CN109406044B - Undercarriage buffer air pressure detection method - Google Patents
Undercarriage buffer air pressure detection method Download PDFInfo
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- CN109406044B CN109406044B CN201811346544.8A CN201811346544A CN109406044B CN 109406044 B CN109406044 B CN 109406044B CN 201811346544 A CN201811346544 A CN 201811346544A CN 109406044 B CN109406044 B CN 109406044B
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- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L17/00—Devices or apparatus for measuring tyre pressure or the pressure in other inflated bodies
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Abstract
The application belongs to the technical field of airplane detection, and particularly relates to an undercarriage air pressure detection method, which comprises the following steps: obtaining P, wherein P is the pressure of a buffer air cavity; obtaining T, wherein T is the internal King temperature of the air cavity of the buffer; obtaining X0 according to P and T, wherein X0 is the theoretical length of the piston rod extending out of the outer cylinder when the buffer is in a standard inflation state; acquiring X, wherein X is the actual length of a piston rod of the buffer extending out of the outer cylinder of the buffer; and judging to obtain the inflation state of the buffer according to the X0, the X and the characteristic parameters of the buffer. The method avoids the step of jacking the airplane by using the hydraulic jack in the prior art, is convenient and effective, is less limited by environmental factors, and can avoid potential risks in the prior art.
Description
Technical Field
The application belongs to the technical field of airplane detection, and particularly relates to an undercarriage air pressure detection method.
Background
Landing gear is an important part of an aircraft, is mainly used for absorbing impact load of the aircraft during landing or takeoff of the aircraft, and is a core part of the landing gear is a buffer. Currently, the buffer mostly adopts an oil-gas structure, and the structure thereof is as shown in fig. 2, including: an outer cylinder 1; one end of the piston rod 2 is arranged in the outer cylinder 1, is in sealing contact with the inner wall of the outer cylinder 1, and forms an oil cavity with the outer cylinder 1, and the other end of the piston rod is connected with the undercarriage wheel; the piston rod 2 can move along the axial direction of the outer cylinder 1, and a cavity is formed in the piston rod; the floating piston 3 is arranged in the cavity and is in sealing contact with the inner wall of the cavity, so that the cavity is divided into two sections, wherein one section is called a buffer cavity, and the other section is called an air cavity; the buffer cavity and the oil cavity are close to the oil cavity and are communicated with the oil cavity through a damping hole; the floating piston 3 can move axially in the cavity; the oil cavity is filled with hydraulic oil, and the gas cavity is filled with gas.
In the landing or taking-off process of the airplane, the airplane wheel of the undercarriage bears impact load, the piston rod 3 is pushed to move towards the outer cylinder 1 along the axial direction, the volume of the oil cavity is squeezed, hydraulic oil in the oil cavity enters the buffer cavity through the damping hole, the floating piston 3 is further pushed to move back to the outer cylinder 1, the air cavity is squeezed, and air in the air cavity is compressed. Wherein, a part of the impact load born by the landing gear wheels is consumed when hydraulic oil flows into the damping holes, and the other part of the impact load is stored in the gas cavity.
In order to ensure the safety of the takeoff and landing process of an airplane, the undercarriage needs to be periodically maintained, wherein the detection of the gas pressure in an undercarriage buffer is involved. This solution has the following drawbacks:
1) the hydraulic jack is used for jacking the airplane, so that time and labor are wasted;
2) under certain special conditions, the use of hydraulic jacks to jack off aircraft is difficult and may present risks, for example on a ship-borne surface, which greatly increase the difficulty and risks of jacking up the aircraft due to the frequent rolling of the ship.
Accordingly, a technical solution is desired to overcome or at least alleviate at least one of the above-mentioned drawbacks of the prior art.
Disclosure of Invention
It is an object of the present application to provide a landing gear bumper air pressure detection method that overcomes or mitigates at least one of the above-mentioned disadvantages.
The technical scheme of the application is as follows:
a landing gear bumper air pressure detection method, comprising:
obtaining P, wherein P is the pressure of a buffer air cavity;
obtaining T, wherein T is the internal King temperature of the air cavity of the buffer;
obtaining X0 according to P, T and characteristic parameters of the buffer, wherein X0 is the theoretical length of the piston rod extending out of the outer cylinder when the buffer is in a standard inflation state;
acquiring X, wherein X is the actual length of a piston rod of the buffer extending out of the outer cylinder of the buffer;
and judging the inflation state of the buffer according to X0 and X.
Optionally, obtaining X0 from P and T includes calculating from P as a function of T and X0.
