RU2537665C1 - Fuel metering device of turbine jet - Google Patents

Abstract

FIELD: motors and pumps.

SUBSTANCE: fuel dosing device for turbine jet contains the first and second pulse-width modulators and the control unit connected to inputs of the first and second pulse-width modulators, the outputs of which through the respective electromagnetic valves are connected to the cavity of servo piston of the throttle needle and with the cavity of the constant pressure differential valve, and servo piston stem is connected with the throttle needle of variable section, at the expense of that the fuel supply camera is divided into two cavities, one of which is connected with the combustion chamber of the motor, and another one - with the fuel pump and constant pressure differential valve, and the control unit contains the series connected electronic regulator and logical device, connected with the inputs of the first and second pulse-width modulators, and provides the control switchover depending on the mismatch error value.

EFFECT: fuel saving at the expense of improvement of stability of static and response curves of the fuel metering device, improvement of precision of fuel metering in the turbine jet with simultaneous improvement of precision of the whole control system of the turbine jet.

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Description

The invention relates to aircraft instrumentation and can be used in automatic control systems (ATS) for dosing fuel into the combustion chamber of a gas turbine engine (GTE).

A known method of controlling the actuator of a fuel dispenser of a gas turbine engine and a system for its implementation (Patent RF №2285140, CL F02C 9/28, 2006), according to which the control signal and the position signal of the actuator of the dispenser are compared, this signal is compared with two threshold values of the dispenser , in both cases pulses are applied to reduce the error signal.

The disadvantage of this method is that due to the instability of static and dynamic characteristics due to the spread of parameter values due to natural processes taking place in the actuator, the choice of the threshold value of the error signal is quite difficult.

A device is known for automatic fuel metering in power plants of aircraft (RF Patent No. 2125656, class F02C 9/26, 1999), comprising a first bellows, first and second pneumatic dividers, first and second adjustable throttles of the nozzle-damper type, a servo piston with a throttle needle and a turbopump, characterized in that a second bellows, an air pressure alarm, an electronic controller, first and second electromechanical converters, a differential pressure valve and a constant pressure valve are additionally introduced, wherein the first and second bellows, the first and second pneumatic dividers are connected to an air pressure switch, which is connected to an electronic controller connected to the first and second electromechanical converters, the first of which is connected to the first adjustable throttle type nozzle-flapper and through it to the servo piston of the throttle needle and the second electromechanical converter is connected to a second adjustable throttle type nozzle-damper connected to a differential valve, which, in turn, is connected with a throttle needle, and through it - with the nozzles of the combustion chamber, the servo piston of the throttle needle and the differential pressure valve are connected through a constant pressure valve to the turbopump.

The disadvantage of this device is the incomplete accounting of dynamic processes occurring in the actuator, as a result of which a change in fuel consumption is possible.

Closest to the proposed is a device for dispensing fuel into the combustion chamber of a gas turbine engine (RF Patent No. 2059093, class F02C 9/26, 1996), comprising a servomotor that is connected to a throttle needle of variable cross section located in the cavity connected to the fuel pump and one from the cavities of the constant differential pressure valve, and the second cavity is connected to another cavity of the constant differential pressure valve, two electromagnetic valves, two pulse-width modulators and a control unit connected to the inputs irotno-width modulators whose outputs via respective electromagnetic valves connected to the respective cavities and throttle needle valve constant differential pressure. The operation of the device lies in the fact that the mismatch between the predetermined rotational speed of the rotor of the gas turbine engine and that obtained during the dosing process is measured, and based on the measured error, the dosage of fuel to the engine is adjusted.

A significant disadvantage of this device is the instability of its static and dynamic characteristics due to the natural variation of the parameters due to the insufficient accuracy of the manufacture of the fuel metering device, a change in the viscosity of the fuel with temperature, and also due to other reasons, such as aging, wear of materials, which together leads to insufficient fuel metering accuracy.

The objective of the proposed device is to save fuel by increasing the accuracy of fuel metering while increasing the accuracy of the automatic control system for the speed of a gas turbine engine.

The problem is solved by a device for dispensing fuel into a gas turbine engine containing a servomotor, first and second electromagnetic valves, first and second pulse-width modulators and a control unit connected to the inputs of the first and second pulse-width modulators, the outputs of which are connected to the cavity through the corresponding electromagnetic valves a servo piston of a throttle needle and with a cavity of a constant differential pressure valve, the servo piston rod being connected to a throttle needle of variable cross section, due to which the fuel supply chamber is divided into two cavities, one of which is connected to the combustion chamber of the engine, and the other to the fuel pump and constant pressure differential valve, in which, unlike the prototype, the control unit contains an electronic regulator connected in series and a logic device that is connected to inputs of the first and second pulse-width modulators.

The invention is illustrated by drawings, where figure 1 shows a schematic diagram of a device for dispensing fuel; figure 2 is a structural diagram of a system for automatically controlling the speed of a gas turbine engine; figure 3 - dependence of the mismatch between the specified fuel consumption of the gas turbine engine and the actual time.

The fuel metering device (FIG. 1) includes a servomotor 1 located in cavity A with a piston 2 and a rod 3 connected to a throttle needle 4 with a variable cross-section 5, the first and second solenoid valves 6 and 7, connected respectively to the first and second wide pulse modulators 8 and 9. The position of the second electromagnetic valve 7 maintains a predetermined pressure drop for the constant differential valve 10 with the piston 11, which interacts with the fuel supply chamber, which in turn is divided into cavities B and C, cavity B is connected to the combustion chamber of the engine, and cavity C is connected to the fuel pump and the constant differential pressure valve. The signals to the pulse-width modulators come from the control unit 12, which is part of the automatic speed control of the gas turbine engine. There are adjusting jets 13-16.

