High-frequency double-frequency-modulation vibration absorber for main noise reduction control of helicopter

Abstract

The utility model discloses a high-frequency double-frequency-modulation vibration absorber for main noise reduction control of a helicopter. The high-frequency double-frequency-modulation vibration absorber comprises a spring support assembly and a mass piece. The spring frame assembly comprises two cantilever beam spring frames which are symmetrically installed, the installation end face of each cantilever beam spring frame is provided with arc grooves with the same aperture, the two sides of the oppositely-arranged installation end faces are provided with installation lugs, and the two cantilever beam spring frames wrap the main reduction supporting rod in the mode that the installation end faces are oppositely arranged; mounting lugs on the same sides of the two cantilever beam spring brackets are fixedly connected through first connecting bolts, so that the spring bracket assembly is fixedly mounted on the main reducing support rod; a kidney-shaped groove is formed in the upper end face of each cantilever beam spring support of the spring support assembly, and at least one mass piece is installed on the kidney-shaped grooves of the cantilever beam spring supports in a sliding mode through second connecting bolts. According to the technical scheme, the problems that an existing passive vibration absorber can only meet the requirement for low-frequency vibration reduction and noise reduction below 200 Hz generally, the vibration reduction direction is single, an original structure needs to be modified, and the design difficulty is large are solved.

Description

Technical Field

[0001] The utility model relates to, but is not limited to, the technical field of noise reduction inside a helicopter cabin, and particularly relates to a high-frequency dual-frequency vibration absorber for helicopter main reduction noise control. Background Art

[0002] Vibration absorbers include passive and active configurations. Currently, passive vibration absorbers are commonly used on helicopters to reduce low-frequency vibrations caused by rotor loads, and are generally installed on the cabin floor (for example, a variable-frequency dynamic vibration absorber for a helicopter cabin floor, CN201910938043.7) or on the fuselage frame beam, and their natural frequencies are generally within 100 Hz. In the aircraft field, vibration absorbers installed on the wall panels can be seen (for example, Sun Zhaohui et al., Research on the use of dynamic vibration absorbers for aircraft wall panel vibration reduction and noise reduction, Acta Aeronautica et Astronautica Sinica, 1993, 14(10): B506 - B509), which can be used to suppress the vibration radiation noise of the aircraft wall panel, and the noise reduction frequency reaches 100 Hz; in addition, a dynamic vibration absorber is installed between the aircraft engine and the fuselage (Robert H.B..Aircraft cabin noise reduction system with tuned vibration absorbers, USP3490556, 1970.), which suppresses the transmission of engine harmonic vibrations to the fuselage, thereby reducing the engine noise inside the cabin.

[0003] Problems and disadvantages of the prior art: Since the existing vibration absorbers mainly target the vibration reduction and noise reduction requirements below 200 Hz, the equivalent stiffness of the above structures is small, it is difficult to adjust the natural frequency to above 1000 Hz, and the vibration reduction direction is single; in addition, due to the installation position limitation, it is generally necessary to modify the original structure, which increases the design difficulty and even induces new safety problems. Summary of the Utility Model

[0004] The purpose of the present utility model is: To solve the above problems, the embodiments of the present utility model provide a high-frequency dual-frequency vibration absorber for helicopter main reduction noise control, so as to solve the problems that the existing passive vibration absorbers can usually only meet the low-frequency vibration reduction and noise reduction requirements below 200 Hz, and the vibration reduction direction is single, as well as the problem that it is necessary to modify the original main reduction strut structure, resulting in a relatively large design difficulty.

[0005] The technical solution of the present utility model is: The embodiments of the present utility model provide a high-frequency dual-frequency vibration absorber for helicopter main reduction noise control, including: a spring frame assembly and a mass piece 2;

[0006] Among them, the spring frame assembly includes: two cantilever beam spring frames 1 symmetrically installed. Each cantilever beam spring frame 1 has an arc groove 9 with the same aperture on its installation end face, and there are installation lugs on both sides of the opposite installation end faces. By arranging the two cantilever beam spring frames 1 with their installation end faces opposite to each other and wrapping them around the main reduction strut, and using the first connecting bolt 4 to fixedly connect the installation lugs on the same side of the two cantilever beam spring frames 1, the spring frame assembly is fixedly installed on the main reduction strut;

[0007] On the upper end face of each cantilever beam spring frame 1 of the spring frame assembly, a waist-shaped groove 5 is provided, and at least one mass piece 2 is slidably installed on the waist-shaped groove 5 of the cantilever beam spring frame 1 by using the second connecting bolt 3.

