Fluidic pressure ratio control

Claim 2

A fluid control circuit in a gas turbine having a compressor for controlling the ratio between inlet and outlet pressure of the compressor, both of said pressures being variable, the circuit comprising a fluidic sensing means for detecting any error in said ratio, a first fluidic amplifying means arranged to amplify any such error to produce a control pressure, said fluidic sensing means including a reference pressure and a control pressure both of said pressures acting as control pressures for the first fluidic amplifying means, said reference pressure being obtained from a splitter, one of said variable pressures being supplied to one side of the splitter in the form of a variable pressure and arranged to pass through a first manually controlled variable area orifice, the other side of the splitter being vented to ambient pressure through a seCond variable area orifice, the first fluidic amplifying means having a variable feedback of the control pressure to the sensing means, the variation of the feedback pressure being dependent on the values of the variables, a second fluidic amplifying means having a variable power supply pressure dependent on one of said variables, an output pressure arranged to vary a control system upon which the values of the variables depend and a control signal which is the control signal generated by the first fluidic amplifying means, the second fluidic amplifying means being capable of operation in two modes, one in which the power supply pressure is greater than the control pressure and the output pressure is a function of the power supply pressure and the other in which the control pressure is greater than the power supply pressure and the output pressure is a function of the control pressure.

Claim 3

A circuit as claimed in claim 1 in which a variable area orifice is located in the feedback, the area of which is controlled as a function of, the first manually controlled variable area orifice in the splitter.

Claim 4

A circuit as claimed in claim 1 in which the splitter includes a further variable area orifice in parallel with the first manually controlled variable area orifice.

Claim 5

A circuit as claimed in claim 1 in which the power supply pressure to the second fluidic amplifying means is obtained from a splitter which is supplied with one of said variables in the form of a variable pressure via a fixed area orifice and is vented at the other side to a low pressure through a fixed orifice, the pressure supply to the amplifying means being through a variable area orifice.

Claim 6

A circuit as claimed in claim 1 in which the second fluid amplifying means also includes a vent via a variable area orifice to ambient pressure.

Claim 7

A circuit as claimed in claim 1 in which the first fluidic amplifying means comprises two or more proportional amplifiers arranged in series.

Claim 8

A circuit as claimed in claim 1 in which the second fluidic amplifying means comprises a vortex amplifier.

Claim 9

A circuit as claimed in claim 1 in which the control system upon which the values of the variables depend, comprises a fuel control system of a gas turbine engine.

Claim 10

A fluid control circuit in a gas turbine having a compressor for controlling the ratio between inlet and outlet pressure of the compressor, both of said pressures being variable, the circuit comprising fluidic sensing means for detecting any error in said ratio, a first fluidic amplifying means arranged to amplify any such error to produce a control pressure, said fluidic sensing means including a reference pressure and a control pressure, both of said pressures acting as control pressures for the first fluidic amplifying means and wherein said control pressure is obtained from a jet collector which is supplied with both of said inlet and outlet pressures in the form of variable pressures, the output pressure from the jet collector passing through a fixed orifice, said first fluidic amplifying means having a variable feedback of the control pressure to the sensing means, the variation of the feedback pressure being dependent on the values of the variables, a second fluidic amplifying means having a variable power supply pressure dependent on one of said variables, an output pressure arranged to vary a control system upon which the values of the variables depends and a control signal which is the control signal generated by the first fluidic amplifying means, the second fluidic amplifying means being capable of operation in two modes, one in which the power supply pressure is greater than the control pressure and the output pressure is a function of the power supply pressure and the other in which the control pressure is greater than the power supply pressure and the output pressure is a function of the control pressure.

