JPH0426694B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Application> The present invention relates to a fuel weight remaining amount measuring device for an aircraft. More specifically, this invention measures the liquid level and density in a fuel tank installed on an aircraft by converting it into pressure using a pressure transducer, and also uses a pressure transducer to measure the absolute pressure inside the fuel tank. The present invention relates to an improvement in an apparatus for measuring the remaining fuel weight of an aircraft having a structure in which the remaining fuel weight is measured by a user and the measured values are guided to a processor unit to calculate the remaining fuel weight.

<Conventional technology> Conventional fuel weight remaining amount measuring devices use a capacitance type liquid level meter, and the capacitance, which is the output of this liquid level meter, is proportional to the fuel level and fuel electrostatic coefficient. This is used to measure the weight of fuel remaining in the fuel tank installed on the aircraft.

The conventional technology will be explained below with reference to the drawings.

FIG. 3 is a block diagram of a conventional fuel weight remaining amount measuring device for an aircraft.

In FIG. 3, reference numeral 1 designates a fuel tank provided in, for example, the main wing of an aircraft, and stores fuel 2, and 3 designates a capacitance type liquid level gauge. This liquid level meter 3 measures the fuel 2 over the entire range inside the fuel tank 1.
Because it is necessary to measure the liquid level δ of 4 is a compensator unit provided for correcting the fuel dielectric coefficient K of the fuel 2; 5 is a density meter for measuring the density ρ of the fuel 2; and 6 is a processor unit. This processor unit 6 processes information such as "liquid level (δ) - volume (V) characteristics" and measured values as shown in the liquid level/volume characteristic diagram in FIG. 4, an example of which matches the shape of the fuel tank 1. A capacitance input interface (hereinafter referred to as "I/
8 and the frequency input I/F 9 to which the density meter 5 is connected, input values such as the total weight of the aircraft and the required amount of refueling, and output the calculation results of the calculation function described later. an input/output I/F 10 that performs calculations, and a calculation function 1 that inputs information stored in the memory 7 and input values via a data bus 11 and performs calculations.
It is composed of 2.

The calculation operation of this fuel weight remaining amount measuring device is as follows.

The capacitance input I/F 8 is connected to the output of the liquid level meter 3 (capacitance Q ₁ , Q ₂ , ~Q _o ) which is proportional to the liquid level δ ₁ , δ ₂ , ~δ _o of the fuel 2 at each position. ) and a correction value for correcting the fuel dielectric coefficient K of the fuel 2 is input from the compensator unit 4. The calculation function 12 corrects the influence of the fuel electrostatic coefficient K included in the capacitances Q ₁ , Q ₂ , ~Q _o , obtains correction liquid levels δ ₁₁ , δ 21 , ~ δ _o1 , and calculates the correction liquid levels δ 11 , δ ₂₁ , ~δ o1. Regarding the positions δ ₁₁ , δ ₂₁ , .about.δ _o1 , the respective volumes V are further converted using the δ-V characteristic adapted to the shape of the fuel tank 1 stored in the memory 7 .

When the aircraft tilts (for example, when it rolls)
For example, the immersion height δ and the liquid level inclination angle φ are calculated from the detected values of the two liquid level meters 3, and the δ, φ-V characteristics (fuel tank The curve varies depending on the shape, and the characteristic curve of the immersion height (δ) from the bottom of the specific fuel tank, the inclination angle (φ), and the fuel volume (V) is obtained to determine the predetermined fuel volume V. This is multiplied by the density ρ measured by the density meter 5 to obtain the remaining fuel weight W.

However, such a fuel weight remaining amount measuring device has the following problems.

A large number of capacitive level gauges are required. For this reason, the wiring requires the use of a large number of coaxial cables or shielded wires that are routed independently, and the weight of the wiring cannot be ignored. Particularly if the fuel tank is located far from the processor unit, weight increase due to distance must also be taken into consideration.

It is necessary to appropriately characterize the shape of the fuel tank by changing the shape of the inner electrode of the liquid level meter. Since the outputs of the liquid level gauges, which are proportional to the fuel volume, are connected in parallel with each other, if one of them is disconnected, failure cannot be detected immediately, resulting in an error.

Capacitive liquid level gauges are susceptible to vibration and have poor maintainability.

