| 摘要 |
The present invention relates to a control valve comprising a valve housing 1 having included therein a valve cylinder 4, in which a piston 25 is placed, displaceable between two positions. Further, the valve housing 1 is provided with an over-pressure channel 24 and an under-pressure channel 22 with connections. A throttled by-pass duct 29 is arranged to maintain equal pressures at both ends of the piston 25. Means 16, 19, 21 are arranged to be influenced by under-pressure in the under-pressure channel 22 for providing of a lowering of the pressure at one end of the piston 25 relative to the pressure at the other end of the piston 25. In this state, the throttled by-pass duct 29 is not able to equalize the pressure difference, which causes the piston 25 to be displaced to its other position. By this displacement, the piston 25 opens an over-pressure passageway from the over-pressure channel 24 to a connection 12, whereby the over-pressure at the connection 12 may be utilized as a signal. <IMAGE> |
