Auxiliary Power Unit Vibration Damping System and Optimization Method for a Large Wide-Body Airliner

Abstract

This application belongs to the technical field of the configuration or installation of power devices or propulsion transmission devices in aircraft, and particularly relates to an auxiliary power unit vibration damping system and an optimization method for a large wide-body airliner. The vibration damping system includes: an auxiliary power unit, a plurality of shock absorbers, and a plurality of tie rods; wherein, each shock absorber includes: a housing, a shaft body, and an elastomer. The shaft body includes a damping end and a connecting end, and the damping end has a mounting disc; the elastomer has a central hole, and the inner diameter of the middle part of the central hole becomes larger to form a mounting cavity, and the mounting disc is sleeved in the mounting cavity of the elastomer; the housing has a cavity, and the surface of the housing has a through hole. The damping end of the shaft body sleeved with the elastomer is installed inside the housing, and the connecting end of the shaft body is placed outside the housing through the through hole of the housing; the plurality of shock absorbers are installed on an auxiliary power unit through the connecting ends of the shaft bodies, and the housing of each shock absorber is connected to the airframe through at least one tie rod, so that the auxiliary power unit is fixedly installed on the airframe.

Description

Technical Field

[0001] This application belongs to the technical field of the configuration or installation of power devices or propulsion transmission devices in aircraft, and particularly relates to a vibration damping system and optimization method for an auxiliary power unit of a large wide-body airliner. Background Art

[0002] The auxiliary power unit (APU) of a large wide-body airliner is generally installed at the tail of the aircraft, serving as the second power source of the aircraft to provide electricity and bleed air, and to start the main engine on the ground. Since the vibration of the aircraft fuselage will have an adverse impact on the operation and reliability of the APU, and the vibration of the APU will also be transmitted to the aircraft fuselage. Therefore, it is necessary to install the APU with vibration damping. Summary of the Invention

[0003] To solve the above problems, this application provides a vibration damping system for an auxiliary power unit of a large wide-body airliner, including:

[0004] An auxiliary power unit, a plurality of shock absorbers, and a plurality of tie rods;

[0005] Among them, the shock absorber includes: a housing, a shaft body, and an elastic body. Among them, the shaft body includes a vibration damping end and a connection end. The vibration damping end has an installation disc; the elastic body has a central hole, and the inner diameter of the middle part of the central hole becomes larger to form an installation cavity, and the installation disc is sleeved in the installation cavity of the elastic body; the housing has a cavity, and the surface of the housing has a through hole. The vibration damping end of the shaft body sleeved with the elastic body is installed inside the housing, and the connection end of the shaft body is placed outside the housing through the through hole of the housing;

[0006] A plurality of shock absorbers are installed on the auxiliary power unit through the connection ends of the shaft bodies, and the housing of each shock absorber is connected to the fuselage through at least one tie rod, so that the auxiliary power unit is fixedly installed on the fuselage.

[0007] Preferably, the auxiliary power unit has a left front mounting section, a right front mounting section, a left rear mounting section, and a right rear mounting section, and each mounting section is respectively installed with a shock absorber.

[0008] Preferably, the shock absorber is connected to the auxiliary power unit through a mounting base. One end of the mounting base has a spherical mounting head, and the other end has a flange mounting plate. The spherical mounting head has a tapered through hole. The connection end of the shaft body has a tapered section and a screw section. The tapered surface of the tapered section fits with the tapered surface of the tapered through hole, and a locknut is connected to the screw section to fix the connection end of the shaft body to the mounting base.

[0009] Preferably, both the elastic body and the cavity of the housing are cylindrical in shape, and a plurality of axially arranged grooves are circumferentially distributed on the outer cylindrical surface of the elastic body to provide a deformation space for the elastic body.

[0010] Preferably, the housing is provided with small holes at the groove positions for inserting the filling bodies into the grooves, and filling bodies with different volumes and different elastic moduli are filled to adjust the radial stiffness of the shock absorber.

[0011] Preferably, the housing includes an outer shell and a packaging bottom plate. The outer shell is a cylindrical barrel with one end open, and the inner surface at the opening has internal threads. The packaging bottom plate has external threads, and the packaging bottom plate is threadedly connected to the outer shell to form the cavity in the shape of a cylinder. By changing the screwing-in amount of the packaging bottom plate, the elastic body is compressed, and thus the axial stiffness of the shock absorber is adjusted.