Therefore, the applicant of the present application first filed Japanese Patent Application No. 194248 (hereinafter referred to as "Prior Art 1") in order to solve the problems of this conventional technology. This prior art 1 will be explained below with reference to a block diagram of a fuel weight remaining amount measuring device for an aircraft shown in FIG.

In FIG. 5, reference numeral 13 is a pressure transducer, which is installed at the bottom of the fuel tank and measures the immersion height H of the fuel 2 as pressure, in place of the capacitive liquid level meter 3 and the compensator unit 4. There are multiple liquid level detectors (here, a case of three is shown, but three or more may be provided to improve safety). These plurality of liquid level detectors 13 are constituted by absolute pressure measurement sensors of a type in which pressure is output as a frequency signal. Here, the reason why the three liquid level detectors 13a to 13c were installed at predetermined intervals l and k is because the flying object tilts not only left and right but also forward and backward (so-called tilting when rolling or pitching). This is to obtain the liquid level inclination angle (θ, φ) at this time. Reference numeral 15 denotes an internal pressure detector configured with a pressure transducer that is set at a position not in contact with the fuel 2 in the fuel tank 1 and measures the absolute pressure P ₀ in the fuel tank 1. Normally, the inside of the fuel tank 1 is overpressured by about 3 psi (approximately 0.2 kg/cm ² ) in a flying vehicle. Reference numeral 16 denotes an accelerometer for measuring acceleration g, which is provided to correct the acceleration of the flying object.
17 is a processor unit to which a liquid level detector 13, a density meter 5, an internal pressure detector 15, and an accelerometer 16 are connected, and calculates the remaining amount of fuel weight in the fuel tank 1 from the respective detected values and measured values. be. This processor unit 17 includes a memory 18 that stores information such as an immersion height that matches the shape of the fuel tank 1, an inclination angle-volume characteristic, measured values, etc., a liquid level detector 13, a density meter 5, and an internal pressure sensor. Frequency input I/F 19 to which the detector 15 is connected and the accelerometer 16
an acceleration signal I/F 20 to which is connected, and an input/output I/F 2 to input this information and, for example, information on the required amount of fuel refueling and output calculation results.
3 and an arithmetic function 22 which inputs information from 3 via a data bus 21 and performs arithmetic operations.

The measured pressure P obtained from each of the liquid level detectors 13a to 13c is as follows: P=ρ·g·H+P ₀ (1). Therefore, the liquid level H is as follows: H=(P−P ₀ )/ρ·g (2). On the other hand, the volume V is expressed as a function of the immersion height H: V=f(H) (3).

Now, if the liquid level is inclined as shown by π (inclination angle φ), the liquid level detectors 13a, 13
A liquid level detector 13 is located at a distance k from b.
c is installed, the liquid level detector 13
Immersion height (liquid level) from a or 13b and 13c
H and the liquid level inclination angle φ are calculated, and the fuel volume V is obtained from the H, φ-V characteristics in the memory 18, and W=ρ・
The fuel weight remaining amount W can be determined from V.

Further, when the liquid level is inclined as shown by ω (inclination angle θ), the liquid level detectors 13a, 13
A liquid level detector 13 is located at a distance l from c.
b is installed, so the liquid level detector 13
The immersion height H and the liquid level inclination angle θ are calculated from a or 13c and 13b, the fuel volume V is obtained from the H, θ-V characteristics in the memory 18, and the remaining fuel weight W is obtained from W=ρ・V. be able to.

By the way, according to Prior Art 1, by configuring the liquid level detector 13 and the internal pressure detector 15 with pressure transducers, it is possible to suppress the weight increase compared to the conventional technology, but it is possible to suppress the weight increase compared to the conventional technology. This makes it an expensive product. In addition, while it is common to measure the remaining fuel weight of an aircraft based on changes in fuel density, this prior art 1
The density is obtained by a point measurement method that is set at one point, so if there is a change in density, it is not possible to accurately calculate the average fuel density (volume x density), resulting in poor absolute accuracy. Furthermore, an error in the accelerometer directly becomes an error in the remaining fuel amount, and at the same time, a mismatch in sampling time for signal processing also becomes an error when the acceleration changes. In other words, when correcting acceleration using an accelerometer, if there is a 1% error in the acceleration sensor, it will directly appear as a remaining fuel error, which is a big problem, especially in an environment where acceleration is applied, such as in an aircraft. .

