Counterbalance apparatus with transverse pneumatic spring and bellcrank linkage with improved pneumatic spring structure and method of operation

Abstract From the Canadian patent

A transversely mounted single pneumatic spring, and dual, bell crank and idler link assembly providing a compact counterbalance for hinged closures such as automobile trunk lids. In an automobile trunk installation the assembly is installed, with the spring in lateral disposition in the forward upper portion of the trunk, thus being effectively concealed. Alternative pneumatic spring enhancements e.g. a multi-output, force feature and a pressure decay compensation feature may be incorporated in the spring unit to enhance opening of the lid and to improve life expectancy of the pneumatic spring by minimizing and effectively negating pressure loss due to leakage of gas past the shaft seal. …