| 摘要 |
1,211,741. Fluid-pressure servomotor systems. HOERBIGER VENTILWERKE A.G. Nov.21, 1967 [Nov.24, 1966], No.52857/67. Heading G3P. A multi-stage compressor, e.g. a piston-type, has stages I-IV and unloading is effected at a given receiver pressure by control unit R 1 which lifts the suction valves 7 of the first stage. The consequent fall in the delivery pressure of this stage is transmitted via line 5 both directly and through restrictor 19 to actuate the diaphragm of a leak-off relay R 2 . The latter causes valve 15 to open to by-pass air from the final stage to the line between stages I and II. When the control pressure on relay R 2 has equalized through restriction R 2 , the by-pass valve 15 closes. In this way, the time taken for the unloading sequence to affect the delivery to the receiver is reduced. In modifications, the first stage is unloaded by throttling the suction line or by-passing that stage and the final stage is unloaded by bleeding to atmosphere, by lifting the suction valves or by by-passing that stage only. The control may maintain a constant mass flow-rate. |
