Frequency-adjustable liquid spring damper and frequency adjustment method thereof

Abstract

The application provides a frequency-adjustable liquid-elastic vibration isolator and a frequency adjusting method thereof, and relates to the technical field of liquid-elastic vibration isolators.The liquid-elastic vibration isolator comprises an upper outer cylinder assembly, an inner cylinder assembly, a lower outer cylinder assembly and elastic rubber.The inner wall of the upper outer cylinder assembly and the inner side of the lower outer cylinder assembly are fixedly connected with the outer side of the inner cylinder assembly through the elastic rubber.The inner cylinder assembly comprises an inner cylinder body, a flexible adjusting structure located in the inner cylinder body and a control adjusting mechanism.A liquid channel is arranged in the flexible adjusting structure.The control adjusting mechanism is used for adjusting the diameter of the flexible adjusting structure and the cross-sectional diameter of the liquid channel.The upper liquid cavity and the lower liquid cavity are arranged in the upper outer cylinder assembly and the lower outer cylinder assembly respectively.The upper liquid cavity and the lower liquid cavity are in communication with the liquid channel.The inertia mass and the amplification ratio of the liquid-elastic vibration isolator are adjusted to adjust the vibration isolation frequency of the liquid-elastic vibration isolator, so that the liquid-elastic vibration isolator can adapt to the change of the flight state of a helicopter.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of liquid elastomeric vibration isolator, in particular to a liquid elastomeric vibration isolator with adjustable frequency and a frequency adjusting method thereof. BACKGROUND

[0002] The unique structure of the helicopter determines that the aircraft has the characteristics of high mobility and high flexibility, which makes it play a wide role in the military field and the civil field. The development of the helicopter is highly dependent on the vibration control device. Without effective control of the vibration level of the helicopter body, a good helicopter cannot be developed, and the development of the helicopter will be limited. The main reduction vibration is a commonly used technical means in the vibration control of the helicopter.

[0003] (1) Development of high-speed helicopters

[0004] With the development needs of new rotorcrafts for greater forward flight speed, higher efficiency and longer range, new types of high-speed machines such as tilt-rotor, compound and stop-rotor have appeared. However, due to the influence of flight state and machine structure, new helicopters are prone to greater vibration problems, which will have a serious impact on the pilots and equipment. Therefore, the vibration reduction technology of high-speed helicopters brings new challenges to the vibration control of helicopters. Compared with conventional helicopters, the rotor vibration load and the body vibration level of the coaxial high-speed helicopter are much higher than those of the conventional helicopter in the high-speed and high-mobility flight state. In order to avoid the shock stall of the forward rotor blade at high-speed forward flight, the rotor speed needs to be reduced, which will inevitably change the frequency of the vibration load and thus the frequency of the body vibration response. Taking the American SB-1 "fearless" helicopter as an example, its rotor speed is 7.43 Hz in the hovering state; and its rotor speed is reduced to 6 Hz in the high-speed forward flight state. For the tilt rotor, its rotor speed is 6.6 Hz in the hovering state; and its rotor speed is reduced to 5.5 Hz in the high-speed forward flight state. It can be seen that the main excitation frequency of the high-speed helicopter has two frequency values (N is the number of blades). And the ordinary helicopter only needs to consider the load from the rotor in the hovering state. This makes it necessary to consider multiple frequencies when designing the vibration isolator of the high-speed helicopter. The above characteristics determine that the design of the vibration isolator of the high-speed helicopter is different from that of the ordinary helicopter, and its operation process involves vibration isolation at two frequency values, while the existing liquid elastomeric vibration isolator of the helicopter can only realize vibration isolation at a single frequency.

[0005] In view of the vibration control problem of the high-speed helicopter under the action of external dynamic load, a liquid elastomeric vibration isolator with adjustable frequency is established to realize vibration isolation in a specified frequency range, which has strong practical significance for improving the technical level of the helicopter vibration reduction in China. SUMMARY

[0006] In view of the problem that the liquid spring vibration isolator of the existing helicopter mentioned in the background art can only achieve vibration isolation at a single frequency, the application provides a liquid spring vibration isolator with adjustable frequency and a frequency adjusting method thereof, which adjusts the vibration isolation frequency of the liquid spring vibration isolator by adjusting the inertia mass and amplification ratio of the liquid spring vibration isolator, so as to adapt to the change of the flight state of the helicopter.

[0007] To achieve the above-mentioned purpose, the application adopts the following technical solutions:

[0008] The application provides a liquid spring vibration isolator with adjustable frequency in a first aspect, which comprises an upper outer cylinder assembly, an inner cylinder assembly, a lower outer cylinder assembly and an elastic rubber.