[0012] An optimization method for the vibration damping system of an auxiliary power unit of a large wide-body airliner, which is used to optimize the vibration damping system of the auxiliary power unit of a large wide-body airliner. The method includes:

[0013] Step S1: Determine the static resultant force of each mounting node according to the gravity of the auxiliary power unit, and determine the dynamic resultant force of each mounting node according to the gravity and the load spectrum of the auxiliary power unit;

[0014] Step S2: Determine the number of tie rods, the installation angle of the tie rods, and the installation angle of the shock absorber for each mounting node according to the static resultant force and the dynamic resultant force;

[0015] Step S3: Establish a three-dimensional mechanical model of the installation angle, the number of tie rods, and the installation angle of the tie rods of each shock absorber;

[0016] Step S4: Combining the best shock absorption direction of the shock absorber, with the minimum vibration transfer rate of the auxiliary power unit vibration damping system as the optimization goal, use the genetic algorithm to optimize the installation angle of the shock absorber.

[0017] Preferably, in step S4, the genetic algorithm is also used to optimize the number of tie rods and the installation angle of the tie rods.

[0018] Preferably, based on the three-dimensional mechanical model, obtain the vibration frequency spectrum of each shock absorber, and adjust the axial and radial stiffnesses of the shock absorber based on the vibration frequency spectrum.

[0019] The advantages of the present application include: The vibration damping system provided by the present application can effectively suppress the vibration of the auxiliary power unit, reduce the resonance peak of the device, and improve the vibration damping efficiency.

[0020] Based on the vibration excitation direction of the auxiliary power unit, combined with the best shock absorption direction of the shock absorber, the present application optimizes the vibration of the system by adjusting the installation angle of the shock absorber. After the optimization is completed, the axial and radial stiffnesses of the shock absorber are adjusted to further optimize the vibration of the system.

[0021] The shock absorber of the present application has the function of adjusting the axial and radial stiffnesses. After the installation angle of the shock absorber is determined, the stiffness can be adjusted based on the vibration frequency spectrum or test data to reduce the resonance peak and improve the vibration damping efficiency. Brief Description of the Drawings

[0022] Figure 1 It is a schematic diagram showing the connection of multiple shock absorbers and multiple tie rods in a preferred embodiment of the present application.

[0023] Figure 2 It is a schematic diagram of the front left mounting joint shock absorber in a preferred embodiment of the present application.

[0024] Figure 3 It is a half-sectional view of the front left mounting joint shock absorber in a preferred embodiment of the present application.

[0025] Figure 4 It is a schematic diagram of the shaft body in a preferred embodiment of the present application.

[0026] Figure 5 It is a schematic diagram of the outer shell of the front left mounting joint shock absorber in a preferred embodiment of the present application.

[0027] Figure 6 It is a schematic diagram of the encapsulation bottom plate of the front left mounting joint shock absorber in a preferred embodiment of the present application.

[0028] Figure 7 It is a schematic diagram of the mounting base of the front left mounting joint shock absorber in a preferred embodiment of the present application. Detailed Description of the Embodiments

[0029] To make the technical solutions and their advantages of the present application clearer, the technical solutions of the present application will be further described clearly and completely below in conjunction with the drawings. It can be understood that the specific embodiments described herein are only part of the embodiments of the present application, which are only used to explain the present application and not to limit the present application. It should be noted that for the convenience of description, only the parts related to the present application are shown in the drawings, and other related parts can refer to the general design. Without conflict, the embodiments and the technical features in the embodiments of the present application can be combined with each other to obtain new embodiments.

[0030] In addition, it should be noted that unless otherwise clearly specified and limited, the terms "mounted", "connected", "coupled" and other similar terms used in the description of the present application should be understood in a broad sense. For example, the connection can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and can also be the communication inside two components. Those skilled in the art can understand their specific meanings in the present application according to the specific situation.

[0031] The present application provides a vibration damping system for an auxiliary power unit of a large wide-body airliner, as Figures 1-7 shown, including:

[0032] Auxiliary power unit, multiple shock absorbers, and multiple tie rods;

[0033] Among them, the shock absorbers are divided into a front left mounting joint shock absorber assembly 1, a front right mounting joint shock absorber assembly 2, a rear left mounting joint shock absorber assembly 3, and a rear right mounting joint shock absorber assembly 4. The entire shock absorption system is connected to the body through 8 tie rods. The bottoms of the four shock absorber assemblies are respectively connected to the four mounting joints of the APU. There are rubber bodies with the same configuration inside the shock absorber assemblies, serving as the elastic bodies 152 for shock absorption. Taking the front left mounting joint shock absorber assembly 1 as an example, it includes: a housing, a shaft body 151, and an elastic body 152. Among them, the shaft body 151 includes a shock absorption end and a connection end. The shock absorption end has a mounting disc; the elastic body 152 has a central hole, and the inner diameter in the middle of the central hole becomes larger to form a mounting cavity. The mounting disc is sleeved in the mounting cavity of the elastic body 152; the housing has a cavity, and there are through holes on the surface of the housing. The shock absorption end of the shaft body 151 sleeved with the elastic body 152 is installed inside the housing, and the connection end of the shaft body 151 is placed outside the housing through the through holes of the housing;