The automatic control system for the rotational speed of a gas turbine engine (FIG. 2) comprises a control unit 12, a comparison element 17, a fuel metering device 18, a gas turbine engine 19, the control unit 12 including an electronic controller 20 and a logic device 21.

The device operates as follows.

- рассогласование между заданным расходом топлива и полученным [Проблемы проектирования и развития систем автоматического управления и контроля ГТД / С.Т. Кусимов, Б.Г. Ильясов, В.И. Васильев и др. - М.: Машиностроение, 1999. - 609 с.]. Значение этой ошибки попадает на вход блока логического устройства 21, которое обеспечивает управление расходом топлива, путем переключения подачи управляющего сигнала между первым и вторым широтно-импульсными модуляторами в зависимости от величины рассогласования по расходу топлива. При этом широтно-импульсные модуляторы 8 и 9 в противофазе открывают (или закрывают) электромагнитные клапаны 6 и 7.The fuel consumption dosed into the engine is controlled by the signals of the control unit 12 depending on the size of the mismatch between the given rotational speed of the rotor of the gas turbine engine and the actual ξ _n = nn ⁰ (Fig. 2), this error enters the electronic controller 20, where according to known formulas are converted to fuel consumption error $${\xi }_{G_T}$$

- mismatch between the given fuel consumption and the received [Problems of design and development of automatic control and control systems of gas turbine engines / S.T. Kusimov, B.G. Ilyasov, V.I. Vasiliev et al. - M.: Mechanical Engineering, 1999. - 609 p.]. The value of this error goes to the input of the block of the logic device 21, which provides fuel consumption control by switching the supply of the control signal between the first and second pulse-width modulators, depending on the amount of mismatch in fuel consumption. In this case, pulse-width modulators 8 and 9 in antiphase open (or close) the electromagnetic valves 6 and 7.

, лежащей в зоне I в пределах от $${\xi }_{G_{T\max }}$$

до ξ₀ (фиг.3), управление выполняется по сигналу u₁ (фиг.2), то есть блок управления 12 через первый широтно-импульсный модулятор 8 и первый электромагнитный клапан 6 прикрывает соответствующий слив топлива из полости A, при этом давление в полости A серводвигателя 1 возрастает, и поршень 2 со штоком 3 и дроссельной иглой 4 перемещается вправо, уменьшая сечение 5 дроссельной иглы 4. Такое управление считается «грубым».In the logic device, fuel consumption is controlled as follows. Upon mismatch $${\xi }_{G_T}$$

lying in zone I ranging from $${\xi }_{G_{T\max }}$$

up to ξ ₀ (Fig. 3), the control is performed according to the signal u ₁ (Fig. 2), that is, the control unit 12 through the first pulse-width modulator 8 and the first electromagnetic valve 6 covers the corresponding drain of fuel from the cavity A, while the pressure in the cavity A of the servomotor 1 increases, and the piston 2 with the rod 3 and the throttle needle 4 moves to the right, reducing the cross section 5 of the throttle needle 4. This control is considered “rough”.

, лежащем в зоне II в пределах от ξ₀ до $${\xi }_{G_{T\min }}$$

(фиг.3), управление выполняется по сигналу u₂ (фиг.2), то есть блок управления 12 через второй широтно-импульсный модулятор 9 и второй электромагнитный клапан 7 прикрывает соответствующий слив топлива из полости С, при этом давление в полости В серводвигателя 1 уменьшается, и поршень 2 со штоком 3 и дроссельной иглой 4 перемещается вправо, уменьшая сечение 5 дроссельной иглы 4. Так производится точная «доводка» серводвигателя 1 с целью уменьшения рассогласования $${\xi }_{G_T}$$

.To control fuel mismatch $${\xi }_{G_T}$$

lying in zone II in the range from ξ ₀ to $${\xi }_{G_{T\min }}$$

(Fig. 3), control is performed according to the signal u ₂ (Fig. 2), that is, the control unit 12 through the second pulse-width modulator 9 and the second electromagnetic valve 7 covers the corresponding drain of fuel from the cavity C, while the pressure in the cavity B of the servomotor 1 decreases, and the piston 2 with the rod 3 and the throttle needle 4 moves to the right, reducing the cross section 5 of the throttle needle 4. This is the exact "finishing" of the servomotor 1 in order to reduce the mismatch $${\xi }_{G_T}$$

.

As a result, thanks to the proposed fuel metering device, the mismatch between the predetermined fuel consumption and the actual, as well as between the given rotor speed and the actual, is adjusted, thereby increasing the static and dynamic characteristics of the fuel metering device, increasing the accuracy of metering fuel into a gas turbine engine , which leads to fuel economy.

Thus, the proposed invention allows to reduce fuel consumption in a gas turbine engine and at the same time improve the accuracy of the automatic speed control system of a gas turbine engine.

Claims (1)

A fuel metering device for a gas turbine engine containing a servomotor, first and second electromagnetic valves, first and second pulse-width modulators and a control unit connected to the inputs of the first and second pulse-width modulators, the outputs of which are connected through the corresponding electromagnetic valves to the servo piston cavity of the throttle needle and with a cavity of the constant differential pressure valve, the servo piston rod being connected to a throttle needle of variable cross section, due to which the fuel supply chamber I am divided into two cavities, one of which is connected to the combustion chamber of the engine, and the other to the fuel pump and constant differential pressure valve, characterized in that the control unit contains a series-connected electronic controller and a logic device that is connected to the inputs of the first and second wide pulse modulators.

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