Abstract:
An earplug ( 10 ) of the type that is molded of elastomeric material and that has a flange ( 14 ) that seals to the walls of a person&#39;s ear canal as a stem ( 12 ) is pushed forward into the ear canal. Instead of using three or four flanges, applicant&#39;s earplug has a single very long main flange ( 14 ) with a maximum diameter (D) that is at least 80% of the length (L) of the main flange, and at least 55% of the entire length (B) of the earplug except for the stem. This allows the outside of the long flange to extend at a very small angle (C) to the axial direction, and apply a constant force against the walls of the ear canal, for good and comfortable sealing to the ear canal.

Description:
CROSS-REFERENCE 
       [0001]    Applicant claims priority from U.S. Provisional patent application Ser. No. 60/784,341 filed Mar. 21, 2006. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Two major types of earplugs are foam earplugs and flange earplugs. Flange earplugs are usually molded of nonfoam elastomeric material and rely on the radially inward deflection of thin flanges to seal to the walls of the ear canal. Two widely sold flange earplugs are described in U.S. Pat. Nos. 4,867,149 and 6,241,041. These earplugs each have a stem and three tapered flanges that each can be inwardly deflected by the walls of a person&#39;s ear canal. The three flanges include a rearward flange of greatest diameter at its rear end, a front flange of smallest diameter at its rear end, and a middle flange of an in between diameter at its rear end. The three flanges are provided to seal well to ear canals of different diameters. Most ear canals vary in diameter between about 0.33 inch (8.4 mm) and 0.27 inch (6.86 mm), with some ear canals being of elliptical cross-section instead of circular, and with the axis of many ear canals curving. 
         [0003]    It is recognized in U.S. patent application Ser. No. 10/778658 that it is desirable that the rear parts of flanges that will engage the ear canal, extend at small angles to the surfaces of the ear canal. That patent application achieves this by extending front parts of the flanges primarily radially, to locate the rear parts near the ear canal surface. However, the flanges are not as resilient as would be desired. An earplug of the flange type, that assured low pressure, wide area, contact of a flange with the ear canal walls for ear canals of a variety of sizes, would be of value. 
       SUMMARY OF THE INVENTION 
       [0004]    In accordance with one embodiment of the present invention, a flanged earplug is provided that is integrally molded of resilient material, and which assures low pressure, wide area flange contact with the surface of an ear canal for ear canals of a variety of sizes. The earplug has a front end part, a stem that extends rearward along the earplug axis from the front end part, and a main flange that extends at a rearward and radially outward incline from the front end part. The main flange rear end has a flange outside diameter of about 0.50 inch (12.7 mm), which is typical for a prior art earplug flange. However, the main flange has a length that is at least 80% of the length of the main flange and at least 55% of the length of the earplug other than the stem. This very long length results in the main flange having high resilience, with its rear end extending almost parallel to the axis, so the rear end is easily deflected radially inward by an ear canal. Because of the long length of the main flange, both its front portion and its rear portion can extend primarily parallel to the axis. 
         [0005]    An internal flange can be provided that lies within the main flange and that bears against the inside surface of the main flange to bias it radially outward. A backup flange can be provided that lies in front of the main flange and that is of short axial length. The backup flange can seal to a small diameter ear canal even if the main flange is only partially inserted into the ear canal, or if the main flange does not provide a sound seal for some other reason. 
         [0006]    The novel features of the invention are set forth with particularity in the appended claims. The invention will be best understood from the following description when read in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is an isometric view of an earplug of one embodiment of the invention. 
           [0008]      FIG. 2  is a sectional side view of the earplug of  FIG. 1 . 
           [0009]      FIG. 3  is a sectional view taken on line  3 - 3  of  FIG. 2 . 
           [0010]      FIG. 4  is a sectional view of the earplug of  FIG. 2  during insertion of the earplug into a person&#39;s ear canal, and showing, in phantom lines, the ear plug inserted slightly further into the ear canal. 
           [0011]      FIG. 5  is a sectional view of an earplug of another embodiment of the invention, wherein the earplug includes internal flanges that lie within the main flange. 
           [0012]      FIG. 6  is a sectional isometric view of the earplug of  FIG. 5 . 