Optionally, the characteristic parameters include N, L1, D1, D2, and VLiquid for treating urinary tract infection；
The functional relation is a theoretical functional relation:
P＝NRT/(πD1*D1*L1+πD2*D2*(L1-X0))/4-Vliquid for treating urinary tract infection)；
Wherein the content of the first and second substances,
n is the amount of gas substances in the gas cavity of the buffer under the standard inflation state of the buffer;
r is an ideal gas constant;
l1, the length of the damper piston rod;
d1, the diameter of the piston rod of the buffer;
d2, the diameter of the buffer outer cylinder;
Vliquid for treating urinary tract infectionThe volume of the buffer filled with hydraulic oil.
Optionally, the functional relation is one of a plurality of fitted functional relations;
a plurality of fitted functional relationships, comprising: f (X0)i,i＝1,2,3，……n；
P＝f(X0)iFrom TiFitting time reference data to obtain;
Tireference data of time passing through TiFrom a baseline experiment of time, TiThe reference experiment was carried out with the buffer in a standard inflated state and with a Ti temper in the buffer air cavity.
Optionally, the functional relationship is P ═ f (X0)kWherein, | TK-T|≤|Ti-T|，i＝1,2,3，……n。
Optionally, obtaining X0 from P and T, including obtaining X0 by consulting one of a plurality of pressure and extension maps;
multiple pressure and extension relationshipsA diagram, comprising: (P. X0)iA relational graph, i ═ 1,2,3, … … n; wherein the content of the first and second substances,
(P～X0)ithe relation graph is a P-X0 relation graph drawn according to the reference data at the time of Ti; the reference data for Ti were obtained by reference experiments for Ti, TiThe standard experiment is that the buffer is in a standard inflation state, and the open-air temperature in the air cavity of the buffer is TiUnder the conditions of (1).
Alternatively, X0 is derived from P and T for review (P X0)kThe relationship graph yields X0, where | Tk-T|≤|Ti-T|，i＝1,2,3，……n。
Alternatively, TiBaseline experimental data including: (P)ij，X0ij)，j＝1,2,3……m；TiBaseline experiments in (1) including:
a measurement step: pushing a buffer piston rod to move along the axial direction of the buffer outer cylinder to obtain a reference state of the buffer, and measuring P, X0 under the reference state;
a recording step: repeating the measuring step m times;
recording P obtained by the measurement step for the q-th time as PiqRecord X0 as X0 for the q-th measurement stepiqQ is 1,2,3 … … m; thus, the reference experimental data (P) at the time of Ti was obtainedij，X0ij)，j＝1,2,3……m。
Optionally, determining the inflation state of the buffer according to X0 and X includes:
step one, judging whether | X0-X | exceeds a preset threshold value;
and step two, if the | X0-X | does not exceed the preset threshold, the inflation state of the buffer is obtained as normal inflation pressure.
Optionally, in the second step, if | X0-X | exceeds the predetermined threshold, determining whether X0 is greater than X;
if X0 is larger than X, the inflation state of the buffer is obtained as that the inflation pressure is lower;
otherwise, the inflation state of the buffer is obtained as the inflation pressure is higher.
The application has at least the following beneficial technical effects: the method is used for judging the inflation state of the buffer based on data X which can be obtained by direct measurement and data X0 which can be obtained by direct measurement.
Drawings
FIG. 1 is a schematic view of a partial structure of a landing gear;
FIG. 2 is a cross-sectional view of area A of FIG. 1;
FIG. 3 is a schematic flow chart of a landing gear air pressure detection method of the present application;
FIG. 4 is a schematic flow chart illustrating a method for determining an inflation status of a bumper according to the landing gear air pressure detection method of the present application;
FIG. 5 is a graph of a detected air pressure P versus a desired protrusion X0 in accordance with one embodiment of the present application.
Wherein:
1-outer cylinder; 2-a piston rod; 3-a floating piston;
l1 — length of piston rod; d1-piston rod diameter; x1-the length of the air cavity along the axial direction of the piston rod; x2-length of the cushion chamber in the axial direction of the piston rod;
l2-length of outer barrel; d2-diameter of outer cylinder; y1-length of oil cavity in axial direction of outer cylinder; y2-the length of the piston rod in the axial direction of the inner cylinder part;
and measuring by X-to obtain the length of the piston rod extending out of the outer cylinder.
Detailed Description
In order to make the implementation objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the drawings in the embodiments of the present application. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are a subset of the embodiments in the present application and not all embodiments in the present application. The embodiments described below with reference to the drawings are exemplary and intended to be used for explaining the present application and should not be construed as limiting the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application. Embodiments of the present application will be described in detail below with reference to the accompanying drawings.
In the description of the present application, it is to be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are used merely for convenience in describing the present application and for simplifying the description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed in a particular orientation, and be operated, and therefore should not be construed as limiting the scope of the present application.
The present application is described in further detail below with reference to fig. 1 to 5.