[0009] The inner cylinder assembly is arranged between the upper outer cylinder assembly and the lower outer cylinder assembly, and the inner wall of the upper outer cylinder assembly and the inner side of the lower outer cylinder assembly are fixedly connected with the outer side of the inner cylinder assembly through the elastic rubber, so that the lower outer cylinder assembly and the upper outer cylinder assembly can axially relatively displace with the inner cylinder assembly.

[0010] The inner cylinder assembly comprises an inner cylinder body, a flexible adjusting structure arranged in the inner cylinder body and a control adjusting mechanism, a liquid channel is arranged in the flexible adjusting structure, and the control adjusting mechanism is used for adjusting the diameter of the flexible adjusting structure and the cross-sectional diameter of the liquid channel.

[0011] The upper outer cylinder assembly and the lower outer cylinder assembly are respectively provided with an upper liquid cavity and a lower liquid cavity, and the upper liquid cavity and the lower liquid cavity are in communication with the liquid channel.

[0012] As a further description of the application, the control adjusting mechanism comprises a hydraulic oil tank and an adjusting valve.

[0013] An additional liquid chamber is arranged in the inner cylinder body, the flexible adjusting structure penetrates in the additional liquid chamber and is fixedly connected with the inner cylinder body at the upper and lower ends, a liquid injection port is arranged on the side wall of the inner cylinder body, the liquid injection port is in communication with the additional liquid chamber, the liquid injection port is connected with the hydraulic oil tank through a conduit, and the adjusting valve is arranged on the conduit.

[0014] As a further description of the application, the upper and lower ends of the inner cylinder body are provided with stepped mounting holes, the longitudinal section of the flexible adjusting structure is in I-shaped structure, the upper and lower protruding parts of the flexible adjusting structure can extend into the stepped mounting holes, a pressing plate is threadedly connected in the stepped mounting hole, the pressing plate is used for sealing and fixing the flexible adjusting structure in the additional liquid chamber, a first communication port with the same diameter as the liquid channel is arranged on the pressing plate and in communication with the liquid channel, and the upper liquid cavity and the lower liquid cavity can be in communication with the liquid channel.

[0015] As a further illustration of the present application, the upper outer cylinder assembly is further provided with a liquid compensation cavity, which is located above the upper liquid cavity, and a second communication port is provided between the liquid compensation cavity and the upper liquid cavity, and the liquid compensation cavity contains a mixture of air and liquid, and when the amount of liquid in the upper liquid cavity is insufficient, the liquid in the liquid compensation cavity can be naturally supplemented into the upper liquid cavity under the action of gravity.

[0016] As a further illustration of the present application, the upper outer cylinder assembly includes an upper outer cylinder end cover, a liquid supplementing plate and an upper outer cylinder which are sequentially fixed and connected from top to bottom.

[0017] The upper end of the upper outer cylinder end cover and the upper and lower ends of the liquid supplementing plate are provided with grooves, so that the liquid compensation cavity is formed between the upper outer cylinder end cover and the liquid supplementing plate, the groove at the lower end of the liquid supplementing plate forms the upper liquid cavity, the second communication port is provided at the center of the liquid supplementing plate, and the inner side of the upper outer cylinder is fixedly connected with the outer side of the elastic rubber.

[0018] As a further illustration of the present application, the lower outer cylinder assembly includes a lower outer cylinder and a lower outer cylinder end cover which are fixedly connected.

[0019] The upper end of the lower outer cylinder end cover is provided with a groove, thereby forming the lower liquid cavity, and the inner side of the lower outer cylinder is fixedly connected with the outer side of the elastic rubber.

[0020] A flange is provided on the outer periphery of the inner cylinder body, long bolts are provided through the upper outer cylinder assembly, the flange and the lower outer cylinder assembly, and the upper outer cylinder assembly and the lower outer cylinder assembly can be fixedly connected through the cooperation of the long bolts and nuts.

[0021] The second aspect of the present application provides a frequency adjustment method of the frequency-adjustable liquid elastomeric vibration isolator, which includes the following processes:

[0022] Determining the target isolation frequency of the frequency-adjustable liquid elastomeric vibration isolator;

[0023] According to the target isolation frequency, the target amplification ratio corresponding to the flexible adjustment structure part of the liquid elastomeric vibration isolator is calculated, and the target amplification ratio is the ratio of the cross-sectional area of the upper liquid cavity or the lower liquid cavity to the cross-sectional area of the liquid passage in the flexible adjustment structure.

[0024] According to the target amplification ratio, the target cross-sectional diameter variation of the liquid passage in the flexible adjustment structure is calculated.

[0025] The flexible adjustment structure is deformed by controlling the adjustment mechanism, so that the internal liquid passage is transformed according to the target cross-sectional diameter variation.