[0008] Optionally, in the high-frequency dual-tuned vibration absorber for helicopter main reduction noise control as described above,

[0009] The position of the mass piece 2 installed on each cantilever beam spring frame 1 slides within the waist-shaped groove, which is used to change the overall stiffness of the high-frequency dual-tuned vibration absorber.

[0010] Optionally, in the high-frequency dual-tuned vibration absorber for helicopter main reduction noise control as described above,

[0011] By changing the number of mass pieces 2 installed on each cantilever beam spring frame 1, the noise reduction frequency range of the vibration absorber is adjusted.

[0012] Optionally, in the high-frequency dual-tuned vibration absorber for helicopter main reduction noise control as described above,

[0013] The diameter of the arc groove 9 of each cantilever beam spring frame 1 of the spring frame assembly is the same as the diameter of the main reduction strut, and the circumference of the arc groove 9 is less than half of the circumference of the main reduction strut.

[0014] Optionally, in the high-frequency dual-tuned vibration absorber for helicopter main reduction noise control as described above,

[0015] In each cantilever beam spring frame 1, the waist-shaped groove 5 for the slidable installation of the mass piece 2 is arranged along the symmetry axis direction of this cantilever beam spring frame 1, and the shortest distance between the end of the waist-shaped groove 5 close to the main reduction strut and the arc groove 9 of this cantilever beam spring frame 1 is greater than the radius of the mass piece 2.

[0016] Optionally, in the high-frequency dual-tuned vibration absorber for helicopter main reduction noise control as described above,

[0017] On the side wall of each cantilever beam spring frame 1, a plurality of square holes with the same size are provided, penetrating the side wall of the cantilever beam spring frame 1.

[0018] The beneficial effects of the present utility model are as follows: The embodiment of the present utility model provides a high-frequency dual-frequency vibration absorber for helicopter main reduction noise control. In order to improve the structural stiffness while minimizing the structural weight as much as possible, a hollowed-out cantilever beam-like structure is selected as the spring frame structure of the high-frequency dual-frequency vibration absorber, that is, the cantilever beam spring frame 1, and a waist-shaped groove is opened in the middle of the spring frame 1 so that the mass piece 2 can be slidably installed; the high-frequency dual-frequency vibration absorber provided by the embodiment of the present utility model can achieve two aspects of frequency modulation methods: on the one hand, by sliding the position of the mass piece 2 in the waist-shaped groove 5, the overall stiffness of the structure is changed; on the other hand, by changing the number of the mass pieces 2, the noise reduction frequency range of the vibration absorber can be adjusted. Therefore, by using the high-frequency dual-frequency vibration absorber provided by the embodiment of the present utility model, by selecting the appropriate position of the mass piece 2 and the number of the mass pieces 2, high-frequency vibration reduction from the main reducer to the fuselage can be achieved without damaging the strut structure and meeting the weight requirements, and further, the control of high-frequency harmonic noise generated by the meshing of the helicopter main reduction gears can be realized. The high-frequency dual-frequency vibration absorber provided by the embodiment of the present utility model has the following beneficial effects:

[0019] First, the main body structure can be integrally processed without splicing, effectively avoiding problems such as easy decomposition at the interface caused by multiple materials and difficult processing due to complex structure, and it is easy to install without damaging the structure of the main reduction strut;

[0020] Second, the thickness of the cantilever beam spring frame 1 designed in the embodiment of the present utility model is relatively large, effectively improving the structural stiffness, so that high-frequency noise reduction can be achieved;

[0021] Third, the high-frequency dual-frequency vibration absorber provided by the embodiment of the present utility model has two frequency modulation methods of stiffness frequency modulation and mass frequency modulation at the same time, and the frequency modulation is convenient and easy to achieve frequency modulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings are used to provide a further understanding of the technical solutions of the present utility model, and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solutions of the present utility model, and do not constitute a limitation to the technical solutions of the present utility model.

