Patent ID: 11885162
Assignee: NAKANISHI INDUSTRIAL CO., LTD.
Field: Civil engineering (Other fields)
Classification: CPC E | IPC E

Claim 0:
1. A counter balance device for a sash window, comprising
a pipe extending along a window frame;
a spiral rod housed in the pipe, the spiral rod having a screw portion formed along a longitudinal direction and a lower end protruding from a lower end of the pipe;
a coupling rotatably disposed near the lower end of the pipe, the coupling having a slot through which the spiral rod is inserted and threadedly engaged;
a torsion spring which has a lower end secured to the coupling and an upper end secured near an upper end of the pipe and to which an initial spring force corresponding to the window's weight is applied by winding the torsion spring;
a slide block slidably disposed along the window frame and connected to the window; and
a rotation shaft rotatably mounted on the slide block,
wherein the lower end of the spiral rod is connected to the rotation shaft; and
wherein when a large repulsion force generated by the torsion spring acts on the rotation shaft via the spiral rod, a buffer spring having a spring force larger than the initial spring force acts to urge the rotation shaft in a direction reverse to the rotation direction of the spiral rod so that the rotation of the rotation shaft is tolerated.