[0026] The third aspect of the present application also provides another frequency adjustment method of the above-mentioned adjustable frequency hydro-elastic vibration isolator, comprising the following processes:

[0027] determining a target isolation frequency of the adjustable frequency hydro-elastic vibration isolator;

[0028] calculating a target amplification ratio corresponding to the flexible adjustment structure part of the hydro-elastic vibration isolator according to the target isolation frequency, the target amplification ratio being a ratio of a cross-sectional area of the upper liquid chamber or the lower liquid chamber to a cross-sectional area of the liquid passage inside the flexible adjustment structure;

[0029] calculating a target pressure of the hydraulic oil in the additional liquid chamber according to the target amplification ratio;

[0030] injecting the hydraulic oil in the hydraulic oil tank into the additional liquid chamber by controlling the adjustment valve, so that the pressure of the hydraulic oil in the additional liquid chamber reaches the target pressure.

[0031] As a further illustration of the present application, the relationship between the target amplification ratio and the target pressure of the hydraulic oil in the additional liquid chamber is:

[0032] ;

[0033] wherein, the target amplification ratio; the initial cross-sectional diameter of the liquid passage before deformation, the cross-sectional area of the upper liquid chamber and the lower liquid chamber, the cross-sectional area of the liquid passage; the target pressure of the hydraulic oil, the derivative of the diameter change of the liquid passage and the pressure, which is related to the material properties and is a constant term here.

[0034] Compared with the prior art, the present application has the following beneficial technical effects:

[0035] The present application provides a design scheme of an adjustable frequency hydro-elastic vibration isolator, which adjusts the isolation frequency of the hydro-elastic vibration isolator by adjusting the amplification ratio of the hydro-elastic vibration isolator, so as to adapt to the change of the flight state of the helicopter.

[0036] Other features and advantages of the present application will be described in the following description, and some will become apparent from the description, or will be understood from the practice of the present application. The purpose and other advantages of the present application can be achieved and obtained by the structure specifically pointed out in the written description and the accompanying drawings.

[0037] The technical solutions of the present application will be further described in detail below with the help of the accompanying drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0038] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, illustrate the present application and explain the technical solutions of the present application, and do not constitute a limitation on the present application.

[0039] Figure 1 A sectional view of the adjustable frequency liquid-elastomer vibration isolator provided by the present application.

[0040] Figure 2 A schematic view of the overall structure of the adjustable frequency liquid-elastomer vibration isolator provided by the present application.

[0041] Figure 3 A schematic view of the inner cylinder assembly of the adjustable frequency liquid-elastomer vibration isolator provided by the present application.

[0042] Figure 4 A schematic view of the force of the adjustable frequency liquid-elastomer vibration isolator provided by the present application.

[0043] Legend of the drawings:

[0044] 1 - upper outer cylinder assembly, 2 - inner cylinder assembly, 3 - lower outer cylinder assembly, 4 - elastic rubber, 5 - adjusting valve, 6 - hydraulic oil tank.

[0045] 101 - long bolt; 102 - upper outer cylinder end cover; 103 - liquid compensation cavity; 104 - liquid supplementing plate; 105 - upper liquid cavity; 106 - upper outer cylinder; 107 - sealing groove;

[0046] 201 - inner cylinder body; 202 - additional liquid chamber; 203 - flexible adjusting structure; 204 - pressing plate; 205 - liquid injection port; 206 - flange; 207 - thread; 208 - liquid passage;

[0047] 301 - lower outer cylinder; 302 - lower outer cylinder end cover; 303 - lower liquid cavity. DETAILED DESCRIPTION

[0048] The preferred embodiments of the present application are described below in conjunction with the accompanying drawings, and it should be understood that the preferred embodiments described herein are only used to explain and illustrate the present application, and do not constitute a limitation on the present application.

[0049] The design principle of the existing liquid elastomer vibration isolator is based on dynamic anti-resonance mechanism, and the vibration isolation effect of the dynamic anti-resonance vibration isolator is very sensitive to frequency, and generally only near the specific anti-resonance frequency point can play a good vibration isolation effect, and deviating from this frequency, the vibration isolation performance will decrease sharply. In actual application, the change of the flight state of the helicopter will cause the change of the rotor frequency, and then the change of the excitation frequency, and once the change of the excitation frequency exceeds the effective frequency range of the vibration isolator, it is difficult to provide effective vibration isolation, resulting in poor vibration isolation effect. The present application aims at the above problems, and proposes a design of a frequency-adjustable liquid elastomer vibration isolator, which adjusts the vibration isolation frequency of the liquid elastomer vibration isolator by adjusting the inertia mass and amplification ratio of the liquid elastomer vibration isolator, so as to adapt to the change of the flight state of the helicopter.

