A compound damper for a navigation system and a method of operation thereof

Abstract

The application discloses a composite damper for a navigation system and a working method thereof. The composite damper comprises a damping damper and a working cylinder damper. The working cylinder damper comprises a working cylinder and a back pressure valve. A piston in the working cylinder divides a cavity of the working cylinder into a first pressure cavity and a second pressure cavity. The back pressure valve is connected between the first pressure cavity and the second pressure cavity through a pipeline. A spring is arranged between the damping damper and the working cylinder damper. One of the damping damper and the working cylinder damper is arranged on a carrier, and the navigation system is arranged on the other damper. The application further discloses a working method of the composite damper for the navigation system. The application has simple structure, less parts and light weight. In addition, the application can isolate short-time large-scale vibration, impact and overload.

Description

Technical Field

[0001] This invention relates to a vibration damper for a navigation system, and more particularly to a composite vibration damper for a navigation system and its operating method. Background Technology

[0002] Navigation systems generally refer to satellite navigation and positioning systems (GNSS) or inertial navigation and positioning systems (INS), as well as combined navigation systems that integrate the two (and may also incorporate other navigation and positioning information). As positioning, orientation, and attitude measurement components, navigation systems are widely used in various fields such as aircraft, vehicles, ships, underwater vehicles, mines, and tunnels.

[0003] Taking aircraft applications as an example, aircraft are subjected to various excitations during flight, such as engine thrust, air noise, and turbulent boundary layer pulsating pressure. These combined factors generate wide-bandwidth, high-amplitude vibration excitations, placing the aircraft in an environment affected by vibration, shock, and noise during flight. The measurement accuracy of the strapdown inertial navigation system (INS) largely determines the aircraft's navigation accuracy. When these vibrations and shocks are transmitted to the INS mounted on the aircraft, they introduce measurement errors, affecting the accuracy of the INS's attitude measurement. In severe cases, the INS may be damaged, its output may diverge, or even the aircraft may self-destruct. Therefore, designing an effective vibration-damping mounting structure, allowing the INS to sit on the aircraft like a "soft saddle," provides a good dynamic working environment, minimizes measurement errors, and ensures the normal and stable operation of the strapdown INS during flight, allowing it to leverage its high precision advantage. However, current technology mainly addresses the effects of vibration (e.g., a root mean square acceleration of 6.06g). For large shocks (e.g., 100g, 10ms), only data can be discarded, resulting in a sacrifice of some accuracy.

[0004] Satellite navigation systems can generally only withstand short-term overloads (typically 30g for 2 seconds) when receiving satellite signals. Overloads exceeding 30g will cause signal loss, affecting positioning accuracy. Many unmanned aerial vehicles (UAVs) experience overloads exceeding 30g, resulting in even greater acceleration; under such conditions, satellite navigation will become ineffective. Currently, there is no effective solution.

[0005] In mechanical engineering, commonly used vibration dampers include rubber dampers, spring dampers, and pneumatic dampers. Spring dampers have poor damping performance and a low applicable operating frequency range, thus limiting their application. Pneumatic dampers are more complex to produce and use, requiring a pressurized air supply system, and are suitable for vibration damping in large equipment. Rubber dampers have good damping performance and are easy to process, allowing them to be made into various complex shapes. However, rubber vibration isolators cannot effectively isolate impacts or address short-term overloads. In recent years, metal-rubber material vibration dampers have become a research hotspot due to their advantages such as long lifespan, corrosion resistance, fatigue resistance, and aging resistance. However, since metal-rubber is a relatively new vibration damping material, its theoretical basis is not yet fully developed. The structure and characteristics of various vibration dampers are introduced below.

[0006] (1) Rubber vibration damper

[0007] Rubber vibration dampers are small in size and simple in design, and can effectively absorb high-frequency vibration energy. They exhibit moderate performance under tension and shear, good performance under compression, and moderate stability and service life at high temperatures. Rubber vibration dampers are widely used in missile-borne equipment and are the most numerous and widely applicable type of vibration damper among Russian-made vibration dampers.

