CROSS-REFERENCE TO RELATED
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/225,171 filed on Aug. 14, 2000 now abandoned.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a passive humidification apparatus, and more specifically to a humidifier for a continuous positive airway pressure (CPAP) device.
2. Relevant Prior Art
CPAP devices are now commonly used to treat a variety of respiratory disorders, including sleep apnea. CPAP devices normally consist of an air pump connected to a mask worn by a patient while they are sleeping.
Although CPAP devices have been very successful in treating these disorders, there is at least one associated drawback. The air that is introduced into the patient's respiratory system tends to have the effect of drying out mucous membranes. In order to mitigate this problem, several types of passive humidifiers have been developed that can be connected between the CPAP device and the associated mask without interfering with the normal operation of the device.
One such passive humidifier is disclosed in U.S. Pat. No. 5,231,979 to Rose et al. This humidifier consists mainly of a chamber having an inlet and an outlet and that is partially filled with water. In operation, the outlet of a CPAP device is connected to the inlet of the humidifier and the mask is connected to the outlet of the humidifier. When the air supplied by the CPAP device enters the humidifier chamber and passes over and contacts the water, some moisture is added to the air through evaporation before the air ultimately passes to the mask and into the patient. This humidifier, however, is very ineffective and normally produces insufficient levels of humidity.
To improve the efficacy of the passive humidification system, some such humidifiers have been provided with baffles located within the humidifier chamber. One such baffled humidifier is disclosed in U.S. Pat. No. 5,598,837 to Sirianne, Jr. et al. In this humidifier, air is made to flow around the baffles which increases its length of contact with the water and also tends to augment the evaporation process. However, this humidifier design still falls short of providing an optimum level of moisture in the output air. Additionally, the shape of this humidifier precludes most CPAP devices from resting on top of the humidifier, and thus it significantly increases the footprint of the CPAP system.
BRIEF SUMMARY OF THE INVENTION
According to one aspect of the present invention, a humidifier for a continuous positive airway pressure device is provided. The humidifier comprises a humidifier body, an air inlet provided to the humidifier body, an air outlet provided to the humidifier body, and a plurality of chambers defined within the humidifier body. The humidifier further comprises a plurality of baffles between one of the plurality of chambers and an adjacent one of the plurality of chambers, an opening provided between two of the plurality of baffles, the opening connecting the adjacent two of said plurality of chambers, and a deflector baffle being one of the
plurality of baffles, the deflector baffle being located proximate to the opening and defining a serpentine fluid flow path between the adjacent chambers.
According to another aspect of the present invention, a 5 humidifier comprises a non-planar dividing wall separating an adjacent two of said plurality of chambers, and an opening in the dividing wall providing fluid communication between chambers.
According to a further aspect of the present invention, a 10 humidifier comprises a base, a cover having a resilient peripheral portion removably securing the cover to the base, a chamber defined by the base and cover, an inlet in communication with the chamber, and an outlet in communication with the chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is perspective view of a CPAP humidifier according to an embodiment the present invention;
FIG. 2 is plan view of the CPAP humidifier of FIG. 1;
FIG. 3 is a plan view of a cover portion of the CPAP humidifier of FIG. 1;
FIG. 4 is a perspective view of the cover portion of FIG.
25 FIG. 5 is a detail of air flow within a CPAP humidifier according to an embodiment of present invention;
FIG. 6 is a sectional view taken along section line 6—6 of the CPAP humidifier shown in FIG. 2;
FIG. 7 is a sectional detail showing a seam of the CPAP 30 humidifier of FIG. 6;
FIG. 8 is a perspective view of a CPAP humidifier according to another embodiment of the present invention; and
35 FIG. 9 is a sectional detail taken along section line 9—9 of the CPAP humidifier shown in FIG. 8.
In a passive humidification system, factors contributing to
4Q humidification include increased surface contact and decreased air pressure. By controlling these factors through humidifier design, the overall performance of the humidifier can be increased.
One way to positively affect both of these factors is by
45 preventing laminar air flow through the system. When turbulence is introduced, the air does not travel in a straight line, and thus it will remain in the system longer and have increased surface contact with the water. Furthermore, assuming a constant input and output pressure, turbulent
5q flow has the effect of increasing airflow velocity within the system. When the velocity of the air flowing across the surface of the water is increased, the air pressure above the water correspondingly decreases which effectively increases the rate of evaporation. Turbulent airflow can be created in
55 several ways.
One way to create turbulence in a system is by designing the system with a high Reynolds number. As will be appreciated by one skilled in the art, the higher the Reynolds number, the greater the incidence of turbulent flow. The
60 Reynolds number of a system is directly related to the velocity of flow. In the present humidifier design, positive pressure is placed on the air inlet, thereby increasing the velocity of the air traveling through it.
Another way to increase turbulence and air velocity is by
65 providing baffles that redirect the airflow. Further, by constricting the airflow space, the baffles will tend to increase the Reynolds number of the system.