[0050] The present application proposes a design of a frequency-adjustable liquid elastomer vibration isolator, and the core is to adjust the vibration isolation frequency by adjusting the diameter of the inertia channel. Since the diameter of the inertia channel of the liquid elastomer vibration isolator is usually not designed to be very large, even a slight diameter adjustment can significantly change the vibration isolation frequency, thereby achieving obvious adjustment effect.

[0051] Specifically, as shown in Figures 1-3 The present application first provides a frequency-adjustable liquid elastomer vibration isolator, which comprises an upper outer cylinder assembly 1, an inner cylinder assembly 2, a lower outer cylinder assembly 3 and an elastic rubber 4. The inner cylinder assembly 2 is arranged between the upper outer cylinder assembly 1 and the lower outer cylinder assembly 3, and the inner wall of the upper outer cylinder assembly 1 and the inner side of the lower outer cylinder assembly 3 are fixedly connected with the outer side of the inner cylinder assembly 2 through the elastic rubber 4, so that the lower outer cylinder assembly 3 and the upper outer cylinder assembly 1 can axially relatively displace with the inner cylinder assembly 2. The inner cylinder assembly 2 comprises an inner cylinder body 201, a flexible adjusting structure 203 arranged in the inner cylinder body 201, and a control adjusting mechanism. The flexible adjusting structure 203 is provided with a liquid channel 208, and the control adjusting mechanism is used for adjusting the diameter of the flexible adjusting structure 203, and then adjusting the cross-sectional diameter of the liquid channel 208. The upper outer cylinder assembly 1 and the lower outer cylinder assembly 3 are respectively provided with an upper liquid cavity 105 and a lower liquid cavity 303, and the upper liquid cavity 105 and the lower liquid cavity 303 are in communication with the liquid channel 208.

[0052] The vibration isolator designed by the present application is provided with a flexible adjusting structure and a control adjusting mechanism in the inner cylinder, the deformation of the flexible adjusting structure is adjusted, the inertia mass and the amplification ratio inside the vibration isolator are changed, and the vibration isolator can adapt to the change of the excitation frequency, thereby achieving the purpose of widening the vibration isolation frequency band of the liquid elastomer vibration isolator.

[0053] In an implementable mode, the control adjusting mechanism comprises the hydraulic oil tank 6 and the adjusting valve 5; the inner cylinder body 201 is provided with an additional liquid chamber 202, a flexible adjusting structure 203 is arranged in the additional liquid chamber 202, and the upper and lower ends of the flexible adjusting structure 203 are fixedly connected with the inner cylinder body 201; the side wall of the inner cylinder body 201 is provided with a liquid injection port 205, the liquid injection port 205 is in communication with the additional liquid chamber 202, and the liquid injection port 205 is connected with the hydraulic oil tank 6 through a pipeline; and the adjusting valve 5 is arranged on the pipeline.

[0054] The additional liquid chamber is further arranged in the inner cylinder, the flexible adjusting structure is used to seal the additional liquid chamber, the volume of the hydraulic oil in the additional liquid chamber is changed, the pressure of the hydraulic oil in the additional liquid chamber is changed, the flexible adjusting structure is deformed, the inertial mass and the amplification ratio in the vibration isolator are changed, the vibration isolator can adapt to the change of the excitation frequency, and the purpose of widening the vibration isolation frequency band of the liquid spring vibration isolator is achieved.

[0055] In an implementable mode, the inner cylinder body 201 is provided with step mounting holes at the upper and lower ends, the longitudinal section of the flexible adjusting structure 203 is in I-shaped structure, the upper and lower protruding parts of the flexible adjusting structure 203 can extend into the step mounting holes, and the step mounting holes are connected with the pressing plate 204 through threads 207, so that the pressing plate 204 can be firmly connected with the inner cylinder body 201. The pressing plate 204 is used to seal and fix the flexible adjusting structure 203 in the additional liquid chamber 202. During the cooperation and installation of the pressing plate 204 and the inner cylinder body 201, the flexible adjusting structure 203 located between them is fixed in the inner cylinder body 201 under the action of the pressing plate 204. The pressing plate 204 is also provided with a first communication port which is in communication with the liquid channel 208 and has the same diameter, so that the upper liquid cavity 105 and the lower liquid cavity 303 can be in communication with the liquid channel 208. The first communication port and the liquid channel 208 jointly form an inertial channel of the liquid spring vibration isolator. The first communication port is a non-variable part of the diameter of the inertial channel, and the liquid channel 208 is a variable part of the diameter of the inertial channel.