[0008] Currently, mainstream inertial navigation systems utilize damped rubber vibration isolators. The vibration isolators for the inertial measurement unit (IMU) are designed with a four-point support structure, evenly distributed along the circumference. The vibration isolators are a combination of metal and rubber. The vibration damping system consists of three parts: the IMU, the vibration isolators, and the mounting plate. Bolts connect the vibration isolators to the IMU and the mounting plate. The mounting plate provides a connection interface between the projectile and the IMU. This vibration damping structure reduces the peak value during system resonance and effectively isolates vibrations within a certain frequency range due to the damping material. By rationally designing the height of the limiting sleeve and damping pad, the compression of the rubber damping pad is controlled, and the tightening torque of the mounting bolts is controlled according to certain requirements, ensuring reliable connection of the vibration damping structure and uniform stress on the four support points. However, because it is difficult to make the frequency of this type of vibration isolator very low, it is difficult to achieve attenuation effects for large-scale impacts.

[0009] (2) Pneumatic vibration damper

[0010] Also known as an air spring, it uses compressed air as the elastic element and has advantages such as high flexibility, low natural frequency, and large standard load. However, its production and use are complex, its lateral stiffness is low, and it requires a pressure air supply device. Therefore, pneumatic vibration dampers are more suitable for large equipment or for overall vibration damping of the entire section of a large missile. Pneumatic vibration dampers are nonlinear vibration dampers; their natural frequency is determined by the working pressure of the gas inside the air spring, the structure of the air spring, the inflation volume of the air spring, the effective working area of ​​the air spring, and the effective working radius. Pneumatic vibration dampers have stiffness characteristics that are drastically different from vibration dampers using metal springs, rubber, etc., as elastic bodies, and their natural frequency is significantly lower than that of other vibration dampers.

[0011] (3) Metal spring vibration damper

[0012] Metal spring vibration dampers are unaffected by ambient temperature, can operate under harsh conditions, are easy to maintain, and have a long service life. Therefore, they are widely used on ships. Western countries such as the US, Germany, and France have been actively researching and exploring their application, and China has also achieved considerable success in the development and application of wire rope vibration dampers. While these dampers perform well against large-scale impacts and short-term overloads, their complex composition, large size, and less than ideal damping effect limit their use in navigation equipment.

[0013] (4) Metal-rubber vibration damper

[0014] Metal rubber is a novel damping and vibration reduction material. It is formed by spiraling, stretching, and winding metal wires, followed by molding, resulting in a three-dimensional network structure similar to the polymer structure of natural rubber. Vibration dampers made from it primarily utilize the dry friction damping generated by the relative displacement of the internal metal wires under stress and deformation to dissipate a large amount of vibrational energy, thereby achieving vibration reduction. It possesses advantages such as good damping effect, high strength, high temperature resistance, corrosion resistance, and aging resistance.

[0015] Within a metal-rubber material, the number of contact points between the metal wires determines the dry friction damping performance of the metal-rubber component. External loads can alter the number of contact points, causing corresponding nonlinear changes in the component's stiffness and damping. For cylindrical components, when an external load acts along the component's axis, the contact area between the material's internal layers increases. When the load acts along the shear direction, relative slippage occurs between the contact layers, changing the contact area. This relative slippage between layers forms the dry friction damping within the metal-rubber material, dissipating the vibrational energy of the external load. Under the same operating conditions, the damping ratio of a metal-rubber vibration damper can reach 0.35, significantly higher than that of a conventional rubber vibration damper.

[0016] Currently, several universities and research institutes in China are developing metal rubber materials. Most of them are focused on theoretical research, while a few research institutions are conducting theoretical research and actual design and manufacturing. However, due to the complexity of manufacturing, the product performance is not consistent, and practical applications are still rare.

[0017] CN108458040A discloses an integrated adjustable double-layer vibration damping module, which aims to control equipment vibration through a double-layer vibration damping module and an adjustable intermediate mass. However, its vibration damping module is large in size, heavy in weight, and complex in composition, and is mainly used for vibration and noise reduction of large electromechanical equipment such as ships, making it difficult to meet the application requirements of current navigation systems. In addition, its feedback control system, consisting of a displacement sensor, a pressure sensor, a venting solenoid valve, an inflating solenoid valve, and a controller, is used to control the height between the electromechanical equipment and the foundation, but can only achieve a height control accuracy of ±0.5mm, which also cannot meet the application requirements of navigation systems.

