JPH042480B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Field of Application> The present invention provides a method for measuring fuel in a fuel tank attached to a flying vehicle with attitude fluctuations, particularly based on the fuel level and the liquid level slope value. The present invention relates to a method for measuring the remaining fuel weight of an aircraft by calculating the remaining fuel weight and improving the accuracy of the calculation output.

<Prior Art> A conventional technology will be described using as an example a device for measuring the remaining fuel weight attached to an aircraft, which is a representative type of flying vehicle. In addition, when the fuel level sensor for measuring the fuel level is used in an aircraft, a capacitance type tank unit is generally widely used, so it is hereinafter expressed as "T/U" (abbreviation for tank unit). . Note that this system uses a system with linear changes.

FIG. 3 is a diagram for explaining the conventional technology.

In this case, the fuel level in the fuel tank is measured by T/U, and the angle of inclination of the fuel level is measured using an accelerometer, taking advantage of the fact that the fuel level is perpendicular to acceleration. , it is necessary to calculate the remaining fuel weight based on these fuel levels and liquid level inclination angles.

The conventional technique will be explained below with reference to FIG.

In Figure 3, T/U1 ((T/U in the figure)
a,...(T/U)c) measures the fuel level of fuel Q in the fuel tank T (Z ₁ ,...Z ₃ in the figure) and calculates the acceleration of the aircraft in the X, Y, and Z directions. The fuel level is measured by an accelerometer 3, a liquid level inclination angle is calculated based on the acceleration in a fuel calculating section 2, and a fuel weight remaining amount W is calculated and output based on this liquid level inclination angle and the fuel level.

The fuel calculation unit 2 calculates the liquid level inclination angle with the fuel input interface (hereinafter abbreviated as "I/F") 21 to which the T/U 1 is connected, and calculates the liquid level inclination angle and the fuel level. a calculation function 22 that calculates the fuel weight remaining amount W based on the fuel weight, a storage element (ROM) 23 that stores weighting coefficients corresponding to each setting location, and a random access memory (RAM) 24 that accesses necessary information as appropriate; It consists of an output I/F 25 that outputs this fuel calculation result to the outside, and an acceleration input I/F 26 that inputs an acceleration signal.

<Problems to be Solved by the Invention> By the way, such a fuel measurement system does not measure the accelerometer 3 in response to changes in the installation angle of the aircraft wing.
Obtaining the tilt correction value from the signal does not provide sufficient follow-up. In the case of large aircraft, the fuel tanks are located inside the wings, and the dihedral angle (mounting angle relative to the aircraft) changes depending on various conditions on the ground and in the air, and when acceleration is applied, the fuel tank is located within the wing, and the accurate liquid level slope (fuel tank relative to the fuel It is difficult to detect the slope of the liquid level, which results in an error in the remaining fuel output. The accelerometer 3 for measuring the liquid level inclination angle is usually installed in the fuselage of the aircraft. However, since the installation angle of the wing on which the fuel tank T is installed generally fluctuates, taking this into consideration, the accelerometer 3 must be installed inside the wing to measure the accurate inclination angle, resulting in errors. becomes. Possible cases in which the attachment angle of the wing changes include that the dihedral angle changes greatly between on the ground and in the air, and that the deflection of the wing increases as the fuel Q increases during fuel supply on the ground. When liquid level inclination correction is performed using the acceleration signal from the accelerometer 3, it is fine if the whole does not change, but if the blade is in a state where it is deflected as described above, a deflection error will occur. Therefore, it is not possible to accurately determine the value of the fuel weight remaining amount W.

By the way, it is naturally possible to obtain liquid level slope correction along with the fuel level using at least three T/Us,
With three, the dynamic range with respect to the inclination angle is narrow, and in order to widen the dynamic range, a large number of T/Us are inevitably required. This increases the overall weight, which is unfavorable in terms of maintenance, fuel consumption, etc. There is a problem.

The present invention has been made in view of the problems of the conventional technology, and is a method for measuring the remaining amount of fuel weight in a fuel tank installed in an aircraft that has attitude fluctuations. The fuel level is T/U regardless of whether the aircraft is on the ground or in the air.
The fuel level slope calculation is performed using a technology that uses the value measured with an accelerometer, or everything is measured and calculated using T/U, but in the present invention, the fuel level is measured using T/U. The liquid level slope calculation is performed by three T/Us on the ground, and by an accelerometer in the air, improving the overall liquid level slope calculation accuracy and comparing each liquid level slope calculation value with The purpose of the present invention is to provide a method for measuring the remaining fuel weight of an aircraft, which can accurately and highly accurately measure the remaining fuel weight based on the fuel level determined by T/U, without being affected by the deformation of the wings of the aircraft. shall be.

