| 摘要 |
1,129,937. Gas turbine engines; axial-flow compressors. ROLLS-ROYCE Ltd. April 11, 1967, No. 16614/67. Headings F1C, F1G and F1T. [Also in Division G3] A fluid-flow machine such as a gas turbine engine having a rotatable assembly mounted in a thrust bearing with freedom of limited axial movement comprises control means responsive to axial movement of the rotatable assembly or the bearing in response to a departure of the axial load on the bearing from a predetermined magnitude to control a pneumatic or hydraulic pressure applied to a substantially axially facing surface on the rotatable assembly or the bearing so as to compensate for the departure and maintain the axial load substantially constant, the control means including a variable restriction formed between a surface of the bearing and the fixed structure, a fluid pressure dependent on the restriction being used as a signal pressure in the control means representative of the axial position of the bearing. The by-pass or fan-type gas turbine engine shown in Fig. 1 comprises an H.P. compressor 102 driven by an H.P. turbine 104 through a shaft 103 mounted in ball thrust bearings 105, 106. Resilient woven metal spacer rings 115, 116, Fig.2, allow limited axial movement of the bearing outer races 107, 108, in response to changes in the axial load on the bearings, rotation of the outer races being prevented by teeth 114 engaging fixed teeth (not shown). Such axial movement changes the spacing between an orifice 118 and the adjacent surface of the outer race 108, causing a change in the rate of flow of air out of the orifice. This changes the air pressure P s in a passage 117 between a fixed restrictor 119 and the orifice 118. The change in the pressure P s is communicated via a conduit 134 to a servovalve 135 to produce a change in the pressure P o of compressed air communicated via a conduit 139 to a chamber 128 downstream of the turbine rotor disc 126. The resultant change of axial load applied by the pressure P o to the rotor disc 126 compensates for the initial change in the axial bearing load. The air used for the control is bled from the H.P. compressor 102 via a conduit 131, a filter 138 and a valve 136 which controls the input pressure P i to the servovalve 135 and to an air regulator 132. The pressure P r in a chamber 124 bounded by a cylindrical member 125 and a sealing ring 122 is applied via a probe line 137 to the regulator 132 to regulate the output pressure P r of the latter. Air at the regulated pressure P r is supplied via a line 133 and a drilling 120 to the fixed restrictor 119. Oil or other hydraulic fluid may be used to control the servovalve 135. |
