Vibration reduction clamp for helicopter externally-hung supporting rod

Abstract

The utility model belongs to the field of helicopter external hanging structure design, and particularly relates to a vibration reduction clamp for a helicopter external hanging supporting rod. Local vibration reduction treatment of the added large externally-hung supporting rod is improper, so that the vibration level of key parts on a machine is easily increased, and the function completeness of added structural equipment is influenced. The device comprises a front clamp assembly and a rear clamp assembly which are fixed below a helicopter body, an upper clamping structure is connected with the helicopter body, the helicopter externally-hung supporting rod is fixed in a molded surface of a lower clamping structure in advance, and the upper clamping structure and the lower clamping structure are provided with mounting surfaces which are in butt joint. After the upper clamping structure and the lower clamping structure are connected, a molded surface for containing the helicopter externally-hung supporting rod is formed, and the high-damping-ratio rubber pad is installed in the molded surface. The cantilever beam structure is simple in structure and reliable in strength, the length of a free force arm of the cantilever beam structure is changed by adjusting the positions of the front and rear hoops on the supporting rod, and therefore the inherent frequency attribute of the cantilever beam structure is changed. And good energy dissipation performance is achieved, and the vibration level is reduced.

Description

Technical Field

[0001] The utility model belongs to the field of helicopter external suspension structure design, and particularly relates to a vibration damping clamp for a helicopter external suspension strut. Background Art

[0002] Due to its unique advantages such as vertical takeoff and landing, helicopters have been widely used in fields such as search and rescue, sensing and detection. However, the single-rotor with tail-rotor structure form causes all components on the aircraft to be in a harsh vibration environment all the time, accelerating the fatigue damage process of the components on the aircraft, affecting the driving comfort of the pilot, and even affecting flight safety.

[0003] To meet the diverse needs of customers, helicopters need to be continuously improved and modified. The large external suspension strut installed to achieve the detection function will change the local dynamic characteristics of the front fuselage and the vibration attributes of the cockpit structure. At the same time, for helicopters that have been designed and finalized and mass-produced, the main load-bearing structures of their fuselages have been fixed, and there are few optional fixed installation points for the modified structure of the large external suspension strut with high requirements for strength and stiffness. At the same time, the natural frequency of the external suspension strut itself needs to be adjusted to avoid resonance with the rotor excitation frequency and affect the vibration level of the original aircraft.

[0004] Therefore, if the local vibration damping treatment of the large external suspension strut is not properly handled, it is very easy to increase the vibration level of key parts on the aircraft, affect the operation comfort of the pilot, and at the same time affect the functional integrity of the installed structural equipment. Content of the Utility Model

[0005] The purpose of the utility model is to design a locally passive vibration damping clamp with a simple structure, reliable installation and adjustable stiffness, which can not only meet the strict requirements of the installation strength, stiffness and anti-fatigue performance of the large external suspension strut of the helicopter, but also prevent the vibration of the strut itself from affecting the vibration level of the helicopter and the functional integrity of the installed equipment.

[0006] The utility model provides a vibration damping clamp for a helicopter external suspension strut, which includes a front clamp assembly and a rear clamp assembly fixed under the fuselage. Both assemblies include high-damping-ratio rubber pads, lower clamping structures and upper clamping structures. The upper clamping structure is connected to the fuselage. The helicopter external suspension strut is pre-fixed in the profile of the lower clamping structure. The upper clamping structure and the lower clamping structure have butt-jointed mounting surfaces. After the upper clamping structure and the lower clamping structure are connected, they have a profile for accommodating the helicopter external suspension strut, and the high-damping-ratio rubber pad is installed in the profile.

[0007] Advantageously, the lower clamping structure and the upper clamping structure are made of metal materials.

[0008] Advantageously, the upper clamping structure has a "king" - shaped cross-section reinforcing rib.

[0009] Advantageously, the profile for accommodating the external suspension strut of the helicopter is circular.

[0010] Advantageously, the metal material is 2A12 T351 or GJB1741.

[0011] Advantageously, the lower clamping structure and the upper clamping structure are connected by a connecting component on the butt joint mounting surface.

[0012] Advantageously, the upper clamping structure is connected to the airframe by bolts.

[0013] Advantageously, the external suspension strut of the helicopter is pre-riveted and fixed within the profile of the lower clamping structure.

[0014] The damping clamp of the present utility model has the following advantages: First, the structure is simple and the strength is reliable. The "king" - shaped cross - section reinforcing rib is designed to endow the structure with good anti - fatigue performance; Second, the layout position on the strut is flexible and can be arranged arbitrarily at the main bearing structure positions on the airframe that meet the requirements of installation strength and stiffness. By adjusting the positions of the front and rear clamps on the strut, the free - force - arm length of the cantilever beam structure can be changed, so as to change its own natural frequency attribute and avoid resonance with the rotor excitation frequency; Finally, the inner lining of the clamp has a high - damping rubber pad, which has good energy dissipation performance and can effectively reduce the vibration energy transfer between the strut and the airframe, further reducing the vibration level. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is the installation drawing of the damping clamp of the present utility model;

[0016] Figure 2 is the structural sectional view of the damping clamp of the present utility model;

[0017] Figure 3 is the "king" - shaped cross - section reinforcing rib of the damping clamp of the present utility model.