[0056] In an implementable mode, the upper outer cylinder assembly 1 is also provided with a liquid compensation cavity 103, the liquid compensation cavity 103 is located above the upper liquid cavity 105, and a second communication port is arranged between the liquid compensation cavity 103 and the upper liquid cavity 105. The liquid compensation cavity 103 contains a mixture of air and liquid. When the amount of liquid in the upper liquid cavity 105 is insufficient, the liquid in the liquid compensation cavity 103 can be naturally supplemented into the upper liquid cavity 105 under the action of gravity, so as to ensure that the vibration isolator can continuously and stably operate. A part of space is reserved in the liquid compensation cavity 103 for containing air. When the flexible adjusting structure 203 is deformed due to the action of the hydraulic oil, the excess liquid in the inertial channel can be safely stored in the space reserved in the liquid compensation cavity 103.

[0057] In an implementable mode, the upper outer cylinder assembly 1 comprises an upper outer cylinder end cover 102, a liquid compensation plate 104 and an upper outer cylinder 106 fixedly connected in sequence from top to bottom; the upper end of the upper outer cylinder end cover 102 and the upper and lower ends of the liquid compensation plate 104 are provided with grooves, so that a liquid compensation cavity 103 is formed between the upper outer cylinder end cover 102 and the liquid compensation plate 104, the groove at the lower end of the liquid compensation plate 104 forms an upper liquid cavity 105, and a second communication port is arranged at the center position of the liquid compensation plate 104; the inner side surface of the upper outer cylinder 106 is fixedly connected with the outer side surface of the elastic rubber 4.

[0058] Further, bolt holes are reserved at corresponding positions of the upper outer cylinder end cover 102, the liquid compensation plate 104 and the upper outer cylinder 106, so that the long bolt 101 can pass through smoothly; the long bolt 101 passes through the bolt holes pre-formed at the edges of the upper outer cylinder end cover 102, the liquid compensation plate 104 and the upper outer cylinder 106 in sequence, and the three components are fixed together through cooperation with a nut.

[0059] The upper outer cylinder end cover 102 and the liquid compensation plate 104 are closely combined and jointly construct a closed liquid compensation cavity 103 located in the upper region of the liquid compensation plate 104. In order to ensure the sealing property of the liquid cavity, a sealing groove 107 is further designed on the liquid compensation plate 104, and through installation of a sealing ring in the sealing groove 107, liquid leakage can be effectively prevented, and normal work of the liquid spring vibration isolator can be ensured.

[0060] In an implementable mode, the lower outer cylinder assembly 3 comprises a lower outer cylinder 301 and a lower outer cylinder end cover 302 fixedly connected; the upper end of the lower outer cylinder end cover 302 is provided with a groove, so as to form a lower liquid cavity 303; the inner side surface of the lower outer cylinder 301 is fixedly connected with the outer side surface of the elastic rubber 4. Specifically, bolt holes are reserved at corresponding positions of the lower outer cylinder 301 and the lower outer cylinder end cover 302, so that the long bolt 101 can pass through, and the lower outer cylinder 301 and the lower outer cylinder end cover 302 are fixed together through the long bolt 101 and a nut.

[0061] Specifically, the two elastic rubbers 4 are arranged between the lower outer cylinder 301 and the inner cylinder 2 and between the upper outer cylinder 106 and the inner cylinder 2 respectively; the side surfaces of the elastic rubbers 4 are bonded with the upper outer cylinder 106, the lower outer cylinder 301 and the inner cylinder 2 respectively; when vertical relative movement occurs between the outer cylinder and the inner cylinder, the elastic rubbers 4 generate shear deformation and provide elastic stiffness.

[0062] In an implementable mode, a flange 206 is arranged on the outer periphery of the inner cylinder body 201, long bolts 101 are arranged through the flange 206, the upper outer cylinder assembly 1 and the lower outer cylinder assembly 3, and the upper outer cylinder assembly 1 and the lower outer cylinder assembly 3 are fixedly connected through the cooperation of the long bolts 101 and nuts. Specifically, bolt holes are arranged on the flange 206 at corresponding positions so that the long bolts 101 can pass through, and the upper outer cylinder assembly 1 and the lower outer cylinder assembly 3 are fixed together by the long bolts 101, so that the displacement of the two is consistent.

[0063] Specifically, the adjustable frequency vibration isolator is arranged between the main reducer of the helicopter and the fuselage through the flange 206 and the lower outer cylinder assembly 3 of the liquid elastomer vibration isolator, and is used for vibration isolation.

[0064] The second aspect of the present application provides a frequency adjustment method of the adjustable frequency liquid elastomer vibration isolator, comprising the following steps:

[0065] Step 1: determining the target vibration isolation frequency of the adjustable frequency liquid elastomer vibration isolator.

[0066] Step 2: calculating the target amplification ratio corresponding to the flexible adjustment structure part of the liquid elastomer vibration isolator according to the target vibration isolation frequency, and the target amplification ratio is the ratio of the cross-sectional area of the upper liquid chamber or the lower liquid chamber to the cross-sectional area of the liquid passage in the flexible adjustment structure.

