RU2532943C1 - Onboard system for fuel control and measurement with compensation for fuel temperature - Google Patents

Abstract

FIELD: aircraft engineering.

SUBSTANCE: this system comprises fuel parameter transducers fitted in aircraft fuel tanks: Fuel level and dielectric constant, fuel upper and lower level indicators, onboard computer with left and right control modules, control channels and memory cells on fuel tank geometry, left and right fuel age modules, comparator and balance adjuster. System onboard computer incorporates inputs to receive extra data from fuel flow rate transducers and aircraft roll and pitch transducers.

EFFECT: higher accuracy, validity and efficiency of measurement fuel mass store, fuel reserve supply and control over aircraft balance at standard and emergent conditions of system operation.

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Description

The present invention relates to aircraft instrumentation and can be used to measure the mass fuel supply on an airplane and control the distribution of fuel in the fuel tanks of an airplane.

Known on-board fuel measuring system designed to measure the fuel supply on board the aircraft [Patent of the Russian Federation No. 2156444, IPC G01F 23/26, publ. 2000]. It contains fuel level sensors installed in the fuel tanks, an on-board computer, a fuel temperature sensor installed in one of the fuel tanks, a comparison device and an indicator. The mass fuel supply in this system is determined by correcting the volume of fuel in the on-board computer from the measured value of the fuel temperature in one of the fuel tanks, and the volume of fuel is determined in the on-board computer based on information received from the fuel level sensors.

The disadvantages of the known system are the presence of a methodological error in determining the mass supply of fuel caused by the dispersion of fuel temperatures in different fuel tanks, as well as the inability to detect fuel imbalance in symmetrically located fuel tanks of opposite sides of the aircraft.

These disadvantages are partially absent in the known on-board fuel metering system with temperature compensation [Patent for the invention of the Russian Federation No. 2189926, IPC 7 B64D 37/00, 37/14, G01F 23/26, publ. 2002].

The composition of this system, designed to measure the mass supply and unbalance of fuel on board an aircraft, includes an on-board computer, a comparison device, an indicator, as well as fuel level indicators and fuel level sensors installed in the fuel tanks: level and temperature.

The known system is characterized by a sufficiently low error in measuring the mass fuel supply on board the aircraft, which is achieved by installing fuel temperature sensors in all stationary fuel tanks of the aircraft.

However, in the known system, balancing the fuel on board the aircraft is carried out with a significant methodological error, which leads to a fuel imbalance that violates the lateral alignment of the aircraft in flight, since the fuel masses in the right and left symmetrically located fuel tanks of the aircraft can differ significantly from each other.

The specified methodological error is caused by the fact that in the known system the current values of the fuel mass in each of the fuel tanks are determined by subtracting the mass of fuel consumed by the aircraft engines from the fuel tanks in flight from the mass of fuel poured into these tanks when refueling the aircraft with fuel on the ground.

Since both of these values: the mass of spent fuel and the mass of refueling, in a particular fuel tank are calculated in the known system with the error of integration of the instantaneous fuel consumption over the flight time, as well as with the error of measuring the temperature and dielectric constant of the fuel in the said tank, the system arises and increases with integration over the flight time, the error in determining the actual mass of fuel in the fuel tank, which leads to an increase in imbalance fuel and violation of the transverse alignment of the aircraft fuel.

This drawback is partially eliminated in the closest to the proposed invention in terms of technical nature and the achieved technical result and adopted as the closest analogue (prototype) of the fuel and flow meter system of the aircraft with temperature compensation [Patent of the Russian Federation No. 2327611, IPC G01F 23/26, B64D 37/14 , B64D 37/00, publ. 2008], which includes an on-board computer that contains inputs for receiving information from fuel consumption sensors, a comparison device, a balancing device, a fueling device, an indicator, as well as low fuel level warning devices installed in the fuel tanks and fuel parameter sensors connected to the on-board computer: level and temperature, moreover, the on-board computer is connected by an information communication line to a comparison device and contains an output for connecting using an information line to an external system moms of the aircraft, and the balancing device is equipped with outputs for transmitting control signals for pumping fuel.

The known system allows with sufficient accuracy to measure the mass of fuel in each of the fuel tanks of the aircraft and on the aircraft as a whole, to determine the amount of reserve fuel remaining and to control the balance of the aircraft by fuel in normal operation, i.e. in the absence of failures of system elements or significant changes in external conditions.

However, with a significant change in flight conditions, for example, caused by spatial evolutions of the aircraft, or significant deviations of the refueling fuel parameters from the nominal ones, for example, caused by the deviation of the actual density of the refueling fuel from the nominal value, as well as in case of failures of elements or connections of the system, the known system does not accurately measure a massive fuel supply, and also not sufficiently reliably generates a signal about the reserve fuel balance.

It is also not accurate enough, reliably and effectively known system controls the lateral balancing of the aircraft for fuel, especially at the final stage of flight, as well as in emergency mode. Fuel balancing is necessary to eliminate the fuel imbalance between symmetrically located fuel tanks of the opposite sides of the aircraft, leading to a violation of the lateral alignment of the aircraft. To control the balancing in a known system, control signals are formed for pumping fuel from fuel tanks with a fuel amount greater than the nominal one into symmetrically located fuel tanks with a fuel amount less than the nominal one.

The purpose of balancing fuel transfer is to restore the nominal lateral alignment of the aircraft by leveling the mass of fuel on its port and starboard sides. The formation of fuel transfer control signals is made based on the comparison in the device for comparing the values of the remaining fuel in the left and right symmetrically located fuel tanks of the aircraft. The fuel supply in the fuel tank is determined by subtracting the mass of fuel consumed from this tank in flight from the mass of fuel charged to it on the ground. However, when determining the fuel imbalance in the known system, the mass of fuel consumed from the fuel tanks is determined from the information on the fuel consumption from these tanks. Since the fuel mass consumed in flight is calculated in a known system by integrating the fuel consumption over the flight time, the integration error increases with the flight time and can reach a significant value by the middle of the flight.

