| 摘要 |
A pressure sensor (3) provides an opening signal when a minimum pressure is not attained and a closure signal when a max. pressure is exceeded beyond the cut-off valve (2). Such signals are passed to a control unit (4) which can either open or close the cut-off valve (4). The control unit (4) incorporates a time delay unit which retards the max. pressure signal for a specific time before it is fed further to the cut-off valve (2). However, it feeds the opening signal undelayed to the cut-off valve (2). The control probes and stores the times between two or more opening signals from the pressure sensor (3), and when it finds repeated occasions with the same time interval, it blocks the passage of opening signals to the cut-off valve. It also has a re-set device which causes the blocking of the opening signals to be removed. |