Therefore, the applicant of the present application further filed Japanese Patent Application No. 1983-22366 (hereinafter referred to as "Prior Art 2") as a technique for solving such problems. Hereinafter, this prior art 2 will be measured using the block diagram of the apparatus for measuring the remaining fuel weight of an aircraft shown in FIG.

The characteristics of Prior Art 2 are that a density sensor and an acceleration sensor are not used, and only a plurality of pressure transducers are used to avoid the influence of acceleration during signal processing, and the liquid level is determined without making any correction based on the acceleration signal. It is configured to measure the remaining fuel weight by measuring the level and the angle of inclination of the liquid surface.

In FIG. 6, 24 is an auxiliary liquid level detector composed of a pressure transducer. This auxiliary liquid level detector 24 is located approximately directly above at least one of the plurality of liquid level detectors 13a to 13c, which are also constituted by pressure transducers, and in this example, the liquid level detector 13b. They are installed in the fuel 2 (liquid level 2a) at constant intervals μ. 25 is a processor unit to which the liquid level detectors 13a to 13c, the auxiliary liquid level detector 24, and the internal pressure detector 15 are connected, and calculates the remaining fuel weight W from the measured values of each of these detectors. .
This processor unit 25 has a memory 26 that stores information necessary to calculate the immersion height, inclination angle-volume characteristics, various fuel weight remaining amounts, etc. that match the shape of the fuel tank 1, and the liquid level level. Detector 13
and a frequency input I/F 27 to which the auxiliary liquid level detector 24 and the internal pressure detector 15 are connected, and an input/output I/F 30 to which, for example, information on the required amount of fuel refueling is input and calculation results are output. , each of the above I/
It is comprised of an arithmetic function 29 that inputs information from F and information from memory via a bus 28 and performs arithmetic operations.

The aircraft pitches and rolls. Therefore, in order to accurately determine the fuel weight remaining amount W, it is necessary to perform a liquid level inclination angle correction calculation (pitch angle correction calculation or roll angle correction calculation).

Here, fuel tank 1 when the aircraft rolls
In the case of calculating the remaining fuel weight W in the above, that is, the case of performing the roll angle correction calculation using the outputs of the liquid level detectors 13a to 13c, the auxiliary liquid level detector 24, and the internal pressure detector 15, This will be explained using the state diagram of the fuel tank 1 when the aircraft rolls at the roll angle φ shown in FIG.

Now, the liquid level detector used when rolling is 1
3b and 13c, and the measured pressures are P _b1 and P _c .
From equation (1), the following can be obtained: P _b1 = ρ・g・h _b1 +P ₀ (4) P _c =ρ・g・h _c +P ₀ (5). However, h _b1 and h _c are liquid levels in a direction perpendicular to the liquid level 2a of the liquid level detectors 13b and 13c. The mutual relationship between h _b1 and h _c is h _c = h _b1 − ksinφ (6). Similarly, the auxiliary liquid level detector 24
When the measured pressure of is P _b2 , P _b2 = ρ・g・h _b2 + P ₀ (7). However, h _b2 is the auxiliary liquid level detector 24
This is the liquid level in the direction perpendicular to the liquid level 2a. Here, the liquid level inclination angle φ is determined. From equations (4) to (7), we obtain P _b1 −P _c =ρ・g・ksinφ (8) P _b1 −P _b2 =ρ・g・μcosφ (9). From equations (8) and (9), tanφ=(μ/k) {(P _b1 −P _c )/(P _b1 −P _b2 )} (10) is obtained. In general, for commercial aircraft, a pitch angle of ±10° and a roll angle of ±3° are sufficient, and in this case it is sufficient to characterize it by tanφ.

Next, find the liquid level Hb ₁ . Transform equation (4) to obtain ρ・g, and use equations (8) and (10) to determine the liquid level.
When calculating Hb ₁ , H _b1 = μ(P _b1 − P ₀ )/(P _b1 − P _b2 ) …14.

From the liquid level Hb ₁ and the liquid level inclination angle φ obtained above, the fuel volume V is determined using the Hb ₁ and φ-V characteristics in the memory 26.