[0034] Among them, in one solution, the housing includes an outer shell 11, a packaging bottom plate 12, a stop gasket 13, and packaging bolts 14. The outer shell 11 and the packaging bottom plate 12 form a cavity. A core shaft 15 is located in the middle of the cavity. The outer shell 11 has flange screw holes, and the packaging bottom plate 12 has a central opening 121 and flange through holes 122. The central opening 121 is used to pass through the shaft body 151. The outer shell 11 and the packaging bottom plate 12 are connected into one body by 4 groups of packaging bolts 14 and stop gaskets 13. The outer shell 11 has three pairs of mounting ears respectively connected to three external tie rods, and the other ends of the tie rods are connected to the body structure. In another solution, the housing includes the outer shell 11 and the packaging bottom plate 12. The outer shell 11 is a cylindrical barrel with one end open, and the inner surface at the opening has internal threads. The packaging bottom plate 12 has external threads. The packaging bottom plate 12 is threadedly connected to the outer shell 11 to form the cavity in the shape of a cylinder. By changing the screwing-in amount of the packaging bottom plate 12, the elastic body 152 is compressed, thereby adjusting the stiffness of the shock absorber in the axial direction.

[0035] Multiple shock absorbers are installed on an auxiliary power unit through the connection ends of the shaft bodies 151. The housing of each shock absorber is connected to the body through at least one tie rod, so that the auxiliary power unit is fixedly installed on the body.

[0036] Preferably, the auxiliary power unit has a front left mounting joint, a front right mounting joint, a rear left mounting joint, and a rear right mounting joint, and each mounting joint installs a shock absorber respectively.

[0037] Preferably, the shock absorber is connected to the auxiliary power unit through a mounting base 16. One end of the mounting base 16 has a spherical mounting head 162, and the other end has a flange mounting plate 161. The spherical mounting head 162 has a tapered through hole 163, and there is a rotation-preventing boss 164 at the edge of the tapered through hole 163.

[0038] The connecting end of the shaft body 151 has a tapered section 1513 and a screw section 1511. The tapered surface of the tapered section 1513 fits with the tapered surface of the tapered through hole 163. A locknut 17 is connected to the screw section 1511 to fix the connecting end of the shaft body 151 to the mounting base 16. The screw section 1511 also has a perforation 1512 for installing a pin to prevent the locknut 17 from rotating. During use, relative displacement occurs between the mounting base 16 and the housing 11 to cause the elastomer 152 in the mandrel 15 to be squeezed and deformed, thereby playing a role in vibration isolation.

[0039] Preferably, both the elastomer 152 and the cavity of the housing are cylindrical in shape. A plurality of axially arranged grooves 153 are circumferentially distributed on the outer cylindrical surface of the elastomer 152 to provide a deformation space for the elastomer 152.

[0040] Preferably, the housing is provided with small holes at the positions of the grooves 153 for inserting filling bodies into the grooves 153. Filling bodies with different volumes and different elastic moduli are filled to adjust the radial stiffness of the shock absorber.

[0041] An optimization method for the vibration damping system of an auxiliary power unit of a large wide-body airliner is used to optimize the vibration damping system of the auxiliary power unit of a large wide-body airliner. The method includes:

[0042] Step S1: Determine the static resultant force of each mounting node according to the gravity of the auxiliary power unit, and determine the dynamic resultant force of each mounting node according to the gravity and the load spectrum of the auxiliary power unit.

[0043] Step S2: Determine the number of tie rods, the installation angle of the tie rods, and the installation angle of the shock absorbers for each mounting node according to the static resultant force and the dynamic resultant force.

[0044] Step S3: Establish a three-dimensional mechanical model of the installation angle, the number of tie rods, and the installation angle of the tie rods for each shock absorber.

[0045] Step S4: Combining the best vibration damping direction of the shock absorber, with the minimum vibration transmission ratio of the vibration damping system of the auxiliary power unit as the optimization goal, use the genetic algorithm to optimize the installation angle of the shock absorber.

[0046] Preferably, the genetic algorithm is also used in step S4 to optimize the number of tie rods and the installation angle of the tie rods.

[0047] Preferably, based on the three-dimensional mechanical model, the vibration frequency spectrum of each shock absorber is obtained, and the axial and radial stiffnesses of the shock absorber are adjusted based on the vibration frequency spectrum.

[0048] The advantages of the present application include: The vibration damping system provided by the present application can effectively suppress the vibration of the auxiliary power unit, reduce the resonance peak of the device, and improve the vibration damping efficiency.