Therefore, the method used in the known system for determining the imbalance from the information on the volumetric fuel consumption contains a significant methodological measurement error that increases with the flight time, which does not allow the known system to effectively control the lateral alignment of the aircraft by fuel starting from the middle of the flight.

In addition, in the known system, the fuel imbalance in general cannot be reliably determined in case of failure of any of the fuel flow sensors.

In addition, in the known system, the mass of fuel in a fuel tank containing sensors of fuel parameters: level and temperature, in an abnormal mode of operation, i.e. in case of failure of any of the above sensors, especially in case of failure of the fuel level sensors

In addition, in the known system, a reliable signal about the reserve fuel balance can be generated only in the normal mode of operation in the absence of failures and significant changes in external conditions.

This is because the signal on the reserve fuel remaining is generated in the known system only by the low fuel level warning device. Therefore, in an abnormal mode of operation in case of failure of the aforementioned signaling device or with a significant change in the external conditions of its operation, for example, during spatial evolutions of an aircraft, a signal about the reserve balance either cannot be generated at all or is formed with a significant error.

The objective of the invention and its technical result is to increase the accuracy and reliability of the system, both in regular and emergency modes.

The specified task is solved:

firstly, by increasing the accuracy of measuring the mass of fuel by metrological integration of information about the level, permittivity and density of the fuel, the angles of the spatial position of its free surface and the geometry of the fuel tanks,

secondly, due to the metrological parry of the failures of the fuel parameter sensors by using information from the corresponding serviceable sensor located on the opposite side of the aircraft symmetrically refused,

thirdly, due to the majority formation of a signal about the reserve fuel balance using three physically dissimilar sources of measurement information.

To solve this problem, an on-board fuel control system with fuel temperature compensation, containing an on-board calculator, a comparison device, a balancing device, a refueling device, an indicator and low fuel level warning devices installed in the fuel tanks, as well as sensors installed in the fuel tanks and connected to the on-board computer fuel parameters: level and temperature, moreover, the on-board computer contains inputs for connecting to fuel consumption sensors, an output for connecting with and information line to external aircraft systems and is connected via an information line to a comparison device, and the balancing device is equipped with outputs for transmitting fuel transfer control signals, supplemented with new elements and connections.

The proposed system differs from the prototype in that it has additionally introduced left and right control modules, each of which is equipped with primary and backup inputs, right and left fuel gauge modules, a control panel, a fuel density adjuster, fuel level high level indicators installed in the fuel tanks, as well as the right and left control channels and the right and left memory cells, the number of control channels and the number of memory cells being equal, each, to the number of fuel tanks, fuel density adjuster, lock device Set and display part of the remote control, the right and left memory cell included in the right and left control modules respectively, and the control modules and control channels included in the onboard computer.

In addition, the comparison device is equipped with an additional output intended for connecting to the corresponding input of the aircraft's external systems, the on-board computer is supplemented with an input intended for connecting using the communication line to the aircraft’s roll and pitch angle sensors, and fuel temperature sensors are installed in the fuel tanks at the height of the signaling devices lower fuel level.

Elements of the proposed system have the following connections and connections.

The fuel parameter sensors are connected to the on-board computer through the fuel gauge modules, said sensors installed in the specific fuel tank being connected to the on-board computer through the fuel gauge module corresponding to the tank. In this case, the outputs of each of the left fuel gauge modules are connected using the corresponding communication lines to the main input of the left control module and to the redundant input of the right control module, and the outputs of each of the right fuel gauge modules are connected using the corresponding information lines to the main input of the right control module and with redundant input of the left control module.

The left and right control modules are interconnected by a two-way communication line, and the output of each of these modules is connected using the corresponding information line to the output of the on-board computer connected to the comparison device, the output of each of the left control channels is connected by a corresponding two-way communication line with one from the inputs of the left control module, and the output of each of the right control channels is connected by a corresponding two-way information line ides with one of the inputs of the right control module; the control panel is connected to the on-board computer with a two-way communication line, and the output of the refueling device and the output of the fuel density adjuster are connected, each, to one of the indicator inputs.

The fuel parameter sensors are connected to the on-board computer via the corresponding fuel gauge modules as follows: the outputs of each of the fuel level sensors installed in a particular fuel tank are connected to each other and connected to one of the inputs of the fuel gauge module corresponding to the mentioned tank, and the output of the sensor installed in the same fuel tank fuel temperature is connected to another input of said module. The output of each of the lower fuel level alarms is connected to one of the corresponding inputs of the on-board computer, and the output of the comparison device is connected to the input of the balancing device, using the information line, whose outputs are used to transmit control signals for pumping fuel to external aircraft systems.

The device and operation of the proposed system are illustrated by the Figure.

The Figure shows a functional diagram of the proposed system for the case when the number of fuel tanks n = 4. Since the number of inputs of the fuel gauge modules, the number of control channels and the number of memory cells of the proposed system are proportional to the number of fuel tanks (or fuel compartments) with fuel parameters sensors and fuel level indicators installed in them, only the number of fuel tanks (or fuel compartments) changes the number of the mentioned elements and inputs, however, the structure of the relationships between the elements of the system remains unchanged. Therefore, the essence of the proposed invention does not depend on the number of fuel tanks (or fuel compartments), provided that this number is even, and the left and right fuel tanks are symmetrical.

The following notation is introduced in the Figure:

1 - fuel level sensor, 2 - fuel temperature sensor, 3 - low fuel level indicator, 4 - bulkhead, 5 - first left fuel tank, 6 - second left fuel tank, 7 - first right fuel tank, 8 - second right fuel tank 9 - the first left fuel gauge module, 10 - the second left fuel gauge module, 11 - the first right fuel gauge module, 12 - the second right fuel gauge module, 13 - the left control module, 14 - the right control module, 15 - the on-board computer, 16 - the main input control module, 17 - redundant input of the control module, 18 - first le vaya memory cell, 19 - the second left memory cell, 20 - the first right memory cell, 21 - the second right memory cell, 22 - the first left control channel, 23 - the second left control channel, 24 - the first right control channel, 25 - the second right control channel, 26 — a comparison device, 27 — a balancing device, 28 — a control panel, 29 — a refueling device, 30 — an indicator, 31 — a fuel density adjuster, 32 — an aircraft roll and pitch angle sensor, 33 — a fuel consumption sensor, 34 — external aircraft systems.