[0023] Figure 1 It is a schematic diagram of the overall structure of the high-frequency dual-frequency vibration absorber for helicopter main reduction noise control of the present utility model;

[0024] Figure 2 is Figure 1 A schematic diagram of the structure of the cantilever beam spring frame in the high-frequency dual-frequency vibration absorber for helicopter main reduction noise control provided by the shown embodiment;

[0025] Figure 3 is Figure 1Schematic diagram of the structure of the middle mass plate of the high-frequency dual-frequency vibration absorber for helicopter main reduction noise control provided by the illustrated embodiment;

[0026] Figure 4 Schematic diagram of the installation form of the high-frequency dual-frequency vibration absorber for helicopter main reduction noise control provided by the embodiment of the present invention on the main reduction support rod; Figure a shows the installation along the x direction of the main reduction support rod, and Figure b shows the installation along the y direction of the main reduction support rod;

[0027] Figure 5 Schematic diagram of the installation of the vibration absorber state 1 of the high-frequency dual-frequency vibration absorber provided by the embodiment of the present invention;

[0028] Figure 6 is Figure 5 Schematic diagram of the vibration absorption effect of the illustrated high-frequency dual-frequency vibration absorber at the simulation-vibration absorption frequency point and test-vibration absorption frequency point in the vibration absorber state 1; Figure a shows the vibration absorption effect of the high-frequency dual-frequency vibration absorber at the simulation-vibration absorption frequency point of 1162 Hz in the vibration absorber state 1, and Figure b shows the vibration absorption effect of the high-frequency dual-frequency vibration absorber at the test-vibration absorption frequency point of 1107 Hz in the vibration absorber state 1;

[0029] Figure 7 Schematic diagram of the installation of the vibration absorber state 2 of the high-frequency dual-frequency vibration absorber provided by the embodiment of the present invention;

[0030] Figure 8 is Figure 7 Schematic diagram of the vibration absorption effect of the illustrated high-frequency dual-frequency vibration absorber at the simulation-vibration absorption frequency point and test-vibration absorption frequency point in the vibration absorber state 2; Figure a shows the vibration absorption effect of the high-frequency dual-frequency vibration absorber at the simulation-vibration absorption frequency point of 937 Hz in the vibration absorber state 2, and Figure b shows the vibration absorption effect of the high-frequency dual-frequency vibration absorber at the test-vibration absorption frequency point of 950 Hz in the vibration absorber state 2;

[0031] Figure 9 Schematic diagram of the installation of the vibration absorber state 3 of the high-frequency dual-frequency vibration absorber provided by the embodiment of the present invention;

[0032] Figure 10 is Figure 9 Schematic diagram of the vibration absorption effect of the illustrated high-frequency dual-frequency vibration absorber at the simulation-vibration absorption frequency point of 1090 Hz in the vibration absorber state 3;

[0033] Figure 11 Schematic diagram of the installation of the vibration absorber state 4 of the high-frequency dual-frequency vibration absorber provided by the embodiment of the present invention;

[0034] Figure 12 is Figure 11 Schematic diagram of the vibration absorption effect of the illustrated high-frequency dual-frequency vibration absorber at the simulation-vibration absorption frequency point of 1441 Hz in the vibration absorber state 4;

[0035] Figure 13 For Figure 7 The schematic diagram of the vibration absorption effect of the high-frequency dual-frequency vibration absorber in the absorber state 5 at the vibration absorption frequency point of 937 Hz as shown Specific implementation manners

[0036] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention, and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present invention, and do not constitute a limitation to the technical solution of the present invention

[0037] As described in the above background art, currently passive vibration absorbers are usually used on helicopters to reduce the low-frequency vibration caused by the rotor load; and it is also described that the existing passive vibration absorbers generally have the following disadvantages

[0038] On the one hand, since the existing vibration absorbers mainly target the vibration reduction and noise reduction requirements below 200 Hz, the equivalent stiffness of the above structure is small, it is difficult to adjust the natural frequency above 1000 Hz, and the vibration reduction direction is single

[0039] On the other hand, due to the installation position limitation, it is generally necessary to modify the original structure, which increases the design difficulty and even induces new safety problems

