Valve arrangement for the working cylinder of a pneumatically operated stapler

Claim 1

A valve arrangement for the working cylinder of a pneumatically operated tool, comprising: a tool housing; a working cylinder mounted in said tool housing; a piston reciprocable in said working cylinder; a channel formed in said housing through which compressed air is passed to said cylinder; at least one annular valve chamber formed in said housing operatively adjacent said channel; at least one elastic, radially deformable ring arranged in said channel, said at least one ring having outer rims which constitute control pressure areas, an auxiliary valve means for operatively controlling said control pressure areas; said at least one ring having inner rims constituting closing members for said air channel, said housing being formed with an outlet opening communicating with the interior of said working cylinder and formed with an annular groove underneath said working cylinder, said annular groove communicating with said outlet opening; an additional elastic, radially deformable ring mounted underneath said working cylinder in said annular groove of said tool housing; said additional elastic ring having an outer rim constituting a control pressure surface and an inner rim serving as a closing means for said outlet opening; a second channel formed in said housing and communicating with said annular groove; and means for communicating a means containing a controlled pressure medium into said second channel, said outer rim of said additional elastic ring communicating via said second channel with said controlled pressure medium.