The sensors of the fuel level 1 and fuel temperature 2, as well as the lower fuel level sensors 3 are installed in the fuel compartments, which with the help of bulkheads 4 can be allocated in the first and second left fuel tanks 5 and 6, respectively, and in the first and second right fuel tanks 7 and 8, respectively.

The outputs of the fuel level sensors 1, installed in the first left fuel tank 5, are interconnected and connected to one of the inputs of the first left module of the fuel meter 9.

In a similar way, fuel level sensors 1 of the second left fuel tank 6 are connected to each other and connected to one of the inputs of the second left fuel gauge module 10, fuel level sensors 1 are connected to one of the inputs of the first right fuel gauge module 11 of the first right fuel tank 7, are interconnected and connected to one of the inputs of the second right module of the fuel gauge 12 fuel level sensors 1 of the second right fuel tank 8.

In the same way, the fuel temperature sensor 2, installed in a particular fuel tank 5, 6, 7, 8, is connected to another input of the fuel gauge module 9, 10, 11, 12 corresponding to the said fuel tank.

The control modules 13, 14 are part of the on-board computer 15. The output of each of the lower fuel level sensors 3 is connected to the corresponding input of the on-board computer 15. One of the outputs of the first left fuel meter module 9 is connected by a communication line to the main input 16 of the left control module 13, and the other output of said fuel gauge module is connected by a communication line to the backup input 17 of the right control module 14; in the same way, one of the outputs of the second left fuel gauge module 10 is connected by the communication line to the main input 16 of the left control module 13, and the other output of the mentioned fuel gauge module is connected by the communication line with the backup input 17 of the right control module 14.

Similarly, one of the outputs of the first right module of the fuel gauge 11 is connected by a communication line to the main input 16 of the right control module 14, and the other output of the said module 11 is connected by a communication line to the backup input 17 of the left control module 13; in the same way, one of the outputs of the second right module of the fuel gauge 12 is connected by the communication line to the main input 16 of the right control module 14, and the other output of the mentioned module 12 is connected by the information line of communication with the backup input 17 of the left control module 13.

The left control module 13 contains the first and second left memory cells 18 and 19, respectively, designed to store information about the geometry of the first and second left fuel tanks 5 and 6, respectively, and the right control module 14 is provided with the first and second right memory cells 20 and 21, respectively. designed to store information about the geometry of the first and second right fuel tanks 7 and 8, respectively. The left and right control modules 13 and 14 are interconnected by a two-way communication line, in addition, the left control module 13 is connected by a two-way communication line with the first left control channel 22 and a two-way information line with the second left control channel 22; in the same way, the right control module 14 is connected by a two-way communication line with the first right control channel 24 and a two-way information line with the second right control channel 25. All of the control channels mentioned are part of the on-board computer 15.

The output of the left control module 13 and the output of the right control module 14 are connected, each, using the corresponding information line to the output of the on-board computer 15, connected via the information line to the input of the comparison device 26, connected via the information line to the input of the balancing device 27 .

The on-board computer 15 is connected by a two-way communication line with the control panel 27, which includes a refueling device 29, an indicator 30 and a fuel density adjuster 31, the output of the refueling device 29 and the output of the fuel density adjuster 31 are each connected to a corresponding input of the indicator 30. The roll angle and pitch angle sensor of the aircraft 32, interacting with the proposed system, is connected by an information line to the corresponding input of the on-board computer 15. Each of the fuel flow sensors 33, interacts uyuschih with the proposed system is also connected to the corresponding input onboard computer 15, one output of which is connected via the information link with external systems corresponding input plane 34, which include information system and power unit. An additional output of the comparison device 26, as well as each of the outputs of the balancing device 27, is connected to one of the inputs of the external systems of the aircraft 34.

At various stages of pre-flight preparation and flight of the aircraft, the proposed system performs the following functions.

In pre-flight preparation, the proposed system

- controls the fueling of each fuel tank 5, 6, 7, 8 of the aircraft.

In flight proposed system

- measures the mass fuel supply in the fuel tanks 5, 6, 7, 8 and on the plane as a whole both in the normal operation mode (in the absence of failures) and in the emergency mode (in the presence of failures);

- manages fuel balancing in normal and emergency modes;

- generates a signal about the reserve fuel balance in the normal and emergency modes.

- During the pre-flight preparation of the aircraft, the fueling of the fuel tanks 5, 6, 7, 8 is controlled from the control panel 27.

Using the refueling device 29, which is part of the above-mentioned console, the operator sets and displays on the indicator 30 the set value of the fuel mass m _n in the nth fuel tank, as well as the total fuel mass on the plane m (mass fuel supply) equal to the sum of the fuel mass tucked into each of the fuel tanks 5, 6, 7, 8 (here n is the number of the fuel tank; according to the numbering adopted in the Figure, n = 5, 6, 7, 8).

In addition, using the fuel density adjuster 31, the operator sets and displays on the indicator 30 the passport density value of the refueling fuel ρ _о . Data on the given values of the fuel mass m _n in each of the fuel tanks 5, 6, 7, 8, on the total fuel mass on the plane m and on the passport value of the fuel density ρ _о are transmitted via a two-way information line from the control panel 28 to the on-board computer 15 .

As the fuel tanks 5, 6, 7, 8 are filled with fuel, the fuel level sensors 1 installed in each of these tanks generate analog measuring information about the current fuel level value h (τ) _n in the nth fuel tank (here τ is the current time value). In this case, the fuel temperature sensor 2 installed in the same fuel tank generates analog corrective information about the temperature t _{n of the} fuel in the nth fuel tank 5, 6, 7, 8.