[0018] In summary, most current shock absorber or damper patents are for vehicle systems, and their functionality cannot meet the needs of navigation systems in multiple fields such as aircraft and ships. Furthermore, automotive shock absorbers are large, heavy, and complex in composition, all of which make them difficult to meet the application requirements of current navigation systems. Moreover, existing technologies generally only change the shape of the shock absorber, the layout of the damping material, and the composition of the damping material, lacking breakthroughs in technological thinking. Summary of the Invention

[0019] The purpose of this invention is to overcome the above-mentioned shortcomings of the prior art and provide a composite vibration damper for navigation systems that is simple in composition, lightweight, high in precision, and has good vibration reduction effect, as well as its working method.

[0020] The technical solution of this invention is:

[0021] One aspect of the present invention is a composite vibration damper for a navigation system, comprising a damping vibration damper and a working cylinder vibration damper; the working cylinder vibration damper includes a working cylinder and a back pressure valve; a piston inside the working cylinder divides the cavity of the working cylinder into a first pressure chamber and a second pressure chamber; the back pressure valve is connected between the first pressure chamber and the second pressure chamber via a pipeline; a spring is provided between the damping vibration damper and the working cylinder vibration damper; one of the damping vibration dampers and the working cylinder vibration damper is mounted on a carrier, and the navigation system is placed on the other vibration damper.

[0022] Furthermore, the piston rod connecting the piston is fitted with the spring at the end that extends out of the working cylinder, and the two ends of the spring are fixed between the working cylinder and the piston top.

[0023] Furthermore, the working cylinder is equipped with a stroke sensor to detect the displacement of the cylinder and to compensate for the attitude measurement error and speed / angular velocity error of the navigation system caused by the displacement or inability to reset the cylinder.

[0024] Furthermore, the damping shock absorber includes a damping mandrel and at least two damping blocks symmetrically mounted on the damping mandrel. The damping blocks are fixed to the piston top by damping pads and bolts. The navigation system is installed between the damping blocks.

[0025] Furthermore, the working cylinder is a pneumatic cylinder or a hydraulic cylinder; the damping damper is a rubber damper or a metal-rubber damper; and the stroke sensor is a grating linear position sensor or a resistive linear position sensor.

[0026] A method for operating a composite vibration damper for a navigation system according to the present invention includes the following steps:

[0027] S1: Model the relationship between the back pressure valve pressure setpoint, piston stroke and maximum load of the navigation system to obtain the back pressure valve pressure setpoint p1 and the cylinder piston stroke x0;

[0028] S2: Under initial conditions, the working cylinder is filled with a medium at a predetermined pressure, the back pressure valve is closed, and the rigidity of the working cylinder is much greater than that of the damping shock absorber.

[0029] S3: When under normal vibration, impact and general overload conditions, if the pressure in the working cylinder is less than the pressure setting value p1 of the back pressure valve, the back pressure valve is still closed, and the vibration reduction characteristics of the composite damper are the same as those of the damping damper.

[0030] S4: When certain mechanical conditions are met, the piston moves so that the pressure inside the working cylinder is greater than or equal to the pressure setting value p1 of the back pressure valve. The back pressure valve opens, and the rigidity and damping of the composite damper are changed, suppressing vibration for a short time.

[0031] Furthermore, the natural frequencies of the working cylinder damper and the damping damper do not coincide with the natural frequency of the navigation system, and maintain a difference of more than 50% from the natural frequency of the navigation system.

[0032] Furthermore, in S1, the method for obtaining the pressure setpoint and piston stroke of the back pressure valve is as follows:

[0033] A. The pressure setting value of the back pressure valve is related to the maximum load applied to the working cylinder by the navigation system, as shown in the following formula:

[0034]

[0035]

[0036] In the formula: Pmax p1 is the maximum load applied to the working cylinder by the navigation system; p1 is the pressure setting value of the back pressure valve; A is the effective pressure-bearing area of ​​the working cylinder; p a Standard atmospheric pressure;

[0037] B. The stroke of the working cylinder piston should meet the setting requirements of the rated pressure value of the back pressure valve, as shown in the following formula:

[0038]

[0039]

[0040]

[0041] In the formula: p0 is the absolute air pressure in the working cylinder when it is in static equilibrium position; p1 is the back pressure valve pressure setting value; V0 is the gas volume in the working cylinder when it is in static equilibrium position; V1 is the gas volume in the inner cavity of the working cylinder when it is working; A is the effective pressure bearing area of ​​the working cylinder; x0 is the piston stroke; x1 is the piston displacement when the working cylinder is working.