A landing gear bumper air pressure detection method, comprising:
obtaining P, wherein P is the pressure of a buffer air cavity;
obtaining T, wherein T is the internal King temperature of the air cavity of the buffer;
obtaining X0 according to P, T and characteristic parameters of the buffer, wherein X0 is the theoretical length of the piston rod extending out of the outer cylinder when the buffer is in a standard inflation state;
acquiring X, wherein X is the actual length of a piston rod of the buffer extending out of the outer cylinder of the buffer;
and judging the inflation state of the buffer according to X0 and X.
The P, T, X can be obtained by direct measurement.
Further, obtaining X0 from P and T includes calculating from P and T and X0.
Further, the characteristic parameters of the buffer include: n, L1, D1, D2 and VLiquid for treating urinary tract infection；
The functional relation is a theoretical functional relation:
P＝NRT/(πD1*D1*L1+πD2*D2*(L1-X0))/4-Vliquid for treating urinary tract infection) (ii) a Wherein the content of the first and second substances,
n is the amount of gas substances in the gas cavity of the buffer under the standard inflation state of the buffer; r is an ideal gas constant; l1, the length of the damper piston rod; d1, the diameter of the piston rod of the buffer; d2, the diameter of the buffer outer cylinder; vLiquid for treating urinary tract infectionThe volume of the buffer filled with hydraulic oil.
The theoretical function relational expression is obtained based on the gas state equation that the volume of the hydraulic oil filled in the buffer has incompressibility and can meet engineering application, and the process is explained as follows:
V＝Vair conditioner-VSlow
＝πD1*D1*L1/4-(VLiquid for treating urinary tract infection-VOil)
＝πD1*D1*L1/4-VLiquid for treating urinary tract infection+VOil
＝πD1*D1*L1/4-VLiquid for treating urinary tract infection+πD2*D2*Y1/4
＝πD1*D1*L1/4-VLiquid for treating urinary tract infection+πD2*D2*(L2-Y2)/4
＝πD1*D1*L1/4-VLiquid for treating urinary tract infection+πD2*D2*(L1-X0)/4
＝(πD1*D1*L1+πD2*D2*(L1-X0))/4-VLiquid for treating urinary tract infection；
PV＝NRT；
P＝NRT/V
＝NRT/(πD1*D1*L1+πD2*D2*(L1-X0))/4-VLiquid for treating urinary tract infection) Wherein, in the step (A),
v, is the volume of the air cavity of the buffer;
n is the amount of gas substances in the gas cavity of the buffer under the standard inflation state of the buffer;
r is an ideal gas constant;
Vair conditionerThe volume of the cavity in the piston rod 2 of the buffer is shown;
VslowThe volume of the buffer cavity of the buffer;
Vliquid for treating urinary tract infectionA volume of hydraulic oil filled into the buffer;
VoilA volume of the bumper oil cavity;
d1, the diameter of the damper piston rod 2;
d2, which is the diameter of the damper outer cylinder 1;
l1, the length of the damper piston rod 2;
l2, which is the length of the damper outer cylinder 1;
y1, the length of the buffer oil chamber along the axial direction of the outer cylinder 1;
and Y2 is the length of the part, located in the buffer inner cylinder 1, of the buffer piston rod 2 along the axial direction.
In applying the above theoretical functional relation, for the related parameters, for a certain type of buffer, those skilled in the art can obtain the parameters by looking up the structural parameters of the buffer, or by direct measurement, or by other conceivable or commonly used means in the art. Experiments prove that the difference between X0 obtained according to the theoretical function relational expression and the actual is not more than 1 percent, and the technical application in the field can be met.
Further, the functional relation is one of a plurality of fitting functional relations; a plurality of fitted functional relationships, comprising: f (X0)i1,2,3, … … n; wherein, P ═ f (X0)iFrom TiFitting time reference data to obtain; t isiReference data of time passing through TiFrom a baseline experiment of time, TiThe standard experiment is that the buffer is in a standard inflation state, and the open-air temperature in the air cavity of the buffer is TiUnder the conditions of (1). ' Qiyi
The fitting function relation is obtained by directly fitting the reference data obtained by the reference experiment, and the accuracy of the fitting function relation can be ensured.
Further, the functional relation is P ═ f (X0)kWherein k ∈ (1, 2,3, … … n), and | Tk-T|≤|Ti-T |, i ═ 1,2,3, … … n. To this end, those skilled in the art will readily understand that P ═ f (X0)kFor one of a plurality of fitted functional relationships, which is represented by TkFitting of the reference data of time to obtain, TkAt Tii is the closest T of 1,2,3, … … n.
Further, the method can be used for preparing a novel materialObtaining X0 from P and T, including obtaining X0 by consulting one of a plurality of pressure and extension maps; a plurality of pressure and extension relationship maps, comprising: (P. X0)iA relational graph, i ═ 1,2,3, … … n; wherein, (P-X0)iThe relationship diagram is according to TiA P-X0 relation graph drawn by time reference data; t isiReference data of time passing through TiFrom a baseline experiment of time, TiThe standard experiment is that the buffer is in a standard inflation state, and the open-air temperature in the air cavity of the buffer is TiUnder the conditions of (1).