The measurement and correction information generated by the sensors 1 and 2 of the fuel parameters installed in the nth fuel tank are fed to the corresponding inputs of one of the fuel gauge modules 9, 10, 11, 12 corresponding to the given fuel tank, for example, information from the output of each of the sensors 1 and 2 installed in the first left fuel tank 5, is fed to the corresponding inputs of the first left module of the fuel gauge 9.

In each of the fuel gauge modules 9, 10, 11, 12, the received analog information is normalized, converted to digital form, and transmitted via information lines from the respective outputs of each of these modules to the corresponding inputs of the control modules 13, 14: from the outputs of the first left fuel gauge module 9 - to the main input 16 of the left control module 13 and to the backup input 17 of the right control module 14, from the outputs of the second left module of the fuel gauge 10 - to the main input 16 of the left control module 13 and to the backup input 17 of the right mode I control 14, from the outputs of the first right module of the fuel gauge 11 to the main input 16 of the right control module 14 and to the backup input 17 of the left control module 13, and from the outputs of the second right module of the fuel gauge 12 to the main input 16 of the right control module 14 and to the backup input 17 of the left control module 13.

Moreover, in the normal mode of operation of the system in the control modules 13, 14, only that information is used that arrives at their main inputs 16, and in non-standard mode, only that information is received at the main input of the control module corresponding to the board that does not contain failed level sensors fuel 1, and to the backup input 17 of the control module corresponding to the board containing at least one failed fuel level sensor 1.

According to the information about the current value of the fuel level h (τ) _n in the nth fuel tank 5, 6, 7, 8 in the control module 13, 14 corresponding to the side of this tank, using the geometry data of the nth fuel tank requested from memory cells 18, 19, 20, 21 corresponding to the aforementioned tank, and information on the angles γ and β of the spatial evolution of the aircraft received by the on-board computer 15 from the roll angle and pitch sensor of the aircraft 32, the current value of the fuel volume in the nth fuel tank is calculated:

$$V{\left(\tau \right)}_n=F\left[h{\left(\tau \right)}_n;f{\left(h,\gamma ,\beta \right)}_n\right],\left(\mathrm{one}\right)$$

where F is an algorithmic dependence linking the current value of the fuel volume in the nth fuel tank with the current value of the fuel level in this tank depending on the geometry of the nth fuel tank and roll angles γ and pitch β of the aircraft;

h (τ) _n is the current value of the fuel level in the nth fuel tank;

f (h, γ, β) _n is an algorithmic function connecting the geometry of the flat horizontal section of the nth fuel tank with the coordinate of this section equal to the value of the fuel level h for several values of the angle of heel γ and pitch β of the aircraft, for example, at nominal, maximum and minimum values. When refueling an airplane with fuel, the angles γ and β are taken equal to the angles of the airplane's parking position, γ _о and β _о, which are entered into the memory of the on-board computer 15 when the work program is loaded. It should be noted that the volume of fuel in the tank actually depends on the angles γ _t , β _{t of the} spatial position of the free surface of the fuel. However, since the values of the mentioned angles can be considered equal to the angles γ, β of the roll and pitch of the aircraft:

γ _t ≈γ, β _t ≈β,

then the angles γ and β are used as arguments of expression (2).

The values of the algorithmic function f (h, γ, β) _n for the first and second left fuel tanks 5 and 6 are stored in the memory cells of the left control module 13: in the first and second left memory cells 18 and 19, respectively. Similarly, the values of the above-mentioned functions for the first and second right fuel tanks 7 and 8 are stored in the first and second right memory cells 20 and 21, respectively, of the right control module 14.

Because mass m is related to volume V and density ρ by the well-known formula m = Vρ, then, based on the current values of fuel volumes V (τ) _n calculated by formula (1) in each of the fuel tanks 5, 6, 7, 8, in the control modules 13, 14, the current values of the fuel mass in each of these tanks are determined in accordance with the expression:

$$m{\left(\tau \right)}_n=F\left[h{\left(\tau \right)}_n;f{\left(h,\gamma ,\beta \right)}_n\right]{\rho }_o\left(\mathrm{one}+\alpha t_n\right),\left(2\right)$$

where ρ _about - passport value of the density of the fuel;

α is the temperature coefficient of fuel;

t _n - fuel temperature in the nth fuel tank.

The remaining notation is explained when considering the expression (1).

The passport value of the fuel density ρ _о used in formula (2) is input to the on-board computer 15 via a two-way information line from the output of the control panel 28, and the temperature coefficient of the fuel density α is entered into the memory of the on-board computer 15 when the work program is loaded.

When the n-th fuel tank reaches the equality of the specified value of the fuel mass m _{n the} current value of the fuel mass m (τ) _n

$$m_n=m{\left(\tau \right)}_n\left(3\right)$$

in the on-board computer 15 is generated and from its output on the communication line is transmitted to the external systems of the aircraft 34 command to stop the supply of fuel to the nth fuel tank, and refueling of this tank with fuel is stopped. When equality (3) is fulfilled for all n = 5, 6, 7, 8, the fueling of the aircraft ends.

- In flight, the proposed system measures the mass of fuel in each of the fuel tanks 5, 6, 7, 8 and on the plane as a whole by metrological integration of the fuel measurement information generated by several independent, physically diverse sources of information.

Moreover, the procedure described above for measuring current values of the fuel level, fuel volume and fuel mass in each of the fuel tanks 5, 6, 7, 8 and on the plane as a whole is stored and algorithmically corresponds to expressions (1) and (2).

During the flight, fuel refueled on the ground is consumed by aircraft engines from fuel tanks 5, 6, 7, 8 and its amount is continuously reduced. As a result, the current values of the fuel level h (τ) _n in each of the fuel tanks 5, 6, 7, 8 decrease, and the current values of the fuel temperature t _n in these tanks change due to their heat exchange with the surrounding air and the current values of the angle of heel γ and β pitch of the aircraft due to the spatial evolution of the aircraft. This leads to a change in current fuel information generated by fuel level sensors 1, fuel temperature sensors 2, as well as a roll angle sensor γ and pitch β of aircraft 32, which is fed to the corresponding inputs of the fuel gauge modules 9, 10, 11, 12, as well as the corresponding input of the on-board computer 15.

