Hydraulic fluid control apparatus

摘要

The hydraulic fluid control apparatus has velocity control means and pressure control means. The apparatus has hydraulic fluid entry means for receiving hydraulic fluid and hydraulic fluid discharge means for supplying pressurized hydraulic fluid to hydraulic power means such as an hydraulically actuated oil well drill string power tong. The velocity control means is operatively associated with the hydraulic fluid entry means and serves to establish a desired predetermined velocity for the hydraulic fluid. The pressure control means is operatively associated with the hydraulic fluid discharge means for selectively limiting the exit pressure of the hydraulic fluid through the discharge means to predetermined levels. The pressure control means includes valve means adapted to divert pressurized fluid from the hydraulic fluid discharge means when the hydraulic fluid pressure exceeds predetermined levels. Valve control means are provided for selectively setting the position of the valve means to establish a said predetermined level. In another embodiment digital means are provided to receive an electrical signal from a transducer which emits such a signal proportional to the hydraulic fluid pressure. The signal emitted by the digital means is provided to a comparator which compares the signal with predetermined sets points and emits a signal to divert pressurized hydraulic fluid from the hydraulic fluid discharge means when the pressure therein exceeds predetermined levels.