Further, X0 is obtained from P and T by reference (P. X0)kThe relationship graph yields X0, where k ∈ (1, 2,3, … … n), and | Tk-T|≤|Ti-T |, i ═ 1,2,3, … … n. In this regard, those skilled in the art will readily understand that (P. about. X0)kIs one of a plurality of pressure and extension relationship graphs, which is composed of TkThe time reference data is plotted, TkAt Tii is the closest T of 1,2,3, … … n.
Further, the reference experimental data at Ti include: (P)ij，X0ij)，j＝1,2,3……m；TiBaseline experiments in (1) including: a measurement step: pushing a buffer piston rod to move along the axial direction of the buffer outer cylinder to obtain a reference state of the buffer, and measuring P, X0 under the reference state; a recording step: repeating the measuring step m times; recording P obtained by the measurement step for the q-th time as PiqRecord X0 as X0 for the q-th measurement stepiqQ is 1,2,3 … … m; thereby obtaining TiReference experimental data (P) of (C)ij，X0ij)，j＝1,2,3……m。
Further, determining the inflation state of the buffer according to X0 and X includes: step one, judging whether | X0-X | exceeds a preset threshold value; and step two, if the | X0-X | does not exceed the preset threshold, the inflation state of the buffer is obtained as normal inflation pressure.
Further, in the second step, if | X0-X | exceeds the predetermined threshold, determining whether X0 is greater than X; if X0 is larger than X, the inflation state of the buffer is obtained as that the inflation pressure is lower; otherwise, the inflation state of the buffer is obtained as the inflation pressure is higher.
As a more specific embodiment disclosed in the present application, reference is made to the following:
the measurement results show that the P of the airplane buffer under a certain state is 3.0MPa, and T and X are 290mm,
looking up the (P-X0) k-relation graph according to T, as shown in fig. 5, obtaining X0 ═ 300 mm;
if the predetermined threshold is set to 5mm, the state of inflation of the buffer is obtained as a low inflation pressure.
The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (4)
1. A landing gear bumper air pressure detection method, comprising:
obtaining P, wherein the P is the pressure of a buffer air cavity;
obtaining T, wherein the T is the internal King temperature of the buffer air cavity; obtaining X0 according to the characteristic parameters of the P, the T and the buffer, wherein X0 is the theoretical length of the piston rod (2) extending out of the outer cylinder (1) when the buffer is in a standard inflation state;
obtaining X, wherein the X is the actual length of a piston rod (2) of the buffer extending out of an outer cylinder (1) of the buffer;
judging to obtain the inflation state of the buffer according to the X0 and the X;
obtaining X0 according to the P and the T, including calculating according to a functional relation of the P and the T and the X0;
the functional relation is one of a plurality of fitting functional relations;
a plurality of said fitted functional relationships comprising: f (X0)i,i＝1,2,3，……n；
F (X0)iFrom TiFitting time reference data to obtain;
the T isiReference data of time passing through TiObtained from a standard experiment of time, the TiThe time reference experiment is that the buffer is in a standard inflation state, and the open-air temperature in the air cavity of the buffer is TiUnder the conditions of (a);
the functional relation is P ═ f (X0)kFrom TkFitting the time reference data to obtain k ∈ (1, 2,3, … … n) | TK-T|≤|Ti-T|，i＝1,2,3，……n。
2. The detection method according to claim 1,
the T isiBaseline experimental data including: (P)ij，X0ij)，j＝1,2,3……m；
The T isiBaseline experiments in (1) including:
a measurement step: pushing the buffer piston rod (2) to move along the axial direction of the buffer outer cylinder (1), obtaining a reference state of the buffer, and measuring P, X0 under the reference state;
a recording step: repeating the measuring step m times;
recording P obtained by performing the measuring step for the q-th time as PiqRecording X0 as X0, the result of said measurement step being performed q timesiq，q1,2,3 … … m; thereby obtaining said TiReference experimental data (P) of (C)ij，X0ij)，j＝1,2,3……m。
3. The method of claim 1, wherein the determining the inflation status of the buffer according to the X0 and the X comprises:
step one, judging whether | X0-X | exceeds a preset threshold value;
and step two, if the | X0-X | does not exceed the preset threshold, the inflation state of the buffer is obtained to be normal inflation pressure.
4. The detection method according to claim 3,
in the second step, if the | X0-X | exceeds a preset threshold, judging whether X0 is larger than X;
if the X0 is larger than X, the inflation state of the buffer is obtained as that the inflation pressure is lower; otherwise, the inflation state of the buffer is obtained as the inflation pressure is higher.
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