[0040] In view of the above problems, the embodiment of the present invention provides a high-frequency dual-frequency vibration absorber for helicopter main reduction noise control, specifically a passive vibration absorber installed on the strut, which can realize noise reduction in the helicopter cabin; this high-frequency vibration absorber can suppress the high-frequency harmonic noise generated by the meshing of the helicopter main reduction gears without changing the main reduction strut, and the installation frequency is adjustable, and it can solve the problem of excessive main reduction noise in the existing helicopter cabin with a small weight

[0041] The present invention provides several specific embodiments that can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments

[0042] The embodiment of the present invention provides a high-frequency dual-frequency vibration absorber for helicopter main reduction noise control. This high-frequency dual-frequency vibration absorber is installed on the main reduction strut, and by suppressing the vibration transfer rate transmitted from the main reducer to the bottom of the strut, the structure-borne sound transmitted from the main reducer to the cabin is reduced. This high-frequency dual-frequency vibration absorber is processed and manufactured with a single material, and provides two frequency modulation forms: stiffness frequency modulation and mass frequency modulation

[0043] Figure 1 It is the overall structure schematic diagram of the high-frequency dual-frequency vibration absorber for helicopter main reduction noise control of the present invention Figure 2 For Figure 1Schematic diagram of the middle cantilever beam spring frame of the high-frequency dual-frequency vibration absorber for helicopter main reduction noise control provided by the illustrated embodiment Figure 3 is Figure 1 Schematic diagram of the middle mass piece of the high-frequency dual-frequency vibration absorber for helicopter main reduction noise control provided by the illustrated embodiment. As Figures 1 to 3 shown, the high-frequency dual-frequency vibration absorber for helicopter main reduction noise control provided by the embodiment of the present utility model may include: a spring frame assembly and a mass piece 2

[0044] As Figure 1 and Figure 2 shown, the spring frame assembly in the embodiment of the present utility model includes: 2 symmetrically installed cantilever beam spring frames 1. An arc groove 9 with the same aperture is provided on the installation end surface of each cantilever beam spring frame 1, and installation lugs are provided on both sides of the opposite installation end surfaces. By wrapping the 2 cantilever beam spring frames 1 in a form with the installation end surfaces facing each other around the main reduction support rod, and using the first connecting bolt 4 to fixedly connect the installation lugs on the same side of the 2 cantilever beam spring frames 1, the spring frame assembly is fixedly installed on the main reduction support rod

[0045] As Figure 1 and Figure 2 shown, a waist-shaped groove 5 is provided on the upper end surface of each cantilever beam spring frame 1 of the spring frame assembly. At least 1 mass piece 2 is slidably installed on the waist-shaped groove 5 of the cantilever beam spring frame 1 by using the second connecting bolt 3

[0046] In the high-frequency dual-frequency vibration absorber provided by the embodiment of the present utility model, stiffness frequency modulation and mass frequency modulation can be realized. The realization methods are respectively

[0047] On the one hand, the position of the mass piece 2 installed on each cantilever beam spring frame 1 can slide within the waist-shaped groove, which is used to change the overall stiffness of the high-frequency dual-frequency vibration absorber

[0048] On the other hand, by changing the number of mass pieces 2 installed on each cantilever beam spring frame 1, the noise reduction frequency range of the vibration absorber is adjusted

[0049] Based on the dual-frequency modulation method of the high-frequency dual-frequency vibration absorber provided by the embodiment of the present utility model, by selecting the appropriate position of the mass piece 2 and the number of mass pieces 2, high-frequency vibration reduction from the main reduction gear to the fuselage can be realized without damaging the structure of the main reduction support rod and meeting the weight requirements, and further control of the high-frequency harmonic noise generated by the meshing of the helicopter main reduction gears can be realized

[0050] In one implementation manner of the embodiment of the present utility model, the diameter of the arc groove 9 of each cantilever beam spring frame 1 of the spring frame assembly is the same as the diameter of the main reduction support rod, and the circumference of the arc groove 9 is less than half of the circumference of the main reduction support rod

[0051] In this implementation, based on the size setting of the arc groove 9, it can be ensured that after the two cantilever beam spring frames 1 are relatively installed on the main strut, a certain gap is left between the two cantilever beam spring frames 1 for fastening.