From the outputs of the above-mentioned modules, current information is transmitted via communication lines to the corresponding inputs of the control modules 13, 14, in which, in accordance with (2), the current values of the fuel mass m (τ) _n varying in flight in each of the fuel tanks 5, 6 are calculated 7, 8 and on the plane as a whole.

If during the flight of an aircraft one of the sensors of fuel parameters 1, 2 fails, which generates analog information about the fuel in the fuel tanks 5, 6, 7, 8, the proposed system continues to operate in an emergency mode while maintaining the accuracy and reliability of measurements. For this purpose, in an emergency mode in the control modules 13, 14, metrological parry of the information of the failed sensors is performed. Since the parametric failure of the fuel sensor, which consists in a smooth change in its transfer function, is unlikely, in the control modules 13, 14 only cases of catastrophic failures are controlled: a short circuit of the sensor or a break in its communication line.

Since the sensor does not function in the event of a catastrophic failure, there is no signal at the output of the failed fuel temperature sensor 2. The absence of a signal at the output of the sensor of a working system is a reliable diagnostic sign of its failure. If a sensor 2 failure is detected in one of the control modules 13, 14 corresponding to the board of the mentioned sensor, a command is generated to switch the output of the failed sensor to the output of the sensor of the same name located on the opposite side of the aircraft symmetrically to the failed one. Moreover, the fuel parameter information generated by the failed sensor 2 is replaced by the corresponding information from the symmetrically located sensor 2, and the proposed system continues to work without a significant change in the measurement error.

However, a catastrophic failure of the fuel level sensor 1 cannot be detected by the described method by the absence of an output signal, because the fuel level sensors 1 of the proposed system located in each of the fuel tanks 5, 6, 7, 8 are integrated within each fuel tank into a group of sensors connected in parallel.

Although in case of failure of one or several fuel level sensors 1 of this group, the signal at its output changes stepwise, it nevertheless preserves the final value, and the fact of failure cannot be established by the absence of a signal at the output of the group of fuel level sensors 1. Therefore, in the proposed the system failure of the fuel level sensor 1 is established by the method of tolerance control by periodically comparing the parameters of the monitored group of level 1 sensors with the parameters of one of the control channels 22, 23, 24, 25 corresponding to that mentioned oh group.

Each of the control channels 22, 23, 24, 25, which are part of the on-board computer 15, contains in its memory the tolerance values of the monitored parameters of the corresponding group of fuel level sensors 1: control channel 22 contains the tolerance values of the group of fuel level sensors 1 of the fuel tank 5, control channel 23 - groups of fuel level sensors 1 of the fuel tank 6, control channel 24 - groups of fuel level sensors 1 of the fuel tank 7, and control channel 25 - groups of fuel level sensors 1 of the fuel tank 8.

Failure of one of the sensors in the group leads to an abrupt change in its monitored parameters that go beyond tolerance values. During tolerance control of the parameters of the group containing the failed fuel level sensor 1, its parameters are compared with the parameters of the corresponding control channel 22, 23, 24, 25 in the corresponding control module 13, 14. As a result of the comparison, the fact of non-compliance with the tolerance indicating exit failure of one or more fuel level sensors 1 in the controlled group and a switching command is generated.

In accordance with the switching command, information from the rejected group of fuel level sensors 1 is replaced by information from a symmetrically located group of fuel level sensors 1 of the opposite side.

For example, if a failure of one of the fuel level sensors 1 installed in the first left fuel tank 5 is detected, a switching command is generated and transmitted via the two-way information line to the right control module 14 in the left control unit 13, according to which the information is interrupted, transmitted by the rejected group of sensors 1 to the corresponding input of the first left fuel meter module 9 and, further, from the outputs of the latter, to the main input 16 of the left control module 13 and a redundant input 17 of the right mode For control 14. Instead of the interrupted information, the on-board computer 15 uses duplicate information generated by the group of fuel level sensors 1 located symmetrically to the rejected group in the first right fuel tank 7. The duplicate information is fed to the corresponding input of the first right module of the fuel meter 11 and, further, to the main input 16 of the right control module 14 and the redundant input 17 of the left control module 13. In the left control module 13 of the on-board computer 15 is calculated in accordance with the algorithmic dependence By (2), the current value of the fuel mass m (τ) ₅ in the first left fuel tank 5 is based on the duplicate information received at the duplicate input 17 of the mentioned module.

Obviously, the replacement of basic information about the amount of fuel in the fuel tank 5 with duplicate information about the amount of fuel in a symmetrically located fuel tank 7 is accompanied by a methodological error δm ₅ (met.) Of measuring the mass of fuel in the fuel tank 5, caused by the inevitable difference in the current values of the mass of fuel in the fuel tanks 5 and 7.

However, the value of the methodical error δm ₅ (met.) Is significantly less than the value of the instrumental error δm ₅ (inst.) Of measuring the mass of fuel in the fuel tank 5 using a rejected group of fuel level sensors 1 installed in this tank:

$$\delta m_5\left(met.\right)<<\delta m_5\left(\mathrm{and}n\mathrm{from}tR.\right).\left(\mathrm{four}\right)$$

The inequality (4) obtained for the fuel tank 5 is valid for any n-th fuel tank 5, 6, 7, 8:

$$\delta m_n\left(met.\right)<<\delta m_n\left(\mathrm{and}n\mathrm{from}tR.\right),\left(5\right)$$

where δm _n (met.) and δm _n (instr.) are the methodological and instrumental errors of measuring the mass of fuel in the nth fuel tank, respectively.

Inequality (5) determines the appropriateness and effectiveness of the metrological parry of the catastrophic failure of the fuel level sensor 1 in any of the fuel tanks 5, 6, 7, 8 by replacing the basic information about the fuel level with duplicate information.

