| 摘要 |
<p>862,258. Fluid-pressure servomotor-control systems. WESTINGHOUSE ELECTRIC CORPORATION. April 27, 1959 [April 30, 1958], No. 14224/59. Class 135. A governor for a prime mover such as a steam turbine 10 having admission valves 12 controlled by a servomotor 14 has a prime mover driven hydraulic pump 22 feeding the servomotor 14 through a restriction 35, and a leak-off valve 30 controlling escape of fluid from the servomotor under the control of speed and acceleration means including a reverse flow governor pump 17 fed through a restriction 21 by the pump 22 and producing a pressure which is conveyed through a conduit 27 to a chamber containing a bellows 26 which, through a lever 31 loaded by a spring 32, controls the valve 30. The arrangement is such that increase of pressure in the conduit 27 due to an increase of speed of the prime mover results in opening of the valve 30 with consequent lowering of the pressure in a conduit 29, the servomotor 14 being arranged to close the admission valve in response to reduction of pressure. The valve 30 can also be operated by an acceleration responsive diaphragm 43 subject on its upper surface to pressure in a chamber 50 connected directly to the conduit 29 and on its lower surface to pressure in a chamber 52 connected with the conduit 29 by a first passage comprising a restriction 60, a duct 57, a variable volume chamber 53 containing a bellows 54, and a check valve 59, and by a second passage comprising the restriction 60, a duet 78, a restriction 76 and a duct 72. In response to a rapid acceleration of the prime mover the pressure in the chamber 50 falls at a sufficiently greater rate than that in the chamber 52 to cause the diaphragm 43 to rise to enable the valve 30 to release pressure from the conduit 29 at the still greater rate to cause a rapid closure of the turbine admission valves. Fluid under pressure will then escape from the chambers 52, 53 under the control of the restriction 60 until the bellows 54 has expanded whereupon the check valve 59 will close and the chamber 52 will continue to exhaust through the duct 72 and restrictions 76, 60 until the pressures on either side of the diaphragm are equalized. The downward bias on the diaphragm assembly due to the weight thereof determines the value of acceleration at which the diaphragm becomes effective. This bias may be substituted by a spring should the arrangement be such that the diaphragm assembly is mounted with its axis other than vertical.</p> |