           [0013]      FIG. 7  is an isometric view showing the earplug of  FIG. 6  after it is molded but before two of the flanges are reversed to achieve the final configuration of  FIG. 6 . 
           [0014]      FIG. 8  is a sectional side view of an earplug of another embodiment of the invention wherein the earplug includes a short backup flange that lies forward of the main flange. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0015]      FIGS. 1 and 2  illustrate an earplug  10  of the invention which is of simple construction and which seals well to ear canals of different diameters. The earplug includes a stem  12  and a main flange  14  that each extends rearward R along an axis  16  of the earplug from a front end part  20  of the earplug. The main flange has a progressively greater diameter at progressively more rearward locations. The main flange has an inside  22  that joins to the stem at a location  24 , and the main flange has an outside  30  that merges with the front end part to form a smooth convexly curved earplug front end outside surface  32 . The earplug is symmetric about the axis  16 . 
         [0016]    The ear canal A shown in  FIG. 4  has an entrance with a diameter B such as 0.30 inch. Most people have ear canals with an entrance diameter of between about 0.33 inch (8.4 mm) and 0.27 inch (6.86 mm). There is also variation in the cross-sectional shape of the ear canal (slightly elliptical instead of round) and the axes of many ear canals are curved. The rear end  48  of the main flange  14  of  FIG. 1  has an initial diameter D of about 0.48 inch (12.2 mm) and is expected to be radially compressed (with respect to axis  16 ) to press firmly against the internal surface of the ear canal. The earplug is molded of an elastomeric material such as silicone having a durometer A of about 30. It is desirable that the total expansion force of the flange against the walls of the ear canal be about two ounces. This assures sufficient radially inward deflection of the flange rear portion  40  so the flange presses firmly against the ear canal at all locations around the flange to prevent the passage of sound around the flange. This also avoids large forces that can bring discomfort to the wearer. 
         [0017]    The single long flange  14  has high resilience because of its length. As a result, the flange rear portion  40  applies a primarily constant force against the ear canal despite the flange bearing against walls of a small ear canal (e.g. diameter B of 0.27 inch) or a large ear canal (e.g. diameter B of 0.33 inch). It is desirable that the flange bear with about the same force (e.g. 2 ounces, or 54 grams) against small and large diameter ear canal walls. If the flange had a smaller length L, such as about half its maximum undeflected diameter D, then the force of the flange rear portion against the ear canal walls would vary more with variation of the ear canal diameter. 
         [0018]    Prior earplug flanges, such as those shown in U.S. Pat. Nos. 4,867,149 and 6,241,041 had flange lengths no more than 62% of their largest diameters, resulting is less resilience and therefore a greater change in force with ear canal diameter. Applicant prefers to use a main flange length L that is at least 80%, of the undeflected main flange largest diameter D, that is preferably at least 90% of the diameter D, and that is more preferably at least 100% of the diameter D. 
         [0019]    The flange  14  has a thickness T that varies along its length. The thickness is greatest at the front end  44  of the flange and gradually decreases towards the rear of the flange. The thinner flange rear portion allows better conforming of the flange rear portion to irregularities in the ear canal walls, while the thicker flange front portion provides greater resistance to deflection that balances the smaller force of the thin flange front portion. It is desirable that there be substantial radially inward deflection of the rear of the flange, to assure that it presses firmly against the surface of the ear canal. 
         [0020]    The stem  12  is used to insert the earplug into the ear and to withdraw it. The stem usually extends rearward of the main flange, and its diameter does not have much effect on the earplug. Applicant has constructed earplugs of the construction shown in  FIGS. 1-4 . The earplugs had a main flange outside diameter D of 0.48 inch and a main flange length L of 0.53 inch, for a diameter-to-length ratio of 110%. The entire length G of the earplug front portion (not including the stem) between the extreme front end  46  of the front end part and the rear end  48  of the main flange was 0.63 inch. The diameter D of the earplug rearmost flange, which is the main flange  14 , is at least 55%, preferably at least 65% and most preferably at least 75% of the entire length G of the earplug front portion, that is, up to the rear end  48  of the main flange (which is the flange of greatest length). The angle C between the main flange outside surface and a line  49  that is parallel to the axis  16 , varies from about 25° at the flange front end  44  to about 5° at the flange rear end  48 . The main flange rear end diameter should be between 0.35 inch and 0.60 inch, and the main flange axial length should be at least 0.45 inch. 