- In addition to measuring the mass fuel supply in the fuel tanks 5, 6, 7, 8 and on the aircraft as a whole, the proposed system controls the symmetry of fuel production from the fuel tanks 5, 6, 7, 8 by aircraft engines on the left and right sides in flight. The purpose of control is to prevent violation of the transverse alignment of the aircraft due to a significant difference in the amount of fuel in the symmetrically located fuel tanks 5 and 7, 6 and 8.

The balance of the aircraft’s fuel balance by the proposed system is carried out by periodically comparing in the comparison device 27 current values of the fuel mass m (τ) ₅ with mass m (τ) ₇ and fuel mass m (τ) ₆ with mass m (τ) ₈ in each pair located fuel tanks 5, 7 and 6, 8.

The current value of the fuel mass m (τ) _n in the nth fuel tank 5, 6, 7, 8 is calculated in accordance with the algorithmic function given in the right part of expression (2) in one of the control modules 13, 14 corresponding to the board of the aforementioned tank, and is transmitted from the output of this module through the corresponding information lines of communication to the input of the comparison device 26.

In the comparison device 26, the current value of the fuel unbalance in the symmetrically located fuel tanks 5 and 7, 6 and 8 of the opposite sides of the aircraft is calculated in accordance with the equalities:

$$\begin{array}{c}\Delta m{\left(\tau \right)}_{\mathrm{one}}=m{\left(\tau \right)}_5-m{\left(\tau \right)}_7,\\ \Delta m{\left(\tau \right)}_2=m{\left(\tau \right)}_6-m{\left(\tau \right)}_8,\end{array}\left(6\right)$$

where Δm (τ) ₁ and Δm (τ) ₂ , are the current values of the fuel imbalance between the first fuel tanks 5 and 7, respectively, and the second fuel tanks 6 and 8, respectively;

m (τ) ₅ , m (τ) ₆ , m (τ) ₇ and m (τ) ₈ , are the current values of the fuel mass in each of the fuel tanks 6, 7, 8, and 9, respectively.

To ensure nominal lateral alignment of the aircraft, each of the absolute values of the fuel unbalance | Δm (τ) ₁ | and | Δm (τ) ₂ | obtained in accordance with expressions (6), must not exceed the maximum permissible value of the fuel unbalance Δm (τ) _max established for each pair of fuel tanks 5, 7 and 6, 8:

$$\begin{array}{c}|\; |\; |\Delta m{\left(\tau \right)}_{\mathrm{one}}|\; |\; |\le \Delta m{\left(\tau \right)}_{\mathrm{one}\max },\\ |\; |\; |\Delta m{\left(\tau \right)}_2|\; |\; |\le \Delta m{\left(\tau \right)}_{2\max },\end{array}\left(7\right)$$

where | Δm (τ) ₁ and | Δm (τ) ₂ | - absolute values of the fuel imbalance between the first fuel tanks 5 and 7 and the second fuel tanks 6 and 8, respectively;

Δm (τ) _1max and Δm (τ) _2max are the maximum permissible values of the fuel unbalance between the mentioned fuel tanks.

The maximum allowable values of the fuel unbalance are entered into the memory of the balancing device 27 when loading the working program. The current algebraic values of the fuel unbalance calculated in the comparison device 26 in accordance with expressions (6) are received via the information line from the output of the latter to the input of the balancing device 27, in which the absolute values of the received values of the fuel unbalance are compared with the maximum allowable values in accordance with the inequalities ( 7). With a significant imbalance of symmetrically located fuel tanks 5, 7 and 6, 8, one or both of the inequalities (7) are not satisfied. In this case, in the balancing device 26, the sign of the current value of the unacceptable imbalance is taken into account: “plus” or “minus” obtained in the comparison device 26 in accordance with expressions (6).

In the case of the minus sign in the balancing device 27, a signal is generated for pumping fuel from the right fuel tank 7 or 8 to the symmetrically located left fuel tank 5 or 6, respectively, and in the case of the plus sign, on the contrary, from the left fuel tank 5 or 6 into a symmetrically located right fuel tank 7 or 8, respectively.

The generated fuel transfer control signal is transmitted from one of the outputs of the balancing device 27 to the corresponding input of external systems of the aircraft 34 to control the directed pumping of fuel from the fuel tank 5, 6, 7, 8 with a larger mass of fuel compared to the nominal fuel tank 5, 6, 7, 8 with a lower mass of fuel compared to the nominal.

Directional fuel transfer continues until inequalities (7) are satisfied in balancing device 27, after which this device removes the fuel transfer signal from the corresponding input of external systems of the aircraft 34.

.When calculating the current values of the fuel unbalance in the comparison device 26 in accordance with equalities (6), a significant part of the calculation error arises due to the difference between the transfer functions of the left and right control modules 13, 14. If the mentioned differences are significant, a reliable determination of the amount of fuel unbalance by the proposed system turns out to be embarrassing. Therefore, in the case when a difference between the transfer functions of the left and right control modules 13, 14 is detected, which causes a significant instrumental error in determining the fuel imbalance, the proposed system can be transferred to the normalization (averaging) mode of the transfer functions of the mentioned modules. The transition to normalization mode is necessary if during operation of the proposed system one of the failed control modules 13, 14 is replaced by a working module if significant differences in the transfer functions of the said modules are detected during the control tests of the proposed system, etc. When the operator enters normalization mode, the operator generates a “normalization” command on the control panel 28 and transmits a normalization command 15 to the on-board computer 15, according to which the current value of the fuel mass m (τ) _n in the nth fuel tank is calculated, with the aim of averaging the transfer functions, not in one but in each of the control modules 13, 14 and is transmitted from the output of each of them via the corresponding information lines to the input of the comparison device 26, in which the arithmetic average of two current mass values: $$\overline{\text{m (}{\tau }_{\text{n}}\text{)}}$$

.