Next, find the fuel density ρ. By transforming equations (8) and (9), we obtain sinφ=(P _b1 −P _c )/ρgk …12 cosφ=(P _b1 −P _b2 )/ρgμ …13. From both equations, (sinφ) ² + (cosφ) ² = {(P _b1 − P _c ) ² + (P _b1 − P _b2 ) ²・(k/μ) ² }/(ρgk) ² = 1 …14 get. Here, since the rate of change of the density ρ is longer than the rate of change of the acceleration g, for example, if the signal is processed to remove the component of the acceleration g through a low-pass filter, it can be handled as "g=1". Therefore, equation (14) becomes ρ={(P _b1 − P _c ) ² + (P _b1 − P _b2 ) ² (k/μ) ² } ^1/2 /k …15, and the density ρ can be found. I can do it. In addition, if the signal of acceleration g can be easily obtained from another source to find the density ρ, that is, if it is input as an input signal to other instruments, etc., use this signal of acceleration g. Good too. Of course, even if the acceleration signal is input from the outside and corrected, it will not cause a large error because the time constant of change of the density ρ is long (because the noise is longer than the low-pass filter).

The fuel volume V is determined from a pre-stored memory calculated based on V=f(Hb ₁ , φ), f(Hb ₁ , θ), f(Hb ₁ , φ, θ)...16 You can get the value of

Therefore, the remaining fuel weight W is determined by the density ρ and the fuel volume V
From this, it can be determined by the formula W=ρ·V.
FIG. 8 summarizes the above calculation system as a flow sheet.

In addition, in the case where the liquid level detector 13b is shown in FIG. 7, it is treated as being on the same axis as 13a, but 1
If 3a and 13b are on different axes, e.g.
When 3a to 13c are configured in a triangular shape, the combination of liquid level detectors at that time is 13a.
(Pa) and 13b (Pb ₁ ) and auxiliary liquid level detector 2
4 (Pb ₂ ), similar results can be obtained. or,
Although the case of the roll angle φ has been described above, the pitch angle θ can be determined by a similar calculation method, assuming that the distance k between the liquid level detectors is l. At this time, suppose the combination of liquid level detectors is 13a (Pa) and 13b (Pb ₁ ) as shown above.
and auxiliary liquid level detector 24 (Pb ₂ ),
The flow becomes as shown by the broken line in FIG. 8, and tanθ can be obtained. Furthermore, although one auxiliary liquid level detector 24 is disposed approximately directly above the liquid level detector 13b, it may also be disposed approximately directly above the liquid level detectors 13a and 13c, respectively. By doing so, the auxiliary liquid level detector can be made redundant, thereby making it possible to further improve reliability.

<Problems to be Solved by the Invention> By the way, Prior Art 2 has the following problems. For example, as shown by the broken line in FIG. 7, the liquid level Rb 1 of the fuel 2 is below the installation position of the auxiliary liquid level detector 24 (i.e., when the value of μ can no longer be obtained) as shown by _2b. (Rb horizontally), it is no longer possible to obtain a normal remaining fuel weight (that is, the liquid level of fuel 2 is Rb, Rb ₁
(In this case, the expression containing “μ” no longer holds true.)

The present invention has been made in view of the problem of Prior Art 2, and even if the auxiliary liquid level detector becomes unusable, the detected values of multiple liquid level detectors can be used. It is an object of the present invention to provide a fuel weight measuring device that can be used to accurately measure the remaining amount of fuel weight.

<Means for Solving the Problems> To achieve this purpose, the fuel weight remaining amount measuring device of the present invention measures the remaining fuel weight amount in a fuel tank installed on an aircraft. The liquid level of the fuel in the fuel tank is detected by a plurality of liquid level detectors each comprising a pressure transducer. An auxiliary liquid level detector consisting of a pressure transducer is installed to obtain fuel density information, and an internal pressure detector consisting of a pressure transducer is set in a non-contact state to the fuel to detect the temperature inside the fuel tank. The pressure is detected and the detected values of these detectors are input to a processor unit to calculate the remaining fuel weight. At one time, the liquid level, the inclination angle of the fuel tank, the density information of the fuel, etc. are calculated based on the detected values from the plurality of liquid level detectors, the auxiliary liquid level detector, and the internal pressure detector. Then, the fuel weight remaining amount is calculated, and when the fuel is in a non-contact state with the auxiliary liquid level detector, the density information of the fuel immediately before the non-contact state is stored, and the fuel The inclination angle of the fuel tank is calculated based on the detected values from the plurality of liquid level detectors immersed in the liquid level, and the inclination angle of the fuel tank is calculated based on the detected value of at least one of the plurality of liquid level detectors and the internal pressure detection. The liquid level of the fuel is calculated based on the detected value of the device, and the remaining fuel weight of the flying object is calculated based on the stored density information and the calculated liquid level and inclination angle. It is characterized by this.