[0067] The theoretical model of the present application can be equivalent to Figure 4 In the model, represents the mass of the fuselage and the outer cylinder base, represents the mass of the vibration-isolated part composed of the main reducer and the rotor of the helicopter and the inner cylinder, represents the mass of the liquid in the inertia passage of the diameter-invariable part, represents the mass of the liquid in the inertia passage in contact with the flexible adjustment structure (the diameter of this part is variable). represents the periodic excitation force acting on the inner cylinder of the liquid elastomer vibration isolator, respectively represent the displacement of the outer cylinder and the inner cylinder under the action of the external excitation force, represents the displacement of the inertia mass , and represents the displacement of the inertia mass .

[0068] represents the cross-sectional diameter of the upper and lower liquid chambers of the liquid elastomer vibration isolator, represents the cross-sectional diameter of the inertia passage of the diameter-invariable part, represents the cross-sectional diameter of the inertia passage of the diameter-variable part, represents the stiffness of the rubber, is the total length of the inertia passage, is the length of the diameter variable part. is the cross-sectional area of the upper and lower liquid cavity, is the cross-sectional area of the inertia passage of the diameter variable part, is the cross-sectional area of the inertia passage of the diameter variable part.

[0069] In the theoretical analysis of the liquid spring vibration isolator, the following basic assumptions are made to simplify the model:

[0070] (1) The changes in the physical state of the liquid and rubber in the liquid spring vibration isolator during operation have no effect on the working state;

[0071] (2) The change in the stiffness of the rubber is a linear process;

[0072] (3) The liquid spring vibration isolator always maintains an axial motion state.

[0073] (4) The deformation of each position of the flexible adjustment structure is consistent.

[0074] The amplification ratio of the adjustable frequency liquid spring vibration isolator is defined as the ratio of the cross-sectional areas of the upper and lower liquid cavities and the inertia passage Based on the principle that the change in the volume of the liquid in the upper and lower liquid cavities is exactly equal to the mass of the liquid flowing through the inertia passage, the following two continuous equations can be further derived:

[0075]

[0076] The kinetic energy and potential energy of the system are:

[0077]

[0078] First, the continuous equation is brought into the expression of the kinetic energy and potential energy of the system to eliminate , and then the obtained kinetic energy and potential energy expressions are brought into the Lagrange equation, and according to the frequency response function of the system, the vibration isolation frequency can be obtained as follows:

[0079]

[0080] After determining the target vibration isolation frequency of the adjustable frequency liquid spring vibration isolator, since all the parameters in the above vibration isolation frequency calculation formula are known constants except R1 (the target amplification ratio of the flexible adjustment structure part), the target amplification ratio R1 can be calculated by the above formula.

[0081] Step 3: Calculate the target cross-sectional diameter change of the liquid passage inside the flexible adjustment structure according to the target amplification ratio.

[0082] Step 4: Control the deformation of the flexible adjustment structure by controlling the adjustment mechanism, so that the internal liquid channel changes according to the target cross-sectional diameter change.

[0083] Since the target magnification ratio R1 is the ratio of the cross-sectional area of ​​the upper or lower liquid cavity to the cross-sectional area of ​​the liquid channel inside the flexible adjustment structure, when the cross-sectional area of ​​the upper or lower liquid cavity is known, the target cross-sectional diameter change of the liquid channel inside the flexible adjustment structure can be calculated based on the target magnification ratio. Finally, by controlling the adjustment mechanism to deform the flexible adjustment structure, the internal liquid channel is changed according to the target cross-sectional diameter change, thereby adjusting the vibration isolation frequency of the vibration isolator to the target vibration isolation frequency.

[0084] Preferably, after step 2 above, steps 3-4 can be replaced with the following specific steps 5-6, thereby realizing the specific adjustment process of the vibration isolation frequency of the vibration isolator.

[0085] Step 5: Calculate the target pressure of the hydraulic oil in the auxiliary fluid chamber based on the target magnification ratio.

[0086] Specifically, the relationship between the target magnification ratio and the target pressure of the hydraulic oil in the auxiliary fluid chamber is as follows:

[0087] ;

[0088] in, Target magnification ratio; The initial cross-sectional diameter of the liquid channel before deformation. Let be the cross-sectional area of ​​the upper and lower liquid cavities. This represents the cross-sectional area of ​​the liquid channel; The target pressure of the hydraulic oil. This is the derivative of the change in diameter of the liquid channel with respect to the pressure, which is related to the material properties and is a constant term here.