.Similarly, the current value of the fuel mass m (τ) _{n + 2} in the (n + 2) -m fuel tank of the opposite side, located symmetrically to the n-th fuel tank, is calculated in each of the control modules 13, 14 and transmitted from the output of each of them on the corresponding information communication lines to the input of the comparison device 26, in which the arithmetic average of two calculated current mass values is determined: $$\overline{m{\left(\tau \right)}_{n+2}}$$

.

In normalization mode, the comparison device 26 calculates the current value of the fuel imbalance Δm (τ) between the nth and symmetrically located (n + 2) -m fuel tanks in accordance with the expression:

$$\Delta m\left(\tau \right)=\overline{m{\left(\tau \right)}_n}-\overline{m{\left(\tau \right)}_{n+2}},\left(8\right)$$

и $$\overline{m{\left(\tau \right)}_{n+2}}$$

- средние арифметические текущих значений массы топлива в n-м и (n+2)-м топливных баках соответственно.Where $$\overline{m{\left(\tau \right)}_n}$$

and $$\overline{m{\left(\tau \right)}_{n+2}}$$

- arithmetic average of the current values of the mass of fuel in the nth and (n + 2) -m fuel tanks, respectively.

The value of the fuel imbalance calculated by formulas (8), in contrast to the value calculated by formulas (6), is practically independent of the instrumental error caused by differences in the transfer functions of the left and right control modules 13 and 14.

Let us illustrate, by way of example, the process of calculating the current value of the mass of fuel in one of the fuel tanks 5, 6, 7, 8 in normalization mode. For example, when calculating the current value of the fuel mass m (τ) ₅ in the first left fuel tank 5, analog information about the values of the fuel parameters is received from the output of each of the fuel parameter sensors 1 and 2 installed in this tank, to the corresponding inputs of the first left fuel gauge module 9 and then from the output of this module, already in digital form, it enters the main input 16 of the left control module 13 and to the redundant input 17 of the right control module 14 through the corresponding communication lines. In the left control module 13 it calculates This is the main current value of the fuel mass m (τ) ₅ in the fuel tank 5, and in the right control module 14, the duplicate value of the fuel mass m '(τ) ₅ in the mentioned tank. The calculated values of the masses of fuel are transmitted from the output of each of the control modules 13, 14 through the corresponding information lines to the input of the comparison device 26, in which the arithmetic average of the current value of the mass of fuel in the first left fuel tank 5 is calculated:

$$\overline{m{\left(\tau \right)}_5}=0.5\left[m{\left(\tau \right)}_5+m\text{'}\text{'}{\left(\tau \right)}_5\right],\left(9\right)$$

where m (τ) ₅ and m '(τ) _5, respectively, are the main and duplicate current values of the fuel mass in the first left fuel tank 5.

Similarly, the arithmetic average of the current value of the mass of fuel in the first right fuel tank 7 is calculated:

$$\overline{m{\left(\tau \right)}_7}=0.5\left[m{\left(\tau \right)}_7+m\text{'}\text{'}{\left(\tau \right)}_7\right].\left(10\right)$$

The arithmetic mean values of the current fuel mass in the fuel tanks 5 and 7 obtained in the comparison device 26 are used to determine the updated value of the fuel unbalance between the fuel tanks 5 and 7 in the normalization mode:

$$\Delta m{\left(\tau \right)}_{\mathrm{one}}=\overline{m{\left(\tau \right)}_5}-\overline{m{\left(\tau \right)}_7},\left(\mathrm{eleven}\right)$$

и $$\overline{m{\left(\tau \right)}_7}$$

- средние арифметические текущих значений массы топлива в первом левом и в первом правом топливных баках 5 и 7 соответственно, вычисленные в режиме нормализации.Where $$\overline{m{\left(\tau \right)}_5}$$

and $$\overline{m{\left(\tau \right)}_7}$$

- arithmetic average of the current values of the fuel mass in the first left and first right fuel tanks 5 and 7, respectively, calculated in the normalization mode.

In the same way, in the comparison device 26, an updated value of the fuel unbalance between the fuel tanks 6 and 8 is determined in the normalization mode:

$$\Delta m{\left(\tau \right)}_2=\overline{m{\left(\tau \right)}_6}-\overline{m{\left(\tau \right)}_8}.\left(12\right)$$

The values of the fuel unbalance obtained by formulas (11) and (12) are transferred from the comparison device 26 via the information communication line to the balancing device 27, in which, in accordance with inequalities (7), the magnitude and sign of the unbalance are analyzed.

The application in the proposed system of the principle of normalizing the instrumental error of measuring instruments arising due to the difference in their transfer functions allows you to control the balance of the aircraft with respect to fuel even when the transfer functions of the said measuring means - control modules 13 and 14 - differ significantly from each other.

- As the supply of fuel filled on the ground by aircraft engines of a flying airplane is depleted, the current values of the fuel level h (τ) _n in each of the fuel tanks 5, 6, 7, 8 continuously decrease down to the levels at which the low fuel level warning devices 3 are installed.

When the fuel level in any of the fuel tanks 5, 6, 7, 8 reaches a value equal to the installation height of the low fuel level switch 3, the latter generates a signal that the reserve fuel balance has been reached. This signal from the output of the triggered low fuel level warning device 3 is fed to the corresponding input of the on-board computer 15, in which a signal is generated and transmitted via the corresponding communication lines to the aircraft's external systems 34 and to the indicator 30 of the control panel 28 about the reserve fuel remaining in one of the fuel tanks 5, 6, 7, 8 for the crew to decide on the continuation of the flight. In this case, the indicator "reserve balance" and the number of the corresponding fuel tank may be displayed on the indicator 30.

In view of the importance of the signal about the reserve fuel remaining directly affecting flight safety, in the proposed system, the main signal generated by the low fuel level switch 3 can be supplemented by duplicate signals about the reserve fuel remaining, which are generated by the on-board computer 15 based on the measurement information generated by independent sources information using physical measurement principles that differ significantly from the measurement principle of the low fuel level switch 3.

