| 摘要 |
1,199,060. Fastener driving tool. FASTENER CORP. 3 Nov., 1967 [19 Dec., 1966], No. 50050/67. Heading B4C. A pneumatically-actuated tool for driving fasteners, such as nails or staples, comprises a piston 26 movable in a cylinder 18 by means of compressed air fed from a reservoir 16 under the control of a valve means 20 and a control valve assembly 22 responsive only to joint actuation of trigger-and-safety control means 78, 80 in order to control the valve means 20. The control valve assembly 22 includes a valve piston 84 slidable in a cylinder 82 and provided with 0-rings 104, 106, 108, 110 defining chambers 112, 114, and 116. An exhaust valve 94 is slidable in the piston and cylinder 84, 82 and is formed with a head 94a for co-operation with a slot 92 in the piston. With the tool in the position shown in Fig. 3, air flows from the reservoir 16 through passages 118, 134, around the head 126 of a slidable valve member 122, a chamber 88 and passage 48 so as to maintain the valve means 20 closed .Upon pressing the nose of the tool against a workpiece so that the piston 84 is raised by the safety device 80 and then actuating the trigger 78 to open the valve 98, the pressurized air acting on the valve 20 is exhausted via a passage (90, Fig. 2) so that the valve 20 opens allowing air in the reservoir 16 to pass via a passage 46 to actuate the drive piston 26. At the end of the driving stroke, a valve 72 (more particularly described in Application No. 50050/67) in the drive piston allows air to pass through ports 62, a return reservoir 60, a passage 120 and a port 136 to thereby raise the valve member 122 so that the valve 20 is closed and the drive piston raised by the air in the reservoir 60. In a modification the piston 84 may be actuated by the trigger and the exhaust valve element 94 by the safety device. |