<Means for Solving the Problems> To achieve the above-mentioned object, the present invention measures the liquid level of fuel in a fuel tank provided in a flying object with a fuel level sensor, and calculates the acceleration of the flying object. A device that measures the remaining fuel weight based on each of these measured values using an accelerometer, which is installed on the aircraft and measures the amount of fuel remaining as the aircraft takes off and lands.
Takeoff and landing confirmation switch 4 that turns ON/OFF and at least three fuel level sensors (T/U ₁ )
and a fuel calculation unit 20 to which the fuel level sensor, the takeoff and landing confirmation switch, and the accelerometer 3 are connected to calculate the remaining fuel weight, and the fuel calculation unit uses the signal from the takeoff and landing confirmation switch to calculate the amount of fuel remaining. When it is recognized that the flying object is in the air, a liquid level slope value of the fuel when in the air is calculated from the signal of the accelerometer, and when the flying object is on the ground is recognized based on the signal of the takeoff and landing confirmation switch. In this case, the liquid level slope value of the fuel when on the ground is calculated from the signals of the at least three fuel level sensors, and the liquid level slope value when the fuel is in the air or the liquid level slope value when on the ground and the fuel level sensor are calculated. This is a method for measuring the remaining fuel weight of an aircraft by calculating the remaining fuel weight from the measured liquid level.

<Examples> Examples of the present invention will be described in detail below based on the drawings. It should be noted that overlapping parts in the drawings shown below and FIG.

FIG. 1 is a diagram showing a specific embodiment of the present invention.

In Fig. 1, numeral 4 is provided on, for example, the landing leg of the aircraft and
ON/OFF takeoff and landing confirmation switch (hereinafter referred to as “GAS”)
20 is T/U1 and GAS SW
4 and the accelerometer 3 are connected to a fuel calculation unit (26 is a GAS SW I/F) that calculates the remaining fuel weight W. This fuel calculation unit 20 is a GAS SW
When it is recognized that the aircraft is in the air based on the signal of 4, the liquid level slope value of fuel Q in the air is calculated from the signal of the accelerometer 3, and when it is recognized that the aircraft is on the ground based on the signal of GAS SW4. is T/U1
Calculate the liquid level slope value of the fuel Q when on the ground from the signal of Calculate the fuel weight remaining amount W.

In the following, in particular, the case where the liquid level slope value of the fuel Q when in the air is calculated from the signal of the accelerometer 3, and the case where the liquid level slope value of the fuel Q when on the ground is calculated from the signal of T/U1 will be explained. .

The fuel calculation unit 20 inputs the contact information of the GAS SW 4 and determines whether the aircraft is on the ground or in the air.

<<When the aircraft is on the ground>> At this time, each of (T/U)a, (T/U)b,
Let the liquid level of (T/U)c be Z ₁ , Z ₂ , and Z ₃ .
Also, these x and y coordinates are (x ₁ , y ₁ ), respectively.
If (x ₂ , y ₂ ), (x ₃ , y ₃ ), the fuel calculation unit 20 calculates the liquid level inclination angles θe and e in the pitch direction and roll direction of the aircraft.

Here, a plane passing through the x-coordinate and y-coordinate point (O, O, Z ₀ ) and having a pitch angle θe and a roll angle e is expressed as Z=x・tan θe+y・tane+Z ₀ (3). On this plane, there are points (x ₁ , y ₁ , Z ₁ ),
(x ₂ , y ₂ , Z ₂ ) and (x ₃ , y ₃ , Z ₃ ), respectively, Z ₁ = x ₁・tanθe+y ₁・tane+Z ₀ ...(4) Z ₂ =x ₂・tanθe+y ₂・tane＋Z ₀ ……(5) Z ₃ =x ₃・tanθe＋y ₃・tane＋Z ₀ ……(6) is satisfied. Therefore, if these equations are solved for θ as simultaneous equations, θe＝tan ^-1・{(Z ₃ −Z ₁ )(y ₃ −y ₂ ) −(Z ₃ −Z ₂ )(y ₃ −y ₁ )} /{(x ₃ −x ₁ )(y ₃ −y ₂ ) −(x ₃ −x ₂ )(y ₃ −y ₁ )} ……(1) e＝tan ⁻¹・{(Z ₃ −Z ₂ )(x ₃ −x ₁ ) −(Z ₃ −Z ₁ )(x ₃ −x ₂ )} / {(x ₃ −x ₁ )(y ₃ −y ₂ ) −(x ₃ −x ₂ )(y ₃ −y ₁ )} ...(2) is obtained. That is, the liquid level slope value of the fuel Q on the ground can be obtained using T/U1.

≪When the aircraft is in the air≫ FIG. 2 is a diagram showing the relationship between acceleration and liquid level.

