of said user from ambient atmosphere, and a supply of pressurized breathing air to be supplied to said facepiece in response to the initiation of an inhalation cycle by said user, the improvement comprising:

means for regulating flow of said breathing air to and from said facepiece to maintain pressure within said facepiece at a level greater than ambient pressure and less than 4 inches (10 cm.) H₂ O above ambient pressure, throughout the breathing cycle of said user during periods of both light and heavy physical exertion;

said flow regulating means comprising;

inlet regulating means in communication between said air supply and said facepiece, said inlet regulating means including a first air flow path and a second air flow path, said first air flow path including first means to permit air passage from said supply to said facepiece in response to facepiece pressure decreases below a first preselected level, said second air flow path including second means which permits additional air passage from said supply to said facepiece in response to facepiece pressure decreases below a second preselected level lower than said first preselected level, and

expiration regulating means in communication between said facepiece and said ambient atmosphere, said expiration regulating means adapted to open communication between said facepiece and said ambient atmosphere when facepiece pressure increases to a third preselected level above said first preselected level during the exhalation cycle of said user, said expiration regulating means including feedback means responsive to facepiece pressure and adapted to control the degree of communication between said facepiece and said ambient atmosphere to maintain said facepiece pressure at a level less than 4 inches (10 cm.) H₂ O above ambient atmosphere during periods of both light and heavy exertion of said user,

a source of electrical power;

pressure sensitive means mounted in said facepiece and electrically connected to said electrical power source, said pressure sensitive means generating a first signal when facepiece pressure decreases to said second preselected level during an inhalation cycle, and a second signal when said facepiece pressure increases to a fourth preselected level greater than said third preselected level during an exhalation cycle;

first electromechanical solenoid means in said inlet regulating means and responsive to said first signal from said pressure sensitive means to open said second air flow path for the passage of additional air to said facepiece;

spring means in said expiration regulating means adapted to open communication between said facepiece and ambient atmosphere to a first measure in direct hydraulic response to the increase of facepiece pressure above said third preselected level; and

second electromechanical solenoid means connected to said expiration regulating means and responsive to said second signal from said pressure sensitive means to further open said communication when facepiece pressure reaches said fourth preselected level.