Surgery – Respiratory method or device – Face mask covering a breathing passage
Reexamination Certificate
1999-07-21
2002-05-28
Weiss, John G. (Department: 3761)
Surgery
Respiratory method or device
Face mask covering a breathing passage
C128S206150, C128S200270, C128S200280, C128S205240, C128S201280
Reexamination Certificate
active
06394091
ABSTRACT:
TECHNICAL FIELD
This invention relates to devices for delivering breathing air to a user. Specifically, this invention relates to a breathing apparatus for use in toxic environments that delivers breathing air to a user through a mask which is maintained at a positive pressure.
BACKGROUND ART
Numerous types of devices for delivering breathing air to a user are known in the prior art. Such devices have different performance requirements depending on the circumstances in which they are intended to be used.
One critical application for air delivery devices are situations in which users are required to work in environments with toxic materials or gases. One group of workers who frequently are required to work under such conditions are firefighters. Breathing devices intended for use in toxic environments should minimize the risk of infiltration of toxic gases or materials into the lungs of a user.
Minimizing the infiltration of contaminants into an air delivery system used by a worker may be difficult due to the development of negative pressures when a worker inhales. Negative pressures developed in breathing masks or other delivery mechanisms may draw contaminants from the surrounding environment into the workers' air delivery system. The problem of infiltration of contaminants is particularly severe in situations where users engage in strenuous activity while wearing a breathing apparatus. Firefighters are commonly required to work under such conditions.
One approach that has been taken to minimize the risk of infiltration of contaminants into a breathing delivery system is the use of positive pressure breathing devices. Such devices deliver air to the user through a mask that effectively surrounds the user's nose and mouth. Air is delivered to the user through the mask at a positive pressure above atmospheric. Positive pressure is maintained so that the pressure in the mask is above atmospheric pressure at all times, and particularly while the user is consuming air by inhaling. By maintaining a positive pressure in the mask, any leakage of air will tend to be from the mask to the environment and not vice versa. This reduces the risk that contaminants will infiltrate the mask.
A variety of different approaches have been taken in the past to providing positive pressure in breathing devices. One approach has been to provide a breathing regulator that maintains a positive pressure in the mask at all times. When using a regulator of this type a user dons the mask, opens the regulator to a supply of air and the area in the mask quickly builds to a positive pressure. As the user inhales, air is delivered into the mask in sufficient quantity to maintain a positive pressure. When the user exhales, air from the user's lungs passes out of the mask through an exhaust valve. The exhaust valve opens at a pressure in excess of that which is maintained in the mask and closes when the pressure falls to the desired positive pressure level.
A problem with breathing devices of this type is that they only operate in a positive pressure condition. The user must control the flow of air to the mask with a manual valve. This poses drawbacks in that it may be difficult to place a valve within a user's easy reach. If the user must work wearing gloves or other protective equipment on their hands, it may be difficult to provide a valve that is readily manipulated. Another drawback is that a user in an emergency situation, may forget to open the air supply valve until contaminants have been drawn into the mask.
The problems associated with devices that operate only in a positive pressure mode have been reduced by breathing devices which have an “automatic-on” feature. Such breathing devices are capable of being placed in a standby mode in which no air flow occurs when they are off the user's face. When the user places a mask connected to an automatic-on type regulator device on his or her face and begins breathing, air is delivered to the mask. Once air delivery begins in response to a user's breathing, pressure in the mask automatically builds to a positive pressure.
Breathing devices which include the automatic-on feature eliminate the need to position a valve that can be manipulated by the user to begin the delivery of air. With automatic-on type devices, air is available as soon as the user begins to breathe. The risk that a user will put on his or her mask while forgetting to open a supply valve is also reduced. This is because the supply valve can remain open even when the breathing device is not planned for immediate use.
When a breathing apparatus that provides positive pressure is removed from the face, significant air will often escape. This is because the regulator operates to attempt to maintain a pressure above atmospheric in a confined space within a mask. As the mask is removed from the user's face the regulator delivers increasing amounts of air to try to build up a positive pressure until the regulator reaches a full flow condition. This may result in the loss of a significant amount of air until the user manually shuts off the airflow to the regulator.
In the past, mechanisms have been devised for breathing devices that provide automatic-on into positive pressure. These devices also provide for the manual shut off of airflow when the mask is removed from the face. Common mechanisms used for such purposes include toggle and latching levers and catch/release mechanisms. Such mechanisms respond to a user's inhalation to release a spring to act upon a diaphragm member which causes a valve to deliver air at positive pressure to a user. Such mechanisms must be mechanically re-latched to shut off the air delivery through the regulator.
Such prior art approaches have limitations and drawbacks. The drawbacks can include the limitations associated with the use of complex mechanisms for reliably and predictably releasing a flow of air in response to a user's inhalation effort.
Prior breathing devices have included a mask and a detachable regulator. In many devices having this configuration the regulator delivers air when the user inhales and provides an outlet path for air exhaled by the user. A regulator which operates in this manner is shown in U.S. Pat. No. 4,361,145. Fluid and condensation in the air exhaled by the user may collect in the regulator. Unless the regulator is disassembled and thoroughly cleaned after each use to eliminate contamination, diseases may be transmitted to subsequent users of the regulator.
Thus, there exists a need for a breathing apparatus for delivering air to a user that reduces contamination, provides automatic on into positive pressure and which conserves air when removed from the face.
DISCLOSURE OF INVENTION
It is an object of the present invention to provide a breathing apparatus for delivering air to a user.
It is a further object of the present invention to provide a breathing apparatus for delivering air to a user through a mask which maintains the mask at positive pressure.
It is a further object of the present invention to provide a breathing apparatus for delivering air to a user through a mask that causes the mask to automatically rise to a positive pressure in response to a user's breathing efforts.
It is a further object of the present invention to provide a breathing apparatus for delivering air to a user that minimizes the loss of air when removed from the user's face.
It is a further object of the present invention to provide a breathing apparatus which reduces contamination.
It is a further object of the present invention to provide a breathing apparatus for delivering air to a user that is durable and reliable.
Further objects of the present invention will be made apparent in the following Best Modes for Carrying Out Invention and the appended claims.
The foregoing objects are accomplished in the preferred embodiment of the invention by a breathing apparatus for supplying air to a user. The apparatus supplies air to a user at positive pressure in response to changes in pressure that result from
Jocke Ralph E.
Mendoza Michael
Scott Technologies, Inc.
Walker & Jocke
Wasil Daniel D.
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