Container assembly having coupling lugs

Abstract

A container assembly for use as a sampling device for microorganisms includes a base member and a lid removably coupled to the base member. The lid includes a top wall and a side wall depending from the top wall. The base member has a side wall with an outer surface that complements the inner surface of the side wall of the lid. A plurality of lugs are formed on the outer surface of the base member to provide a gripping force to secure the lid to the base member. The gripping force is provided by the surface area of the lugs so that the lid is secured to the base member while enabling the lid to be readily removed from the base member without sticking or binding. The lugs are odd in number, are uniformly spaced around the side wall of the base member, and are dimensioned to provide a point of contact with the outer wall of the lid causing the wall of the lid to flex outwardly at the point of contact so that the distortion and flexing of the wall of the lid provide a resilient gripping force against the lugs of the base member. The lugs are spaced apart a distance so that the wall of the lid is able to flex inwardly between adjacent points of contact between the lugs and the wall of the lid when the lid is distorted. In one embodiment, three lugs are provided and uniformly spaced apart so that no two lugs are diametrically opposed from one another and a point of contact and outward deflection of the wall of the lid is diametrically opposed to an area of inward deflection of the wall of the lid.

1 . A container assembly comprising: 
 a base member having a bottom support surface, a continuous side wall surrounding said bottom support surface and extending in a direction away from said bottom support surface to define a height of said side wall, and a plurality of lugs protruding outwardly from an outer surface of said continuous side wall; and    a lid having a substantially planar surface, a continuous side wall having an inner surface with an inner dimension complementing an outer dimension of said continuous side wall of said base member, said lugs on said continuous side wall of said base member being spaced apart such that said continuous side wall of said lid deflects outwardly in a contact area of said lugs and deflects inwardly in an area between adjacent lugs on said side wall of said base member.    
   
   
       2 . The assembly of  claim 1 , wherein said lugs are uniformly spaced apart.  
   
   
       3 . The assembly of  claim 1 , wherein an odd number of said lugs are provided on said outer surface of said side wall and where said lugs have a dimension to contact an inner surface of said continuous side wall and apply a substantially uniform outward gripping force to said continuous side wall of said lid.  
   
   
       4 . The assembly of  claim 3 , wherein said lugs are spaced to define an area for inward deflection of said lid between adjacent lugs of said base and where each of said lugs are diametrically opposed to an area for inward deflection of said lid.  
   
   
       5 . The assembly of  claim 1 , wherein said side wall of said base includes three of said lugs uniformly spaced apart around said base.  
   
   
       6 . The assembly of  claim 1 , wherein said side wall of said base includes five of said lugs uniformly spaced apart around said base.  
   
   
       7 . The assembly of  claim 1 , wherein said side wall of said base includes an odd number of said lugs uniformly spaced around said base and where said lugs have a longitudinal dimension, a width and a convex outer surface with a surface area sufficient to define a friction fit with said lid.  
   
   
       8 . The assembly of  claim 7 , wherein each of said lugs have a width and a radial dimension sufficient to deflect and deform said side wall of said lid to grip said lid without cracking or breaking said lid and where said continuous side wall of said lid contacts said lugs without contacting said continuous side wall of said base member when said lid is placed on said base member.  
   
   
       9 . The assembly of  claim 1 , wherein said side wall of said base and said lugs are dimensionally stable when said lid is placed on said base.  
   
   
       10 . The assembly of  claim 1 , wherein said base includes a lid support surface extending in an outward direction from said side wall of said base for supporting said side wall of said lid.  
   
   
       11 . The assembly of  claim 10 , wherein said side wall of said lid includes a flange having a plurality of spaced apart protrusions to space said flange from said lid support surface when said lid is placed on said base.  
   
   
       12 . The assembly of  claim 1 , wherein each of said lugs have a first bottom section having a substantially cylindrical shape and a substantially semi-spherical top section.  
   
   
       13 . The assembly of  claim 1 , wherein each of said lugs have a first bottom section with a first radial dimension and a second top section with a second radial dimension, where said first radial dimension is greater than said first radial dimension.  
   
   
       14 . The assembly of  claim 1 , wherein said side wall of said base is substantially annular and where said lugs have a height that is about one-half a height of said side wall.  
   
   
       15 . A container assembly for use in sampling a surface for the presence of microorganisms, comprising: 
 a base having a bottom support surface for supporting a sampling media, a continuous side wall surrounding said bottom support surface and extending away from said bottom support surface to define a height of said continuous side wall, and an odd number of lugs protruding outwardly from an outer surface of said continuous side wall, and a peripheral lid support surface extending outwardly from said continuous side wall; and    a lid having a substantially planar surface, a continuous side wall extending from said planar surface and having an inner surface and an inner dimension to be placed on said base and overlie said side wall of said base, said lugs on said side wall of said base having a dimension to contact said inner surface of said side wall of said lid and being spaced apart a distance to deflect said side wall of said lid outwardly at a point of contact with said lugs and to deflect said side wall of said lid inwardly in an area between said lugs.    
   
   
       16 . The container assembly of  claim 15 , wherein said lugs are uniformly spaced apart to define an area for inward deflection of said lid whereby said side wall of said lid deflects inwardly into said area when said lugs mate with said inner surface of said side wall of said lid.  
   
   
       17 . The container assembly of  claim 15 , wherein each of said lugs have a contact surface area for contacting said inner surface of said side wall of said lid and where said contact surface area is sufficient to grip said base.  
   
   
       18 . The container assembly of  claim 17 , wherein said lugs have a dimension to grip said side wall of said lid with a gripping force that is about twice the weight of said base.  
   
   
       19 . The container assembly of  claim 15 , wherein said side wall of said base includes three of said lugs uniformly spaced apart around said base whereby said lugs define three points of contact with said lid and deflect said side wall of said lid outwardly at said three points of contact to define a resilient gripping force.  
   
   
       20 . The container assembly of  claim 15 , wherein said side wall of said base includes five of said lugs uniformly spaced apart around said base whereby said lugs define five points of contact and outward deflection of said inner wall of said lid to define a resilient gripping force.  
   
   
       21 . The container assembly of  claim 15 , wherein said lugs are uniformly spaced around said base and where said lugs have a longitudinal dimension, a width and a convex outer surface having a surface area sufficient to form a friction fit with said lid.  
   
   
       22 . The container assembly of  claim 15 , wherein said lid is made of polystyrene and where said lugs have a width and a radial dimension sufficient to deflect and deform said side wall of said lid without cracking or breaking said lid.  
   
   
       23 . The container assembly of  claim 22 , wherein said side wall of said base and said lugs remain dimensionally stable when said lid is placed on said base.  
   
   
       24 . The container assembly of  claim 15 , wherein said side wall of said lid includes an outwardly extending radial flange, said flange having a plurality of spaced apart protrusions to contact said peripheral lid support on said base when said lid is placed on said base.  
   
   
       25 . The container assembly of  claim 15 , wherein each of said lugs have a first bottom section contiguous with said lid support surface, a substantially convex outer surface and a top section with a substantially semispherical surface.  
   
   
       26 . The container assembly of  claim 15 , wherein each of said lugs have a height that is about one-half a height of said side wall of said base.