[0089] Step 6: By controlling the regulating valve, the hydraulic oil in the hydraulic oil tank is injected into the auxiliary fluid chamber, so that the pressure of the hydraulic oil in the auxiliary fluid chamber reaches the target pressure.

[0090] Figure 1 202 is an auxiliary liquid chamber, connected to the hydraulic oil tank 6 via regulating valve 5. When the valve is closed, the flexible regulating structure does not deform, and the amplification ratio with the vibration isolator is [not specified]. for:

[0091]

[0092] When the valve opens, the flexible adjustment structure deforms under the action of hydraulic oil, thus affecting the cross-sectional area of ​​the corresponding channel. Therefore, the amplification ratio of the vibration isolator is affected. Changeable: Based on the above relationship between the target amplification ratio and the target pressure of the hydraulic oil in the additional liquid chamber, the combined liquid spring vibration isolator can charge and discharge hydraulic oil with different pressures in the additional liquid chamber , and by adjusting the amplification ratio

[0093] In summary, the adjustable frequency liquid spring vibration isolator provided by the present application is designed for vibration reduction of a high-speed helicopter. The flange of the inner cylinder is connected to the main reducer of the helicopter for transmitting the excitation force generated by the vibration of the main reducer. The upper and lower end covers of the outer cylinder are connected to the fuselage.

[0094] The high-speed helicopter has two flight states: hovering and forward flight, which correspond to different excitation frequencies. When the helicopter is in the hovering state, the liquid spring vibration isolator performs vibration isolation according to the dynamic anti-resonance principle: at this time, the liquid in the inertia channel is squeezed and flows up and down in the channel to generate an inertia force, which counteracts the force generated by the elastic element, thereby achieving vibration isolation. At this time, the flexible adjustment structure remains in the undeformed state. When the helicopter changes from the hovering state to the forward flight state, the adjustable frequency liquid spring vibration isolator adjusts the deformation of the flexible adjustment structure by increasing the oil pressure of the hydraulic oil in the additional liquid chamber. The deformation of the flexible adjustment structure will cause the diameter of the inertia channel to change, thereby changing the vibration isolation frequency of the vibration isolator, to ensure that the vibration isolation frequency of the vibration isolator matches the excitation frequency under the current flight state.

[0095] Obviously, those skilled in the art can make various modifications and variations to the present technical solution without departing from the spirit and scope of the present technical solution. Therefore, if these modifications and variations of the present technical solution fall within the scope of the claims of the present technical solution and their equivalent technologies, the present technical solution also intends to include these modifications and variations.

Claims

1. A frequency-adjustable liquid-elastic vibration isolator, characterized in that, include: Upper outer cylinder assembly (1), inner cylinder assembly (2), lower outer cylinder assembly (3) and elastic rubber (4); The inner cylinder assembly (2) is disposed between the upper outer cylinder assembly (1) and the lower outer cylinder assembly (3). The inner wall of the upper outer cylinder assembly (1) and the inner side of the lower outer cylinder assembly (3) are fixedly connected to the outer side of the inner cylinder assembly (2) by elastic rubber (4), so that the lower outer cylinder assembly (3) and the upper outer cylinder assembly (1) can generate axial relative displacement with respect to the inner cylinder assembly (2). The inner cylinder assembly (2) includes an inner cylinder body (201), a flexible adjustment structure (203) located within the inner cylinder body (201), and a control adjustment mechanism. The flexible adjustment structure (203) is provided with a liquid channel (208). The control adjustment mechanism is used to adjust the diameter of the flexible adjustment structure (203), thereby adjusting the cross-sectional diameter of the liquid channel (208). The upper outer cylinder assembly (1) and the lower outer cylinder assembly (3) are respectively provided with an upper liquid chamber (105) and a lower liquid chamber (303), and the upper liquid chamber (105) and the lower liquid chamber (303) are both connected to the liquid channel (208); The control and adjustment mechanism includes a hydraulic oil tank (6) and an adjustment valve (5); An auxiliary liquid chamber (202) is provided inside the inner cylinder body (201). The flexible adjustment structure (203) passes through the auxiliary liquid chamber (202) and is fixedly connected to the inner cylinder body (201) at both ends. An injection port (205) is provided on the side wall of the inner cylinder body (201). The injection port (205) communicates with the auxiliary liquid chamber (202). The injection port (205) is connected to the hydraulic oil tank (6) through a conduit. The adjustment valve (5) is provided on the conduit. The inner cylinder body (201) is provided with stepped mounting holes at both the upper and lower ends. The flexible adjustment structure (203) has an I-shaped longitudinal section, so that the upper and lower protrusions of the flexible adjustment structure (203) can extend into the stepped mounting holes. A pressure plate (204) is threaded into the stepped mounting holes. The pressure plate (204) is used to seal and fix the flexible adjustment structure (203) in the auxiliary liquid chamber (202). The pressure plate (204) has a first communication port with the same diameter as the liquid channel (208), so that the upper liquid chamber (105) and the lower liquid chamber (303) can communicate with the liquid channel (208).