Claim 11

A fluid control circuit in a gas turbine having a compressor for controlling the ratio between inlet and outlet pressure of the compressor, both of said pressures being variable, the circuit comprising fluidic sensing means for detecting any error in said ratio, a first fluidic amplifying means arranged to amplify any such error to produce a control pressure, said fluidic sensing means including a reference pressure and a control pressure, both of said pressures acting as control pressures for the first fluidic amplifying means and wherein said control pressure is obtained from a jet collector which is supplied with both of said inlet and outlet pressures in the form of variable pressures, the output pressure from the jet collector passing through a fixed orifice, said first fluidic amplifying means having a variable feedback of the control pressure to the sensing means, the variation of the feedback pressure being dependent on the values of the variables, a second fluidic amplifying means having a variable power supply pressure dependent on one of said variables, an output pressure arranged to vary a control system upon which the values of the variables depends and a control signal which is the control signal generated by the first fluidic amplifying means, the second fluidic amplifying means being capable of operation in two modes, one in which the power supply pressure is greater than the control pressure and the output pressure is a function of the power supply pressure and the other in which the control pressure is greater than the power supply pressure and the output pressure is a function of the control pressure.

Claim 12

A circuit as claimed in claim 9 in which the feedback pressure is connected to the control pressure generated by the jet coLlector downstream of the fixed area orifice.

Claim 13

A fluid control circuit in a gas turbine having a compressor for controlling the ratio between inlet and outlet pressure of the compressor, both of said pressures being variable, the circuit comprising a fluidic sensing means for detecting any error in said ratio, a first fluidic amplifying means arranged to amplify any such error to produce a control pressure, said fluidic sensing means including a reference pressure and a control pressure both of said pressures acting as control pressures for the first fluidic amplifying means, said reference pressure being obtained from a splitter, one of said variable pressures being supplied to one side of the splitter in the form of a variable pressure and arranged to pass through a first manually controlled variable area orifice, the other side of the splitter being vented to ambient pressure through a second variable area orifice, wherein the splitter includes a further variable area orifice in parallel with the first manually controlled variable area orifice and wherein a further solenoid operated orifice is located in parallel with said further variable area orifice and in communication with the reference pressure, the first fluidic amplifying means having a variable feedback of the control pressure to the sensing means, the variation of the feedback pressure being dependent on the values of the variables, a second fluidic amplifying means having a variable power supply pressure dependent on one of said variables, an output pressure arranged to vary a control system upon which the values of the variables depend and a control signal which is the control signal generated by the first fluidic amplifying means, the second fluidic amplifying means being capable of operation in two modes, one in which the power supply pressure is greater than the control pressure and the output pressure is a function of the power supply pressure and the other in which the control pressure is greater than the power supply pressure and the output pressure is a function of the control pressure.

Claim 14

A fluid control circuit in a gas turbine having a compressor for controlling the ratio between inlet and outlet pressure of the compressor, both of said pressures being variable, the circuit comprising a fluidic sensing means for detecting any error in said ratio, a first fluidic amplifying means arranged to amplify any such error to produce a control pressure, said fluidic sensing means including a reference pressure and a control pressure both of said pressures acting as control pressures for the first fluidic amplifying means, said reference pressure being obtained from a splitter, one of said variable pressures being supplied to one side of the splitter in the form of a variable pressure and arranged to pass through a first manually controlled variable area orifice, the other side of the splitter being vented to ambient pressure through a second variable area orifice, wherein the splitter includes a further variable area orifice in parallel with the first manually controlled variable area orifice and wherein a further solenoid operated orifice is located in parallel with said further variable area orifice and in communication with the reference pressure, the first fluidic amplifying means having a variable feedback of the control pressure to the sensing means, the variation of the feedback pressure being dependent on the values of the variables, a second fluidic amplifying means having a variable power supply pressure dependent on one of said variables, an output pressure arranged to vary a control system upon which the values of the variables depend and a control signal which is the control signal generated by the first fluidic amplifying means, the second fluidic amplifying means being capable of operation in two modes, one in which the power supply pressure is greater than the control pressure and the output pressure is a function of the power supply pressure and the other in which the control pressure is greater than the power supply pressure and the output pressure is a function of the control pressure.