[0018] 1 - front clamp assembly, 2 - rear clamp assembly, 3 - connecting component, 4 - high - damping - ratio rubber pad, 5 - lower clamping structure, 6 - upper clamping structure DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] The present utility model is a damping clamp for the external suspension strut of a helicopter, which includes a front clamp assembly 1 and a rear clamp assembly 2. Among them, both the front clamp assembly 1 and the rear clamp assembly 2 are designed with a metal material 2A12 T351 / GJB1741 and a machining structure form, and are connected to the airframe by bolts; the front clamp assembly 1 and the rear clamp assembly 2 are used to clamp and fix the strut structure and provide connection with the airframe, and are each composed of an upper clamping structure 6, a lower clamping structure 5, a connecting component 3 and a high - damping - ratio rubber pad 4.

[0020] The front clamp assembly 1 and the rear clamp assembly 2 are arranged flexibly on the support rod. The specific positions can be designed according to the frequency modulation design and the installation positions available on the airframe, so as to adjust the free force arm length of the cantilever beam structure of the support rod, realize the frequency adjustment of the support rod itself, avoid resonance with the rotor passing frequency, and avoid excessive local vibration level, which may affect the structural safety and ride comfort.

[0021] The upper clamping structure 6 has a "king" - shaped cross - section reinforcing rib designed by topology optimization technology, which meets the requirements of static strength and stiffness, and has excellent anti - fatigue characteristics. The specially designed cross - section structure also maintains the optimal structural weight. The lower clamping structure 5 and the upper clamping structure 6 are combined and fixed to clamp and fix the support rod.

[0022] Inside the upper clamping structure 6 and the lower clamping structure 5, a rubber pad 4 with a high damping ratio is designed, which can efficiently dissipate the vibration energy of the support rod itself, and further weaken the mutual influence of the vibration characteristics between the support rod and the airframe caused by rigid connection.

[0023] The upper clamping structure 6 and the lower clamping structure 5 are made of metal materials, and the support rod is made of composite materials. The designed rubber pad 4 with a high damping ratio can also prevent the harmful wear between the structures of two different materials.

[0024] When the specific implementation of the present utility model is carried out, first, according to the installation point positions on the airframe that can meet the installation strength and stiffness requirements of the external - hanging support rod and combined with the results of finite - element dynamic simulation analysis, determine the arrangement positions of the front and rear two components of the vibration - damping clamp on the support rod; then connect the upper clamping structure 6 with the local airframe structure, rivet the lower clamping structure 5 with the support rod, and finally use the connecting component 3 to bolt - connect and fix the upper and lower clamping structures. At the same time, ensure that the rubber pad 4 with a high damping ratio is closely attached to the support rod. After installation, the method of external ground excitation can be used to measure whether the natural vibration frequency of the external - hanging support rod避开 the rotor excitation frequency, and then conduct actual flight vibration measurement to verify the vibration - damping effect of the present utility model.

[0025] Embodiment

[0026] The vibration - damping clamp manufactured according to the technical solution of the present utility model patent has passed the verification of installation and flight test. Through visual inspection, the installation and fixation of the external - hanging support rod are firm and no fatigue damage cracks are found. At the same time, the flight vibration measurement results show that the Z - direction vibration value of the cockpit floor is 0.16g, the Z - direction vibration value of the crew seat floor is 0.14g, and the Z - direction vibration value of the instrument panel is 0.12g, and the pilot feels comfortable. It is proved that this vibration - damping device can effectively weaken the influence of the self - vibration of the external - hanging support rod on the vibration level of the airframe, and has a good vibration - damping effect, and will not affect the ride comfort and flight safety.

Claims

1. A vibration damping clamp for a helicopter external strut, characterized in that: The front clamp assembly (1) and the rear clamp assembly (2) fixed under the airframe both include a high damping ratio rubber pad (4), a lower clamping structure (5) and an upper clamping structure (6). Among them, the upper clamping structure (6) is connected to the airframe. The helicopter external hanging strut is pre-fixed in the profile of the lower clamping structure (5). The upper clamping structure (6) and the lower clamping structure (5) have a butt joint mounting surface. After the upper clamping structure (6) and the lower clamping structure (5) are connected, they have a profile for accommodating the helicopter external hanging strut, and the high damping ratio rubber pad (4) is installed in the profile.

2. The vibration damping clamp for helicopter external struts according to claim 1, characterized in that: The lower clamping structure (5) and the upper clamping structure (6) are made of metal materials.

3. The vibration damping clamp for helicopter external struts according to claim 1, characterized in that: The upper clamping structure (6) has a "king" shaped cross-section reinforcing rib.

4. The vibration damping clamp for helicopter external struts according to claim 1, characterized in that: The profile for accommodating the helicopter external hanging strut is circular.

5. The vibration damping clamp for helicopter external struts according to claim 2, characterized in that: The metal material is 2A12 T351 or GJB1741.

6. The vibration damping clamp for helicopter external struts according to claim 1, characterized in that: The lower clamping structure (5) and the upper clamping structure (6) are connected through a connecting component (3) on the butt joint mounting surface.

7. The vibration damping clamp for helicopter external struts according to claim 1, characterized in that: The upper clamping structure (6) is connected to the airframe by bolts.

8. The vibration damping clamp for helicopter external struts according to claim 1, characterized in that: The helicopter external hanging strut is pre-riveted and fixed in the profile of the lower clamping structure (5).

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