[0042] Furthermore, in S3, under normal vibration, impact and general overload conditions, the movement of the piston causes the internal pressure of the working cylinder to not reach the pressure setting value of the back pressure valve, and the movement of the piston changes the gas volume of the first pressure chamber and the second pressure chamber, causing the gas in one pressure chamber to expand and the gas in the other pressure chamber to compress, resulting in a damping effect in the cylinder.

[0043] Furthermore, in S4, when the back pressure valve opens, the frequency of the composite damper decreases rapidly, isolating a large number of vibrations, impacts, and overloads in a short time. At the same time, the spring connected between the damping damper and the working cylinder buffers the damage to the working cylinder caused by the instantaneous action. And when the stroke sensor detects that the working cylinder has displacement, it compensates for the attitude measurement error and speed / angular velocity error of the navigation system caused by the displacement or failure to reset of the working cylinder.

[0044] The beneficial effects of this invention are:

[0045] (1) By setting a back pressure valve, on the one hand, the back pressure valve has a simple structure, small weight and small size, which can meet the application requirements of the navigation system; on the other hand, it can reduce the overall composition, that is, the back pressure valve is combined with the cylinder, which can greatly reduce the number of parts, making the structure extremely simple, and also reducing the impact of other components' electronic control on the overall vibration reduction effect; furthermore, it can realize the adaptability of the navigation system in complex mechanical environments, and according to different conditions, the preset pressure value of the back pressure valve can be adjusted to achieve the purpose.

[0046] (2) By combining the back pressure valve with the working cylinder to form a working cylinder damper, on the one hand, it can provide higher rigidity and dynamic response under the requirements of general-level vibration, impact and general overload conditions, while avoiding unnecessary damping. Especially when the navigation system needs higher positioning accuracy and response speed, low damping helps to maintain the dynamic performance of the system. When a certain mechanical condition is reached, the frequency of the composite damper can be reduced rapidly to achieve the purpose of isolating short-term large-scale vibration, impact and overload, and effectively protect the damping damper and navigation system from damage.

[0047] (3) By combining the working cylinder damper with the damping damper, it is possible to isolate a large number of low-frequency mechanical environments and high-frequency mechanical environments, and to protect the damping damper and the working cylinder from damage under large-scale vibration, impact and overload, thereby protecting the navigation system from being affected.

[0048] (4) By setting a spring, damage to the cylinder can be prevented from being caused by excessively fast impact;

[0049] (5) By setting up a stroke sensor, the problem of attitude and speed measurement error caused by changes in cylinder stroke can be solved;

[0050] (6) By obtaining the pressure setting value of the back pressure valve and the maximum stroke of the piston, the basic working performance of the composite damper can be made linear, thereby making the dynamic behavior of the composite damper more stable, easier to model and analyze, reducing the complexity of design and adjustment, and ensuring the long-term stable operation of the composite damper. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of the composite vibration damper of Embodiment 1 of the present invention;

[0052] Figure 2 This is a schematic diagram of the piston stroke of the cylinder in Embodiment 1 of the present invention.

[0053] Explanation of reference numerals in the attached diagram:

[0054] 1. Rubber vibration damper; 2. Cylinder; 3. Back pressure valve; 4. Spring; 5. Navigation system; 11. Vibration damping spindle; 12. Rubber vibration damping block; 13. Vibration damping pad; 21. Piston; 22. Piston rod; 23. Piston top. Detailed Implementation

[0055] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0056] Example 1

[0057] like Figure 1As shown: A composite vibration damper for a navigation system includes a rubber vibration damper 1, a cylinder vibration damper, a spring 4, and a stroke sensor; the cylinder vibration damper includes a cylinder 2 and a back pressure valve 3; the piston 21 in the cylinder 2 divides the cylinder cavity into a first pressure chamber 1# and a second pressure chamber 2#; the back pressure valve 3 is connected between the first pressure chamber 1# and the second pressure chamber 2# via a pipeline; the spring 4 is located between the rubber vibration damper 1 and the cylinder 2; the navigation system 5 is mounted on the rubber vibration damper 1.