2. The adjustable frequency liquid-elastic vibration isolator as described in claim 1, characterized in that, The upper outer cylinder assembly (1) is also provided with a liquid compensation chamber (103). The liquid compensation chamber (103) is located above the upper liquid chamber (105), and a second communication port is provided between the liquid compensation chamber (103) and the upper liquid chamber (105). The liquid compensation chamber (103) contains a mixture of air and liquid. When the amount of liquid in the upper liquid chamber (105) is insufficient, the liquid in the liquid compensation chamber (103) can be naturally replenished to the upper liquid chamber (105) under the action of gravity.

3. The adjustable frequency liquid-elastic vibration isolator as described in claim 2, characterized in that, The upper outer cylinder assembly (1) includes an upper outer cylinder end cap (102), a liquid replenishment plate (104), and an upper outer cylinder (106) that are fixedly connected from top to bottom. The lower end of the upper outer cylinder end cap (102) and the upper and lower ends of the liquid replenishing plate (104) are provided with grooves, so that the liquid compensation cavity (103) is formed between the upper outer cylinder end cap (102) and the liquid replenishing plate (104). The groove at the lower end of the liquid replenishing plate (104) forms the upper liquid cavity (105). The second communication port is located at the center of the liquid replenishing plate (104). The inner side of the upper outer cylinder (106) is fixedly connected to the outer side of the elastic rubber (4).

4. The adjustable frequency liquid-elastic vibration isolator as described in claim 1, characterized in that, The lower outer cylinder assembly (3) includes a lower outer cylinder (301) and a lower outer cylinder end cap (302) that are fixedly connected. The lower outer cylinder end cap (302) has a groove at its upper end, thereby forming the lower liquid cavity (303). The inner side of the lower outer cylinder (301) is fixedly connected to the outer side of the elastic rubber (4).

5. The adjustable frequency liquid-elastic vibration isolator as described in claim 1, characterized in that, The inner cylinder body (201) is provided with a flange (206) on its outer periphery. A long bolt (101) is provided through the upper outer cylinder assembly (1), the flange (206) and the lower outer cylinder assembly (3). The upper outer cylinder assembly (1) and the lower outer cylinder assembly (3) can be fixedly connected by the long bolt (101) and the nut.

6. A method for adjusting the frequency of an adjustable frequency liquid-elastic vibration isolator according to any one of claims 1-5, characterized in that, The process includes the following: Determine the target isolation frequency of the adjustable frequency liquid-elastic vibration isolator; The target amplification ratio corresponding to the flexible adjustment structure of the liquid-elastic vibration isolator is calculated based on the target vibration isolation frequency. The target amplification ratio is the ratio of the cross-sectional area of ​​the upper or lower liquid cavity to the cross-sectional area of ​​the liquid channel inside the flexible adjustment structure. The change in the target cross-sectional diameter of the internal liquid channel of the flexible adjustment structure is calculated based on the target magnification ratio. The flexible adjustment structure is deformed by a control mechanism, causing the internal liquid channel to change according to the target cross-sectional diameter.

7. A method for adjusting the frequency of an adjustable frequency liquid-elastic vibration isolator according to any one of claims 2-5, characterized in that, The process includes the following: Determine the target isolation frequency of the adjustable frequency liquid-elastic vibration isolator; The target amplification ratio corresponding to the flexible adjustment structure of the liquid-elastic vibration isolator is calculated based on the target vibration isolation frequency. The target amplification ratio is the ratio of the cross-sectional area of ​​the upper or lower liquid cavity to the cross-sectional area of ​​the liquid channel inside the flexible adjustment structure. The target pressure of the hydraulic oil in the auxiliary fluid chamber is calculated based on the target magnification ratio. By controlling the regulating valve, hydraulic oil in the hydraulic oil tank is injected into the auxiliary fluid chamber, so that the pressure of the hydraulic oil in the auxiliary fluid chamber reaches the target pressure.

8. The frequency adjustment method for the adjustable frequency liquid-elastic vibration isolator as described in claim 7, characterized in that, The relationship between the target magnification ratio and the target pressure of the hydraulic oil in the auxiliary fluid chamber is as follows: ； in, Target magnification ratio; The initial cross-sectional diameter of the liquid channel before deformation. Let be the cross-sectional area of ​​the upper and lower liquid cavities. This represents the cross-sectional area of ​​the liquid channel; The target pressure of the hydraulic oil. This is the derivative of the change in diameter of the liquid channel with respect to the pressure, which is related to the material properties and is a constant term here.

Images