<Example> The present invention will be described below with reference to the drawings. In the following drawings, parts that overlap with those in FIGS. 3 to 8 will be designated by the same reference numerals and their explanations will be omitted.

FIG. 1 is a block diagram of an apparatus for measuring the remaining fuel weight of an aircraft, which is a specific embodiment of the present invention.

In Fig. 1, 250 indicates when the fuel 2 is out of contact with the auxiliary liquid level detector 24 (therefore, the output of the auxiliary liquid level detector 24 cannot be used, so the wiring is omitted here). This is a processor unit in which the operation flow sheet of FIG. 2 (shown in FIG. 2) is organized into blocks for each calculation function (the hardware configuration is the same as in FIG. For example, now fuel 2
When the liquid level 2b is in the measurement state, the auxiliary liquid level detector 2
If the liquid level Rb is below the installation position of 4,
In other words, if the detection value of the auxiliary liquid level detector 24 can no longer be obtained, the density information ρg obtained based on equation (15) (this g becomes a negligible value when based on equation 15) cannot be detected. It is fixed to the value immediately before the value no longer obtained and is stored in the storage device (memory) 260 (even if this is done, the amount of fuel is relatively small, so the effect of change is small). With ρg stored in the memory 260, the processor unit 2
Detection values Pa, Pb ₁ , and Pc from a plurality of liquid level detectors 13 immersed in the fuel 2 and detection value P ₀ from the internal pressure detector 15 are input to 50 . here,
Detected values Pa from the plurality of liquid level detectors 13,
Pb ₁ and Pc are led to the inclination angle calculating section 31, where the inclination angles θ and φ of the fuel tank 1 are calculated. That is, the values obtained from the liquid level detectors 13b and 13a
From equation (8) based on Pb ₁ and Pa, we obtain Pb ₁ −Pa=ρ・g・l・sinθ …17, and from equations (8) and 17, roll angle φ and pitch angle θ
The value of is obtained as φ=sin ^-1 · {(Pb ₁ -Pc)/ρgk}...18 θ=sin ^-1 · {(Pb ₁ -Pa)/ρgl}...19. At the same time, at least one detected value of the plurality of liquid level detectors 13, for example Pb ₁ (however, depending on design considerations such as calculation method and other installation conditions, other detected values may be detected as shown by the broken line). ) and the detected value P ₀ of the internal pressure detector 15 are guided to the liquid level calculation section 32 . In the liquid level calculation unit 32, the detected values Pb ₁ and P ₀ as well as the inclination angle θ,
The liquid level Rb of the fuel 2 is calculated by inputting φ and the density/acceleration ρ/g (Rb ₁ when the fuel tank 1 is tilted). Now, let us consider a case where the liquid level 2b of the fuel 2 when the aircraft is tilted at a roll angle φ as shown in FIG. 7 reaches a liquid level Rb ₁ as shown by a broken line. The liquid level Rb ₁ is obtained as in 2a when the liquid level of the fuel 2 is μ or more, with Rb ₁ =(Pb ₁ -P ₀ )/ρgcosφ...20. The fuel displacement Rb ₁ when the aircraft is tilted at the pitch angle θ is similarly obtained as Rb ₁ = (Pb ₁ −P ₀ )/ρgcosθ...21. The fuel displacement Rb ₁ when the aircraft is tilted with a roll angle φ and a pitch angle θ is similarly obtained as Rb ₁ =(Pb ₁ −P ₀ )/ρg·cosφ·cosθ …22. The fuel volume calculation unit 33 calculates the volume V of the fuel 2 based on the liquid level Rb, Rb ₁ and the inclination angles θ, φ. That is, from the liquid level Rb ₁ and the roll angle φ and bit angle θ obtained from equations 18 and 19, the fuel volume V is obtained from V=f(Rb ₁ , φ, θ) ...26 based on equation 16. I can do it. The fuel weight calculation unit 34 calculates the remaining fuel weight W of the aircraft from the volume V obtained in this way and the previously fixed ρg.
is calculated as W=V・ρg...27 and output.

