Closure counterbalance

Abstract

The closure counterbalance is for attachment as a strut between a movable closure which is hingedly fastened to a support structure. The counterbalance includes a pair of tubular members telescopingly connected together in sliding relationship. A compression coil spring within the members urges the members apart. A wooden rod is provided within the tubular members. The wooden rod fixed extends into the spring in sliding relationship therewith to support and guide the spring and prevent the spring from buckling against the inner surface of the tubular members.

What I claim as my invention is: 
     
       1. A counterbalance for a movable closure on a structure, comprising first and second tubular members telescopingly connected together in sliding relationship, each of said members having abutment structure at the outer end thereof, a compression coil spring within said members, the end of said spring pressing against said abutment structures thereby urging said tubular members apart, the outer diameter of said spring being less than the inner diameter of either of the tubular members, an elongated wooden rod within said tubular members in engagement at one end with the abutment structure of one of said members and extending into said spring in sliding contact therewith to guide same, said wooden rod terminating short of the abutment structure of the other of said tubular members when said tubular members are telescoped together. 
     
     
       2. A counterbalance as defined in claim 1, further characterized in the provision of a second compression coil spring of smaller diameter and shorter than said aforementioned coil spring positioned within said aforementioned coil spring (the) one end(s) of said .Iadd.second .Iaddend.spring pressing against one of .[.the inner (end) ends of.]. said wooden rod .Iadd.at its other end .Iaddend.and the abutment structure of the other of said tubular members and fixedly attached to the other .Iadd.of .Iaddend.said rod .Iadd.other end .Iaddend.and abutment structure when the tubular members are telescoped together to aid the aforementioned spring in urging said tubular members apart upon initial expansion of the counterbalance to cause unassisted initial movement of the movable closure prior to counterbalancing thereof by the counterbalance. 
     
     
       3. A counterbalance as defined in claim 2, further characterized in the provision of a cylindrical projection extending from the inner end of said wooden rod and of smaller diameter than said rod, said projection extending into the second spring in sliding relationship therewith to support and guide said second spring, and a boss on the abutment structure against which said second spring presses, said boss extending into said second spring to support said second spring. 
     
     
       4. A counterbalance as defined in claim 2, further characterized in the provision of a cylindrical projection on the abutment structure against which said second spring presses, said projection extending into the second spring in sliding relationship therewith to support and guide said second spring, and a boss on the inner end of said wooden rod against which said second spring presses, said boss extending into said second spring to support said second spring. 
     
     
       5. A counterbalance as defined in claim 3, further characterized in that said second spring is fixedly attached to said projection and is freely received on said boss. 
     
     
       6. A counterbalance as defined in claim 4, further characterized in that said second spring is fixedly attached to said projection and is freely received on said boss. 
     
     
       7. A counterbalance as defined in claim 1, further characterized in that the relative diameters of said tubular members are such as to provide an annular space therebetween, stop means on said tubular members for limiting relative outward movement thereof, said stop means comprising an inwardly extending projection on the outer of said members spaced from the inner end thereof, and an outwardly flared inner end on the inner tubular member engageable with said inwardly extending projection, said inwardly extending projection and said outwardly flared inner end being relatively long to provide energy absorbing means to compensate for overpull applied to the counterbalance. 
     
     
       8. A counterbalance as defined in claim 1, further characterized in the provision of bracket means extending from each of said abutment structures, said bracket means including a plastic grommet having a central opening for the reception of cylindrical fastening means for securement of the counterbalance to support structure, said central opening being enlarged at opposite ends of the grommet and having a gradually reduced diameter extending towards the center of the grommet to define an inner surface permitting limited pivoting of said fastening means. 
     
     
       9. A counterbalance as defined in claim 8, further characterized in that said grommet is detachably fastened to said bracket, said bracket having an opening therethrough, said bracket opening having an enlarged diameter at the ends thereof gradually decreasing towards the center thereof, said grommet having a matching external surface, said grommet having slot means at one end thereof permitting compression of said end for insertion into the opening of said bracket. .Iadd. 10. A counterbalance for a movable closure on a structure comprising first and second tubular members telescopingly connected together in sliding relationship, each of said members having abutment structure at the outer end thereof, a compression coil spring within said members, the end of said spring pressing against said abutment structures thereby urging said tubular members apart, the outer diameter of said spring being less than the inner diameter of either of the tubular members, an elongated rod within said tubular members in engagement at one end with the abutment structure of one of said members and extending into said spring in sliding contact therewith to guide same, said rod terminating short of the abutment structure of the other of said tubular members when said tubular members are telescoped together. .Iaddend. .Iadd. 11. A counterbalance as defined in claim 10, further characterized in that the relative diameters of said tubular members are such as to provide an annular space therebetween, stop means on said tubular members for limiting relative outward movement thereof, said stop means comprising an inwardly extending projection on the outer of said members spaced from the inner end thereof, and an outwardly flared inner end on the inner tubular member engageable with said inwardly extending projection, said inwardly extending projection and said outwardly flared inner end being relatively long to provide energy absorbing means to compensate for overpull applied to the counterbalance. .Iaddend..Iadd. 12. A counterbalance as defined in claim 10, further characterized in the provision of bracket means extending from each of said abutment structures, said bracket means including a plastic grommet having a central opening for the reception of cylindrical fastening means for securement of the counterbalance to support structure, said central opening being enlarged at opposite ends of the grommet and having a gradually reduced diameter extending towards the center of the grommet to define an inner surface permitting limited pivoting of said fastening means. .Iaddend. .Iadd. 13. A counterbalance as defined in claim 12, further characterized in that said grommet is detachably fastened to said bracket, said bracket having an opening therethrough, said bracket opening having an enlarged diameter at the ends thereof gradually decreasing towards the center thereof, said grommet having a matching external surface, said grommet having slot means at one end thereof permitting compression of said end for insertion into the opening of said bracket. .Iaddend.