[0052] In one implementation of an embodiment of the utility model, in each of the cantilever beam spring frames 1, a waist-shaped groove 5 for slidingly installing the mass piece 2 is arranged along the symmetry axis direction of the cantilever beam spring frame 1, and the shortest distance between the end of the waist-shaped groove 5 close to one side of the main support rod and the arc groove 9 of the cantilever beam spring frame 1 is greater than the radius of the mass piece 2.

[0053] In this implementation, based on the setting of the size of the waist-shaped groove 5, it can be ensured that the mass piece 2 does not contact the main bracing rod when sliding to the innermost side.

[0054] In one implementation of the present invention, in order to reduce the weight of the vibration absorber while meeting the structural rigidity, three square holes 6 of the same size can be opened on the side wall of the cantilever beam spring frame 1 to penetrate the side wall of the cantilever beam spring frame 1 .

[0055] Optionally, all substructures of the high-frequency dual-frequency modulation vibration absorber in the embodiment of the utility model can be made of aviation low-carbon steel 30CrMnSi.

[0056] The embodiment of the utility model provides a high-frequency dual-frequency modulation vibration absorber for helicopter main noise reduction control. In order to improve the structural stiffness while reducing the structural weight as much as possible, a hollow cantilever beam-like structure is selected as the spring frame structure of the high-frequency dual-frequency modulation vibration absorber, that is, the cantilever beam spring frame 1, and a waist-shaped groove is opened in the middle of the spring frame 1 so that the mass sheet 2 can be slidably installed; the high-frequency dual-frequency modulation vibration absorber provided by the embodiment of the utility model can achieve two aspects of frequency modulation: on the one hand, the overall stiffness of the structure is changed by sliding the position of the mass sheet 2 in the waist-shaped groove 5; on the other hand, the noise reduction frequency range of the vibration absorber can be adjusted by changing the number of mass sheets 2. Therefore, by adopting the high-frequency dual-frequency modulation vibration absorber provided by the embodiment of the utility model, by selecting the appropriate position of the mass sheet 2 and the number of mass sheets 2, high-frequency vibration reduction from the main reducer to the fuselage can be achieved without destroying the strut structure and meeting the weight requirements, thereby achieving high-frequency harmonic noise control generated by the meshing of the helicopter main reducer gears. The high-frequency dual-frequency modulation vibration absorber provided by the embodiment of the utility model has the following beneficial effects:

[0057] First, the main structure can be processed in one piece without splicing, effectively avoiding problems such as easy decomposition of interfaces caused by multiple materials, complex structures and difficult processing, and it is easy to install without damaging the structure of the main struts;

[0058] Second, the cantilever beam spring frame 1 designed in the embodiment of the utility model has a large thickness, which effectively improves the structural rigidity, thereby achieving high-frequency noise reduction;

[0059] Thirdly, the high-frequency dual-frequency vibration absorber provided by the embodiment of the present invention has two frequency modulation methods, namely stiffness frequency modulation and mass frequency modulation, and the frequency modulation is convenient and easy to achieve.

[0060] The vibration reduction effect of the high-frequency dual-frequency vibration absorber for helicopter main reduction noise control provided by the present invention is described below through some specific embodiments. Specific Embodiment

[0062] Referring to Figures 1 to 3 As shown in the figure, the main structure of the high-frequency dual-frequency vibration absorber for helicopter main reduction noise control provided by the embodiment of the present invention includes: a spring frame assembly and a mass plate 2.

[0063] The spring frame assembly includes: 2 cantilever beam spring frames 1 symmetrically installed. An arc groove 9 with the same aperture is opened on the installation end face of each cantilever beam spring frame 1, and installation lugs are provided on both sides of the opposite installation end faces. Spring frame installation holes 7 are provided on the installation lugs. By wrapping the 2 cantilever beam spring frames 1 in a form with the installation end faces facing each other around the main reduction support rod, and using the first connecting bolt 4 to pass through the spring frame installation holes 7 of the same-side installation lugs of the 2 cantilever beam spring frames 1 and fixedly connecting the 2 cantilever beam spring frames 1, the spring frame assembly is fixedly installed on the main reduction support rod.

[0064] A waist-shaped groove 5 is opened on the upper end face of each cantilever beam spring frame 1 of the spring frame assembly. A mass plate installation hole 8 is provided on each mass plate 2. The second connecting bolt 3 is used to pass through the mass plate installation hole 8 and the waist-shaped groove 5 to slidably install at least 1 mass plate 2 on the waist-shaped groove 5 of the cantilever beam spring frame 1.