Duplicate signals about the reserve fuel balance can be formed by the flow meter and fuel meter parts of the proposed system. The fuel gauge part of the proposed system, which is responsible for generating one of the duplicate signals about the reserve fuel balance, includes fuel temperature sensors 2, fuel gauge modules 9, 10, 11, 12 and control modules 13, 14 and during the flight, in addition to information on temperature values fuel, can also generate information about the reserve fuel remaining, in the case when the fuel temperature sensors 2 are installed in the fuel tanks 5, 6, 7, 8 at the height of the low fuel level warning devices 3. When the fuel level is lowered in one of fuel tanks 5, 6, 7, 8 below the installation height of said sensor 2, the output signal of the latter changes abruptly due to the abrupt change in ambient temperature when replacing liquid fuel with gas. The output signal jump is transmitted through the corresponding fuel gauge module 9, 10, 11, 12 to the on-board calculator 15. In this case, the on-board calculator 15 generates and from its output enters the aircraft’s external systems input 34 the first duplicate signal on reaching the reserve fuel balance .

The flow meter part of the proposed system includes an on-board computer 15, containing inputs for communication with each of the fuel consumption sensors 33, interacting with the proposed system. The value of the total fuel remaining m (τ) by the flow meter is determined in the on-board calculator 15 in two stages: first, the current value of the fuel consumption from the nth fuel tank 5, 6, 7, 8 is integrated over the flight time, and then the value of the calculated definite integral equal to the mass of fuel consumed from the nth fuel tank is subtracted from the mass of fuel charged into this tank.

The resulting difference is the fuel supply m (τ) _n in the nth fuel tank 5, 6, 7, 8 in the flow meter. The values of the fuel reserves calculated in the on-board calculator 15 by the flow meter m (τ) _n in each of the fuel tanks 5, 6, 7, 8 are transmitted from the outputs of each of the control modules 13, 14 through the corresponding communication lines to the input of the comparison device 26 in which the value of the total fuel reserve m (τ) for the flow meter:

$$m\left(\tau \right)={\Sigma }_{n}m{\left(\tau \right)}_n,\left(13\right)$$

where ∑ _n is the summation symbol n of the current values of the fuel mass m (τ) _n in each of the fuel tanks 5, 6, 7, 9.

Obtained in accordance with equality (13), the value of the total fuel supply for the flow meter is compared with the minimum allowable fuel supply on the plane:

$$m\left(\tau \right)\ge m{\left(\tau \right)}_{\min };\left(\mathrm{fourteen}\right)$$

the value of m (τ) _min is entered into the memory of the comparison device 26 when loading the working program.

If inequality (14) is not satisfied, a second duplicate signal is generated in the comparison device 26 and, from its output, is transmitted to the corresponding input of the external systems of the aircraft 34 to achieve the reserve fuel balance.

Since all three of the mentioned signals about the reserve fuel remainder are generated by the proposed system using three different sources of information using substantially different and independent physical principles of measuring fuel parameters, the probability of simultaneous significant distortion of two of the three signals about the reserve fuel remainder is unlikely.

This provides the crew with the opportunity to reliably evaluate the reliability of the fuel reserve remaining teams based on the simplest majority logic for three independent random events according to the “two out of three” principle.

Therefore, the information on the reserve fuel balance generated by the proposed system is highly reliable and reliable not only in the regular, but also in the emergency mode of operation of the system: in case of failure of one of the sensors forming this information, or in case of significant distortion of one of the signals about the achievement of the reserve fuel balance .

Thus, in the proposed on-board fuel control system with compensation for fuel temperature, the problem was solved by metrological aggregation of fuel information generated by several independent sources, by parrying the information of failed sensors with information from serviceable sensors located symmetrically by the failed ones, and by majority signal generation of the reserve fuel remaining in two of three different independent signals.

Claims (1)

Fuel temperature-compensated on-board fuel control system comprising an on-board computer, a comparison device, a fueling device, an indicator, a balancing device equipped with outputs for transmitting fuel transfer control signals to external aircraft systems, low fuel level warning devices installed in the fuel tanks, as well as installed in fuel tanks sensors of fuel parameters: level and temperature, connected to an on-board computer equipped with inputs for connecting to flow sensors yes fuel, an output for connecting using an information line to external systems of the aircraft and an output connected using an information line to the input of the comparison device, characterized in that it additionally introduces right and left control modules, each of which is equipped with a main and backup inputs, right and left fuel gauge modules, control panel, fuel density adjuster, fuel level indicators installed in the fuel tanks, as well as left and right control channels and right and left memory cells, the number of control channels and the number of memory cells, each equal to the number of fuel tanks, while the on-board computer is supplemented with an input for connecting using the communication line to the roll angle and pitch sensor of the aircraft, the comparison device is supplemented with an output for connecting to external systems aircraft, fuel temperature sensors are installed at the height of the lower fuel level warning devices, the right and left memory cells are part of the right and left control modules, respectively, control modules and control channels are part of the on-board computer, and the fuel density adjuster, indicator and refueling device are part of the control panel, in addition, each of the right fuel gauge modules is connected via the corresponding data lines to the main input of the right control module and to the redundant input of the left control module, and each of the left fuel gauge modules is connected using the corresponding information lines to the main input of the left control module and to the redundant input of the right module communications, control modules are interconnected by a two-way communication line, and each of the right and each of the left control channels is connected by a corresponding two-way communication line to one of the inputs of the corresponding control module, in addition, the control panel is connected to the on-board computer by a two-way communication line, output the fuel density setpoint and the output of the fueling device are connected, each, with one of the indicator inputs, the outputs of each of the fuel level sensors, installed in the same fuel tank, are interconnected and connected to one of the inputs of the fuel meter module corresponding to this tank, and the output of the fuel temperature sensor installed in the same fuel tank is connected to the other input of the mentioned module, in addition, the output of each of the lower level indicators fuel is connected to one of the inputs of the on-board computer, the output of each of the control modules is connected using the corresponding information line to the output of the on-board computer connected to the comparison device, sub connected using the information line to the balancing device.