In this way, in the present invention, even if the amount of fuel becomes small in the end, at least three liquid level detectors 13a to 13c are immersed in the fuel 2 even when the fuel is at least rolling or pitching. These liquid level detectors 13a to 1
As long as the detected values can be obtained from 3c,
Accurate fuel weight remaining amount W can be calculated.

<Effects of the Invention> As described above in detail along with specific examples, the present invention has been described in detail with reference to an internal pressure detector that measures the absolute pressure inside a fuel tank, which is composed of a pressure transducer, and a plurality of liquid level detectors. The flight of the present invention is configured to calculate the remaining fuel weight based on the detected value of an auxiliary liquid level detector installed at a constant interval substantially directly above at least one of the plurality of liquid level detectors. The body fuel measuring device can easily measure the remaining fuel weight with higher accuracy even when making a balanced turn, skidding due to lateral acceleration, or applying forward acceleration.
:The liquid level and liquid level inclination angle are measured without being affected by acceleration during signal processing, and without correction by acceleration signals, and the fuel in the fuel tank installed on the aircraft is measured with high precision. The remaining weight can be measured. : We provide a highly reliable fuel weight remaining amount measuring device that has a simple configuration, is vibration resistant, and has excellent maintainability such as inspection and maintenance by significantly reducing the total weight of the device while maintaining high accuracy and performance at a low price. can do. : Even when the amount of fuel is low, as long as at least three pressure transducers, which are liquid level detectors, are immersed in the fuel, the remaining fuel weight can be measured very accurately. Obtainable.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the fuel weight measuring device for an aircraft according to the present invention, and FIG. 2 is a flow sheet of the present invention.
Fig. 3 is a block diagram of a conventional fuel weight remaining amount measuring device for an aircraft, Fig. 4 is a liquid level/volume characteristic diagram, and Figs. 5 to 8 are prior art and of the present invention. It is a figure provided for explanation. DESCRIPTION OF SYMBOLS 1... Fuel tank, 2... Fuel, 3... Capacitive liquid level meter, 4... Compensator unit, 5... Density meter, 6, 17, 25, 250...
...Processor unit, 13...Liquid level detector, 15...Internal pressure detector, 24...Auxiliary liquid level detector.

Claims (1)

[Scope of Claims] 1. A plurality of liquid level detectors that detect the liquid level of fuel in a fuel tank installed on an aircraft;
an auxiliary liquid level detector installed at a constant interval substantially directly above at least one of the plurality of liquid level detectors and outputting density information of the fuel;
The system includes an internal pressure detector that is set in a non-contact state with the fuel to detect the pressure inside the fuel tank, and a processor unit that is connected to each of these detectors and calculates the remaining amount of fuel weight. In the apparatus for measuring the remaining fuel weight of an aircraft, the detector is comprised of a pressure transducer, and the processor unit is configured to detect when the fuel is above the installation position of the auxiliary liquid level detector. the plurality of liquid level detectors;
Calculating the remaining fuel weight after calculating the liquid level, the inclination angle of the fuel tank, the density information of the fuel, etc. based on the detected values from the auxiliary liquid level detector and the internal pressure detector, When the fuel is in a non-contact state with the auxiliary liquid level detector, the density information immediately before the non-contact state is stored, and information from the plurality of liquid level detectors immersed in the fuel is stored. The inclination angle of the fuel tank is calculated based on the detected value of the fuel tank, and the liquid level of the fuel is calculated based on the detected value of at least one of the plurality of liquid level detectors and the detected value of the internal pressure detector. An apparatus for measuring remaining fuel weight of an aircraft, characterized in that the remaining fuel weight of the aircraft is subsequently calculated based on the stored density information and the calculated liquid level and inclination angle.