[0065] To verify the effectiveness of the high-frequency dual-frequency vibration absorber for helicopter main reduction noise control provided by the embodiment of the present invention, simulations and tests were respectively carried out. Tests were carried out on the main reduction platform of a certain type of aircraft, and the hammer impact method was used for testing. It should be noted that the high-frequency dual-frequency vibration absorber provided by the embodiment of the present invention has two installation directions. Figure 4 This is a schematic diagram of the installation form of the high-frequency dual-frequency vibration absorber for helicopter main reduction noise control provided by the embodiment of the present invention on the main reduction support rod; as Figure 4 shown in Figures a and b, Figure a is installed along the x direction of the main reduction support rod, and Figure b is installed along the y direction of the main reduction support rod.

[0066] Vibration Absorber State 1:

[0067] Figure 5 This is an installation schematic diagram of the vibration absorber state 1 of the high-frequency dual-frequency vibration absorber provided by the embodiment of the present invention. As Figure 5As shown, one mass piece 2 is attached to the end of the cantilever beam spring frame 1 of the high-frequency dual-frequency vibration absorber. The vibration absorber is installed in the middle position of the support rod along the y direction. The axial vibration absorption effect of the main reduction support rod is as Figure 6 shown, Figure 6 For Figure 5 the schematic diagram of the vibration absorption effect of the high-frequency dual-frequency vibration absorber in the absorber state 1 at the simulated vibration absorption frequency point and the test vibration absorption frequency point.

[0068] Figure 6 Figure a shows the vibration absorption effect of the high-frequency dual-frequency vibration absorber at the simulated vibration absorption frequency point of 1162 Hz in the absorber state 1, and Figure b shows the vibration absorption effect of the high-frequency dual-frequency vibration absorber at the test vibration absorption frequency point of 1107 Hz in the absorber state 1.

[0069] Absorber state 2:

[0070] Figure 7 This is the installation schematic diagram of the absorber state 2 of the high-frequency dual-frequency vibration absorber provided by the embodiment of the present invention. As Figure 7 shown, five mass pieces 2 are attached to the end of the cantilever beam spring frame 1 of the high-frequency dual-frequency vibration absorber. The vibration absorber is installed in the middle position of the support rod along the y direction. The axial vibration absorption effect of the main reduction support rod is as Figure 7 shown, Figure 8 For Figure 7 the schematic diagram of the vibration absorption effect of the high-frequency dual-frequency vibration absorber at the simulated vibration absorption frequency point and the test vibration absorption frequency point in the absorber state 2.

[0071] Figure 8 Figure a shows the vibration absorption effect of the high-frequency dual-frequency vibration absorber at the simulated vibration absorption frequency point of 937 Hz in the absorber state 2, and Figure b shows the vibration absorption effect of the high-frequency dual-frequency vibration absorber at the test vibration absorption frequency point of 950 Hz in the absorber state 2.

[0072] Absorber state 3:

[0073] Figure 9 This is the installation schematic diagram of the absorber state 3 of the high-frequency dual-frequency vibration absorber provided by the embodiment of the present invention. As Figure 9 shown, five mass pieces 2 are attached to the inner end of the cantilever beam spring frame 1 of the high-frequency dual-frequency vibration absorber. The vibration absorber is installed in the middle position of the support rod along the y direction. The axial vibration absorption effect of the main reduction support rod is as Figure 10 shown, Figure 10 For Figure 9 the schematic diagram of the vibration absorption effect of the high-frequency dual-frequency vibration absorber at the simulated vibration absorption frequency point of 1090 Hz in the absorber state 3.

[0074] Absorber state 4:

[0075] Figure 11This is the installation schematic diagram of the absorber state 4 of the high-frequency dual-frequency vibration absorber provided by the embodiment of the present utility model. As Figure 11 shown, 5 mass plates 2 are attached to the end of the cantilever beam spring frame 1 of the high-frequency dual-frequency vibration absorber, and the vibration absorber is installed in the middle position of the strut along the x direction. The vibration absorption effect of the main reduction strut in the x direction is as Figure 12 shown. Figure 12 For Figure 11 shown is the schematic diagram of the vibration absorption effect of the high-frequency dual-frequency vibration absorber in absorber state 4 - vibration absorption frequency point 1441 Hz.

