| 摘要 |
A fuel control system for a staged combustion engine comprising, a fuel metering unit (11) including a fuel metering valve (16) having a fuel metering orifice the opening of which is varied to meter the flow of fuel through the metering valve (16) in use, a fuel staging unit (12) receiving fuel from the metering valve of the fuel metering unit and incorporating a staging valve (25) for dividing the flow of fuel from the fuel metering unit to pilot burner and main burner output lines (13,14), a connection (38;44) between a fuel pressure region (16a;32;33) of said fuel metering unit (11) and a port (37) of said staging valve (25), and, overthrust detection means causing said staging valve, in response to overthrust detection, to connect said port (37) of said staging valve to low pressure, thereby to drain fuel under pressure from said pressure zone of said fuel metering unit to low pressure to limit or reduce the fuel supplied from the fuel metering unit (11) to the fuel staging unit (12) and thus to the engine in use. <IMAGE> <IMAGE>
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