[0058] The above solution has the following advantages: The reason this embodiment uses a back pressure valve instead of other solenoid valves is twofold. First, the back pressure valve has a simple structure, is lightweight, and small in size, meeting the application requirements of the navigation system. Second, it reduces the overall composition; combining the back pressure valve with the cylinder significantly reduces the number of parts, making the structure extremely simple and reducing the impact of other components on the overall vibration damping effect. Furthermore, by combining the cylinder, back pressure valve, and rubber vibration damper, this embodiment not only greatly simplifies the structure, saves other parts, and significantly reduces volume and weight, but also greatly improves the vibration damping effect, thereby solving the problem of isolating impacts and the impact of short-term overloads on the navigation system.

[0059] Specifically, in this embodiment, the cylinder 2 is connected to the carrier at the end furthest from the rubber damper 1, thereby mounting the entire composite damper on the carrier. The piston rod 22 extending out of the cylinder 2 is fitted with the spring 4, and the two ends of the spring 4 are fixed between the cylinder 2 and the piston top 23. The spring 4 serves an auxiliary function to prevent damage to the cylinder 2 from excessively rapid impacts.

[0060] In this embodiment, the rubber vibration damper 1 includes a vibration damping mandrel 11 and two rubber vibration damping blocks 12 symmetrically mounted on the vibration damping mandrel, which are then fixed to the piston top by vibration damping pads 13 and bolts. The two rubber vibration damping blocks 12 are fitted onto the vibration damping mandrel 11 one above the other, and the navigation system 5 is installed between the two rubber vibration damping blocks 12. For example, a mounting lug is provided between the two rubber vibration damping blocks, and the navigation system is fixed to the mounting lug.

[0061] In this embodiment, a stroke sensor is mounted on cylinder 2 to detect the displacement of cylinder 2 and to compensate for attitude measurement errors and velocity / angular velocity errors in the navigation system caused by cylinder displacement or failure to reset. Preferably, the stroke sensor is a grating linear position sensor, which can achieve an accuracy of ±1.0μm, and its measurement accuracy can be set to ±0.01μm.

[0062] In this embodiment, the back pressure valve is connected between the first pressure chamber and the second pressure chamber via a pipeline, specifically connected to the top of the first pressure chamber, which can reduce the overall size of the cylinder; and the position connecting to the second pressure chamber should be such that when the internal pressure of the second pressure chamber reaches the set pressure of the back pressure valve, the piston is still above the connection position, so as to avoid the upper and lower connection ports of the back pressure valve from being connected to each other.

[0063] The following are application examples of the composite vibration damper of this invention in navigation systems:

[0064] The navigation system 5 is mounted on the carrier via a composite vibration damper. It can be understood that the navigation system in this embodiment can be mounted on the carrier using a vibration damping system composed of several composite vibration dampers, or it can be mounted on the carrier using a single composite vibration damper. The cylinder and spring of the composite vibration damper are connected in parallel, and then connected in series with a rubber vibration damper to provide support for the navigation system. Under specific mechanical environmental conditions, the back pressure valve releases the pressure inside the cylinder, changing the rigidity of the composite vibration damper, thereby achieving the purpose of vibration reduction, shock isolation, and isolation of short-term large overloads of the navigation system under harsh mechanical environments.

[0065] Under initial conditions, cylinder 2 is filled with a certain pressure of gas. Since the back pressure valve is closed, the air volumes at both ends of the cylinder cannot compensate for each other, which increases the rigidity of the cylinder. This makes the rigidity of the cylinder much greater than that of the rubber damper, thereby enabling the navigation system to have a faster response speed and higher accuracy.