[0049] Based on the vibration excitation direction of the auxiliary power unit and combined with the optimal vibration damping direction of the shock absorber, the vibration of the system is optimized by adjusting the installation angle of the shock absorber. After the optimization is completed, the stiffness of the shock absorber in the axial and radial directions is adjusted to further optimize the vibration of the system.

[0050] The shock absorber of the present application has the function of adjusting the stiffness in the axial and radial directions. After the installation angle of the shock absorber is determined, it can adjust the stiffness based on the vibration spectrum or test data to reduce the resonance peak and improve the vibration damping efficiency.

[0051] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for optimizing the vibration reduction system of an auxiliary power unit of a large wide-body passenger aircraft, characterized in that: Used to optimize the vibration reduction system of the auxiliary power unit of a large wide-body passenger aircraft, the vibration reduction system of the auxiliary power unit of a large wide-body passenger aircraft comprises: an auxiliary power unit, a plurality of shock absorbers and a plurality of tie rods; The vibration damper comprises: a housing, a shaft (151) and an elastic body (152), wherein the shaft (151) comprises a vibration damping end and a connecting end, and the vibration damping end has a mounting disc; the elastic body (152) has a central hole, the inner diameter of the middle of the central hole is enlarged to form a mounting cavity, and the mounting disc is sleeved in the mounting cavity of the elastic body (152); the housing has a cavity, and the surface of the housing has a through hole, the vibration damping end of the shaft (151) sleeved with the elastic body (152) is installed inside the housing, and the connecting end of the shaft (151) is placed outside the housing through the housing through hole; A plurality of shock absorbers are mounted on the auxiliary power unit via the connection end of the shaft body (151), and the housing of each shock absorber is connected to the machine body via at least one tie rod; The elastic body (152) and the housing cavity of the shell are both cylindrical in shape, and a plurality of axially arranged grooves (153) are circumferentially distributed on the outer cylindrical surface of the elastic body (152) to provide a rubber deformation space and adjust the radial stiffness of the shock absorber; The housing is provided with a small hole at the position of the groove (153) for inserting a filling body into the groove (153), and the filling body with different volumes and different elastic moduli is filled to adjust the radial stiffness of the shock absorber; The housing comprises an outer shell (11) and a packaging bottom plate (12); the outer shell (11) is a cylindrical body with an opening at one end, the inner surface of the opening having an internal thread, the packaging bottom plate (12) having an external thread, the packaging bottom plate (12) and the outer shell (11) being threadedly connected to form the cylindrical cavity; the screwing amount of the packaging bottom plate (12) is changed to compress the elastic body (152), thereby adjusting the axial stiffness of the shock absorber; The method comprises: Step S1: determining the static resultant force of each installation node according to the gravity of the auxiliary power device, and determining the dynamic resultant force of each installation node according to the gravity and the load spectrum of the auxiliary power device; Step S2: determining the number of tie rods, tie rod installation angles, and shock absorber installation angles of each installation section according to the static resultant force and the dynamic resultant force; Step S3: establishing a three-dimensional mechanical model of the installation angle, the number of tie rods and the installation angle of the tie rods of each shock absorber; Step S4: combining the optimal vibration reduction direction of the shock absorber, according to the vibration excitation direction of the auxiliary power unit, taking the minimum vibration transmission rate of the auxiliary power unit vibration reduction system as the optimization goal, and using a genetic algorithm to optimize the installation angle of the shock absorber; A vibration spectrum of each shock absorber is obtained based on the three-dimensional mechanical model, and the axial and radial stiffness of the shock absorber is adjusted based on the vibration spectrum.

2. The method for optimizing the vibration reduction system of the auxiliary power unit of a large wide-body passenger aircraft according to claim 1, characterized in that: In step S4, a genetic algorithm is also used to optimize the number of tie rods and the installation angle of the tie rods.

3. The method for optimizing the vibration reduction system of the auxiliary power unit of a large wide-body passenger aircraft according to claim 1, characterized in that: The auxiliary power unit comprises a left front mounting section, a right front mounting section, a left rear mounting section and a right rear mounting section, and each mounting section is respectively provided with a shock absorber.

4. The method for optimizing the vibration reduction system of the auxiliary power unit of a large wide-body passenger aircraft according to claim 2, characterized in that: The shock absorbers on the left front side and the right front side are connected to the auxiliary power unit via a mounting base (16); one end of the mounting base (16) has a spherical mounting head (162) and the other end has a flange mounting plate (161); the spherical mounting head (162) has a conical through hole (163) parallel to the plate surface of the flange mounting plate (161); the connecting end of the shaft body (151) has a conical section and a screw section; the conical surface of the conical section fits the conical surface of the conical through hole (163); the screw section is connected to a locking bolt (17) to fix the connecting end of the shaft body (151) to the mounting base (16).

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