[0076] Absorber state 5:

[0077] Referring to Figure 7 the installation form shown, it can also be used as the installation form of absorber state 5. 5 mass plates 2 are attached to the end of the cantilever beam spring frame 1 of the high-frequency dual-frequency vibration absorber, and the vibration absorber is installed in the middle position of the strut along the y direction. The vibration absorption effect of the main reduction strut in the y direction is as Figure 13 shown. Figure 13 For Figure 7 shown is the schematic diagram of the vibration absorption effect of the high-frequency dual-frequency vibration absorber in absorber state 5 - vibration absorption frequency point 937 Hz.

[0078] Through the above simulation calculations and experimental tests, it is verified that the high-frequency dual-frequency vibration absorber provided by the present utility model has stiffness frequency modulation, mass frequency modulation and multi-directional vibration absorption, and the vibration absorption frequency point can reach more than 1000 Hz, and the vibration absorption bandwidth is greater than 200 Hz, which can effectively reduce the structural vibration transmitted from the main reduction to the bottom of the strut, thereby reducing the structural sound transmitted from the main reduction to the airframe.

[0079] Although the disclosed embodiments of the present utility model are as above, the content is only the embodiments adopted for facilitating the understanding of the present utility model, and is not used to limit the present utility model. Any person skilled in the art within the scope of the present utility model can make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed by the present utility model. However, the scope of patent protection of the present utility model shall still be subject to the scope defined by the appended claims.

Claims

1. A high-frequency dual-frequency vibration absorber for helicopter main reduction noise control, characterized in that, Comprising: A spring frame assembly and a mass sheet (2); Wherein, the spring frame assembly includes: two symmetrically installed cantilever beam spring frames (1). On the installation end face of each cantilever beam spring frame (1), there are arc grooves (9) with the same aperture. And on both sides of the relatively arranged installation end faces, there are installation lugs. By arranging the two cantilever beam spring frames (1) with their installation end faces facing each other around the main reduction strut, and using the first connecting bolts (4) to fixedly connect the installation lugs on the same side of the two cantilever beam spring frames (1), the spring frame assembly is fixedly installed on the main reduction strut; On the upper end face of each cantilever beam spring frame (1) of the spring frame assembly, there is a waist-shaped groove (5). At least one mass sheet (2) is slidably installed on the waist-shaped groove (5) of the cantilever beam spring frame (1) by using the second connecting bolts (3).

2. The high-frequency dual-frequency vibration absorber for helicopter main reduction noise control according to claim 1, characterized in that The position of the mass sheet (2) installed on each cantilever beam spring frame (1) slides within the waist-shaped groove, for changing the overall stiffness of the high-frequency dual-frequency vibration absorber.

3. The high-frequency dual-frequency vibration absorber for helicopter main reduction noise control according to claim 1, characterized in that By changing the number of the mass sheets (2) installed on each cantilever beam spring frame (1), the noise reduction frequency range of the vibration absorber is adjusted.

4. The high-frequency dual-frequency vibration absorber for helicopter main reduction noise control according to any one of claims 1 to 3, characterized in that The diameter of the arc groove (9) of each cantilever beam spring frame (1) of the spring frame assembly is the same as the diameter of the main reduction strut, and the circumference of the arc groove (9) is less than half of the circumference of the main reduction strut.

5. The high-frequency dual-frequency vibration absorber for helicopter main reduction noise control according to any one of claims 1 to 3, characterized in that In each cantilever beam spring frame (1), the waist-shaped groove (5) for slidably installing the mass sheet (2) is arranged along the symmetry axis direction of this cantilever beam spring frame (1), and the shortest distance between the end of the waist-shaped groove (5) close to the main reduction strut and the arc groove (9) of this cantilever beam spring frame (1) is greater than the radius of the mass sheet (2).

6. The high-frequency dual-frequency vibration absorber for helicopter main reduction noise control according to any one of claims 1 to 3, characterized in that On the side wall of each cantilever beam spring frame (1), there are a plurality of square holes with the same size, penetrating the side wall of the cantilever beam spring frame (1).

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