[0066] Under normal vibration, impact, and general overload conditions, with the back pressure valve 3 still closed, the vibration reduction characteristics of the composite damper are mainly the same as those of the rubber damper. It can be said that with the back pressure valve 3 closed, the cylinder does not significantly change the system's stiffness and damping characteristics; the main vibration reduction effect of the composite damper comes from the linear characteristics of the rubber damper. The cylinder still possesses considerable rigidity and, compared to the initial conditions, also has some damping, which can prevent the rubber damper 1 from excessively bearing vibration energy. Moreover, in this state, low damping helps maintain the dynamic performance of the navigation system. However, when certain mechanical conditions are reached (increased vibration, impact, and overload), exceeding the aforementioned general conditions, the back pressure valve 3 opens, allowing gas to flow freely between the first and second pressure chambers, thereby increasing the overall damping. Damping can absorb and disperse the energy of vibration and impact, reducing their impact on the navigation system. Since the composite damper usually has a certain natural frequency, when external vibration or impact forces approach this frequency, resonance is likely to occur, and the amplitude will increase sharply. Opening the back pressure valve alters the dynamic characteristics of the composite vibration damper, causing its frequency to drop rapidly and effectively isolating short-term, high-volume vibrations, impacts, and overloads. The spring connected in parallel with the cylinder primarily serves an auxiliary function, preventing damage to the cylinder from excessively rapid movements. When the stroke sensor detects cylinder displacement, it compensates for attitude measurement errors and velocity / angular velocity errors in the navigation system caused by cylinder displacement or failure to reset.

[0067] The natural frequencies of cylinder 2 and rubber damper 1 should not coincide with the natural frequency of navigation system 5, and should maintain a difference of more than 50% from the natural frequency of navigation system to prevent resonance of cylinder, rubber damper and navigation system, so that cylinder and rubber damper can maintain a good working environment and protect navigation system from damage caused by resonance.

[0068] Based on the above analysis, the working method of the composite vibration damper of the present invention is as follows:

[0069] S101: Model the relationship between the back pressure valve pressure setting value, piston stroke and maximum load of the navigation system to obtain the back pressure valve pressure setting value p1 and the cylinder piston stroke x0; and calculate the natural frequency of the cylinder when it is in the equilibrium position when the back pressure valve is closed and the cylinder stops working (in the equilibrium position).

[0070] Specifically, under normal mechanical conditions, when the cylinder is not working (i.e., the back pressure valve is closed), the rubber damper operates in the linear stiffness range, thus the composite damper's basic operation is linear. Under harsh mechanical conditions, the back pressure valve opens, the cylinder begins to work, protecting the rubber damper and allowing it to continue operating in the linear range. However, the cylinder exhibits nonlinear behavior, which is mainly related to gas density, cylinder displacement, rigidity, cylinder shape parameters, operating environment (such as the maximum load of the navigation system), and the pressure setting of the back pressure valve. Therefore, this embodiment mainly considers the relationship between the back pressure valve pressure setting, the cylinder stroke, and the maximum load of the navigation system, specifically:

[0071] (1) The pressure setting value of the back pressure valve is related to the maximum load applied to the cylinder by the navigation system, and the relationship is as follows:

[0072]

[0073]

[0074] In the formula: P max p1 is the maximum load applied to the cylinder by the navigation system; p1 is the pressure setting value of the back pressure valve (i.e., the maximum absolute air pressure inside the cylinder); A is the effective pressure-bearing area of ​​the cylinder; p a Standard atmospheric pressure.

[0075] (2) The stroke (displacement) of the cylinder should meet the setting requirements of the rated pressure value of the back pressure valve, and the relationship is as follows:

[0076]

[0077]

[0078]

[0079] In the formula: p0 is the absolute air pressure inside the cylinder at the static equilibrium position; p1 is the back pressure valve pressure setting value (i.e., the maximum absolute air pressure inside the cylinder); V0 is the gas volume inside the cylinder at the static equilibrium position; V1 is the gas volume inside the cylinder when it is working; A is the effective pressure-bearing area of ​​the cylinder; x0 is the piston stroke (e.g., ... Figure 2 (as shown), which is the maximum moving distance; x1 is the displacement of the piston when the cylinder is working.

[0080] (3) The natural frequency of the cylinder at the equilibrium position is calculated as follows:

[0081] When the cylinder is in the equilibrium position (i.e., the cylinder is not working):

[0082] V=V0, p=p0, ;

[0083] In the formula, V is the gas volume inside the cylinder; p is the absolute gas pressure inside the cylinder. This represents the effective area change rate.

[0084] That is: the stiffness of the cylinder when it is in the equilibrium position.

[0085] In the formula, e is the polytropic index.

