Lid for a tank of a fluid system, such as a cooling water circuit of an automotive vehicle

Abstract

The lid for a tank of a fluid system such as a cooling water circuit of an automotive vehicle is characterized in that the lid is composed of an inner lid member which can be screwed to the neck of the tank, and of an outer lid member which covers the inner lid member in the manner of a bell or mushroom, and that a coupling means is formed between the inner lid member and the outer lid member, the coupling means containing a medium which below a predetermined temperature or a predetermined temperature range shows such a consistency that the medium establishes a non-rotational connection between the outer lid member and the inner lid member while the medium above the predetermined temperature or the predetermined temperature range assumes such a consistency that the outer lid member is rotatable relative to the inner lid member. It is thereby ensured that endangerment of persons by hot liquid or coolant steam squirting out therefrom is reliably prevented.

1 . A lid for a tank of a fluid system such as a cooling water circuit of an automotive vehicle, comprising 
 an inner lid member which can be screwed to the neck of the tank, and an outer lid member which covers the inner lid member in the manner of a bell or mushroom, and a coupling means is formed between the lid member and the outer lid member, the coupling means containing a medium which below a predetermined temperature or a predetermined temperature range shows such a consistency that the medium establishes a non-rotational connection between the outer lid member and the inner lid member while the medium above the predetermined temperature or the predetermined temperature range assumes such a consistency that the outer lid member is rotatable relative to the inner lid member.    
   
   
       2 . The lid according to  claim 1 , wherein 
 the outer lid member is provided with an internal thread which can be screwed to an external thread of the neck of the tank.    
   
   
       3 . The lid according to  claim 1 , wherein 
 the outer lid member and the inner lid member define thereinbetween an annular coupling chamber which is filled with the medium.    
   
   
       4 . The lid according to  claim 1  wherein 
 projections and/or recesses are formed on the inner lid member and the outer lid member in the area of the coupling chamber.    
   
   
       5 . The lid according to  claim 1  wherein 
 the inner lid member and the outer lid member are provided with teeth projecting into the coupling chamber.