         [0021]      FIGS. 5  though  7  illustrate an earplug  50  that is similar to that of  FIG. 1 , except that it includes internal flanges  52 ,  54  that radially-outwardly bias a location  55  (a ring-shaped location) on the main flange  56 . The rearward internal flange  52  has a rear end  62  that merges with the stem, a front end  64  that bears against the inside  58  of the main flange, and a middle portion  66 . The rearward internal flange  52  biases the middle  55  of the main flange radially outward. This results in the main flange rear portion  72  pressing more firmly against the ear canal without requiring a thicker flange, so a thin main flange can be used that conforms to local irregularities in the ear canal. The rearward internal flange has a considerable length J and thin walls especially at its front end  64  so it is highly resilient. 
         [0022]    The forward internal flange  54  is thin and of length K. Its rear end  80  urges the middle of the rearward internal flange radially outwardly. The combination of the main flange with one or both of the internal flanges, results in resilient outwardly biasing of the main flange. 
         [0023]      FIG. 7  shows how the one-piece molded earplug  50  of  FIGS. 5 and 6  can be molded, with the main flange  56  initially opening forwardly and the two umbrella-shaped internal flanges  52 ,  54  opening rearwardly. After molding, the rear end portion  64  of the rear internal flange  52  is deflected to “snap” it in reverse so it opens forwardly as in  FIG. 5 . Then the main flange  56  is “snapped” in reverse so it opens rearwardly as in  FIG. 5 . 
         [0024]    Although the earplugs with the long main flange  14  of  FIG. 1  and the long main flange  56  of  FIG. 5  can provide good sound sealing, they lack a “backup”, or second location where the earplug seals to the walls of the ear canal. Such a backup location has an advantage in providing a sound seal in the event that there is an irregularity in the ear canal, such as a small bump where the main flange rear portion presses against the ear canal and where an air gap might be left, or where the earplug is inserted only a small part of the total designed insertion distance into the ear canal. 
         [0025]      FIG. 8  illustrates an earplug  90  that includes a main flange  92  and a backup flange  94  that “piggybacks” on the main flange. The main flange  92  is similar to those of the prior two embodiments of the invention, with a length M along the earplug axis  100  that is over at least 75%, preferably at least 90%, and more preferably at least 100% of the main flange maximum outside diameter N. The backup flange  94  has a front end  102  that lies slight forward of the main flange and merges with an earplug front part  104 . The backup flange has a rear end  106  that has about the same diameter as the rear of the main flange. However, the backup flange has an average thickness P that is about half the average thickness Q of the main flange and slightly more sound can penetrate the backup flange. In most cases, the main flange seals well against the ear canal walls and the backup flange seals also, though not quite as well. However, when the main flange does not seal well, the moderately good sealing of the backup flange protects the hearing of the worker from damage. 
         [0026]    Applicant prefers to mold the earplug of a “solid” (not foam) elastomeric material such as silicone. However, it is possible to mold the earplug of a foam material, preferably one of a high density foam. In either case, the earplug is a one-piece molded article. 
         [0027]    Thus, the invention provides an earplug of a type that has a stem and that has a flange that extends at a rearward and radially outward (with respect to the axis) incline as seen in a sectional view, wherein the flange has an especially high resilience so it can provide a force on the order of magnitude of two ounces against the ear canal despite variation in the diameter of the ear canal. This is accomplished by using a main flange that extends along most of the length of the earplug other than the stem, with the main flange length being at least 80% (more than 75%), 90% or 100% of the largest diameter of the main flange. The resilience of the main flange can be enhanced by providing an internal flange that extends from the stem, preferably at an average incline of no more than 30° to the axis, and that presses against the inside surface of the main flange to resiliently bias it radially outward. A second internal flange can bias the first internal flange outward. The earplug can be provided with a backup flange that has about the same or slightly smaller rear portion diameter but a smaller length and thickness than the main flange. Such backup flange assures a moderate sound seal in the event that the main flange does not provide a good sound seal. 
         [0028]    Although particular embodiments of the invention have been described and illustrated herein, it is recognized that modifications and variations may readily occur to those skilled in the art, and consequently, it is intended that the claims be interpreted to cover such modifications and equivalents.