The liquid level of an aircraft tilts even when subjected to acceleration. Such a change in the liquid level can be treated as a change in pitch angle and roll angle with respect to the tank with respect to the tank. Therefore, when it is recognized that the aircraft is in the air based on the signal from GAS SW4, input the accelerations Ax, Ay, and Az in the x, y, and z directions from the accelerometer 3, and calculate the liquid level slope value of the fuel when it is in the air. can be calculated. When the fuel is in equilibrium with the acceleration,
The liquid level inclination angles θs and s in the pitch and roll directions of the aircraft are calculated by the fuel calculation unit 20 based on the following equations.

The liquid level Q ₁ is in equilibrium on a plane perpendicular to the direction of acceleration α. At this time, the liquid level inclination angle in the pitch direction is θs=tan ^-1 (Ax/Az)...(7) from Figure 2. Similarly, for the liquid level inclination angle in the roll direction, s=tan ^-1 (Ay/Az)...(8). That is, the fuel calculation unit 20 calculates each acceleration Ax,
By inputting Ay and Az, the liquid level slope value of the fuel in the air can be calculated from equations (7) and (8).

From the above, the current remaining fuel weight W of the aircraft can be calculated using the liquid level slope value when in the air or the liquid level slope value when on the ground, and the value of the fuel level measured at T/U1. It is calculated by the fuel calculation section 20. The approximate calculation formula, which is an example of the calculation formula, is as follows: W=Zi+K ₁ θ+K ₂ +K ₃ θ (9). However, K ₁ , K ₂ , and K ₃ are constants that are determined corresponding to the intervals of the fuel level Zi and the liquid level inclination angle calculation value θ, and are obtained using a polygonal line approximation formula.

Although the above explanation has been given for the case where three T/Us are installed, the present invention is not necessarily limited to this, and the present invention can be realized even if four or more T/Us are installed, for example. It is possible.

Further, it goes without saying that the fuel measuring system for an aircraft according to the present invention is not limited to being used in the above-mentioned aircraft, but can be widely used as long as it has similar functions and configurations.

<Effects of the Invention> As described above in detail with the embodiments, according to the present invention: By changing the inclination detection method on the ground and in the air, the advantages of each method can be utilized. Below, we look at the case of a commercial aircraft whose fuel tank is inside the wing: a: On the ground, the aircraft body does not take a tilted attitude, but rather the problem is that the wing bends downward. Therefore, the liquid level slope detection method using T/U can detect the slope including the deflection of the blade, so the deflection of the blade does not cause an error.
As the wing flexes, the number of T/Us immersed in fuel increases, so the disadvantage of this method is that ``At least three T/Us need to be immersed in fuel.
There is no need to worry about the need to increase the number of T/Us.

b: In the air, an aircraft tilts significantly as it ascends, descends, turns, etc., so a liquid level detection method that uses a dynamic range of tilt angle and wide acceleration is advantageous.

c: In this way, by accurately obtaining the liquid level slope value using an appropriate sensor according to the aircraft's current state, the fuel level can be calculated based on this liquid level slope value and the fuel level obtained at T/U. The remaining fuel amount W can be obtained with high accuracy.

:With this configuration (at least 3 T/Us, accelerometers, and GAS SW), it can be installed in any shape of fuel tank.

:The measurement accuracy has been improved by making it possible to calculate the liquid level slope value when the fuel is in the air.

:Since the structure consists of at least three T/Us, it is more resistant to failures than conventional technology, achieving high reliability, and the total number of T/Us can be reduced. , if compared to the accuracy obtained with the prior art.

There are other effects.

[Brief explanation of drawings]

Figure 1 is a diagram showing a specific embodiment of the present invention, Figure 2 is a diagram showing a specific embodiment of the present invention.
The figure is a diagram showing the relationship between acceleration and liquid level, and FIG. 3 is a diagram for explaining the conventional technology. 1...Fuel level sensor (T/U), 2,20
...Fuel calculation unit, 3...Accelerometer, 4...GAS
SW.

Claims (1)

[Claims] 1. Measuring the liquid level of fuel in a fuel tank provided on a flying object with a fuel level sensor, measuring the acceleration of the flying object with an accelerometer, and measuring the remaining fuel weight based on each of these measured values. In the method, a takeoff and landing confirmation switch 4 provided on the aircraft and turned ON/OFF when the aircraft takes off and lands;
, at least three fuel level sensors (T/U ₁ ), and a fuel calculating section 20 to which the fuel level sensors, the takeoff and landing confirmation switch, and the accelerometer 3 are connected to calculate the remaining fuel weight. When the fuel calculation unit recognizes that the flying object is in the air based on the signal of the takeoff and landing confirmation switch, calculates the liquid level slope value of the fuel when it is in the air from the signal of the accelerometer; When it is recognized that the aircraft is on the ground based on the signal from the takeoff and landing confirmation switch, the slope value of the fuel level when on the ground is calculated from the signals from the at least three fuel level sensors, and the liquid level when in the air is calculated. A method for measuring a remaining fuel weight of an aircraft, wherein the remaining fuel weight is calculated from an inclination value or the liquid level inclination value on the ground and the liquid level measured by the fuel level sensor.