[0086] The natural frequency of the cylinder at the equilibrium position is:

[0087]

[0088] In the formula: g is the acceleration due to gravity.

[0089] This embodiment uses the aforementioned relationship to obtain the pressure setpoint of the back pressure valve and the maximum stroke of the piston, making the basic operation of the composite damper linear. This results in more stable dynamic behavior of the composite damper, facilitating modeling and analysis, reducing design and adjustment complexity, and ensuring long-term stable operation of the composite damper. By obtaining the natural frequency of the cylinder, resonance in the navigation system can be avoided.

[0090] S102: Under initial conditions, the cylinder is filled with a certain pressure gas, and at this time the rigidity of the cylinder is much greater than that of the rubber shock absorber.

[0091] Specifically, because the piston moves slightly up and down during operation, under initial conditions the piston is located near the top of the cylinder, which allows the piston to have sufficient stroke and avoids contact between the piston and the top of the cylinder.

[0092] With the back pressure valve closed, the gas between the first pressure chamber 1# and the second pressure chamber 2# of the cylinder cannot flow to each other. This means that the piston movement is very small under initial conditions. The closed back pressure valve reduces the gas's buffering effect. Because the gas cannot move freely to absorb and disperse external forces, the cylinder's response to external loads becomes more rigid, thus enhancing the cylinder's rigidity. Rubber dampers, due to their high elasticity and flexibility, can effectively absorb and mitigate vibrations and impacts. However, as the cylinder's rigidity increases, the overall rigidity contrast in the system changes. As the cylinder becomes more rigid, its role in the entire vibration damping system becomes more prominent, and its rigidity appears greater than that of the rubber damper.

[0093] S103: When the piston moves under normal vibration, impact and general overload conditions, and the pressure in the working cylinder is less than the pressure setting value p1 of the back pressure valve, the back pressure valve is still closed, and the vibration reduction characteristics of the composite damper are the same as those of the damping damper.

[0094] Specifically, in this embodiment, vibrations of 20-2000Hz and below 6.06g are defined as general-level vibrations, general-level impacts, and ordinary overload conditions. Vibrations exceeding these conditions will generate large-scale vibrations, impacts, and overloads. Under general-level vibration, impact, and ordinary overload conditions, when subjected to a certain amount of vibration, the piston will move up and down within a small range. However, under these conditions, the internal pressure of the cylinder does not reach the pressure setting value of the back pressure valve, and the back pressure valve will not open. When the piston moves upward, the gas in the first pressure chamber 1# is compressed, and the gas in the second pressure chamber 2# expands; when the piston moves downward, the gas in the first pressure chamber 1# expands, and the gas in the second pressure chamber 2# is compressed. It can be said that although the back pressure valve is closed to prevent gas from flowing directly through the pipeline, the movement of the piston will change the gas pressure distribution and produce certain damping characteristics, but these are not significant. Therefore, the vibration reduction characteristics of the composite damper are still the same as those of the rubber damper, while the partial damping characteristics brought by the cylinder can protect the rubber damper 1 from the effects of general-level vibrations and impacts.

[0095] S104: When certain mechanical conditions are met, the piston moves so that the pressure of the back pressure valve is greater than or equal to the pressure set value p1. The back pressure valve opens, changing the rigidity and damping of the composite damper. The frequency of the composite damper decreases rapidly, thereby achieving the purpose of isolating large-scale vibrations, impacts and overloads in a short period of time.

[0096] Specifically, when the load applied to the cylinder by the navigation system reaches the target load, it indicates that the load applied to the cylinder by the navigation system is under conditions of high-level vibration, impact, and overload. Under these mechanical conditions, the back pressure valve opens, allowing the gas inside the cylinder to flow freely under pressure. This significantly enhances the cylinder's vibration suppression effect and significantly improves its damping characteristics, thereby effectively suppressing vibrations in the cylinder and the entire system. It also significantly improves the protection effect on the rubber vibration damper, preventing it from excessively bearing vibration energy. In this embodiment, the piston movement speed is related to the load on the cylinder; the greater the load, the greater the piston movement speed, ranging from 0 to the piston movement speed under the maximum load.

[0097] Example 2

[0098] The difference from Example 1 is that the pneumatic cylinder is replaced with a hydraulic cylinder, such as an oil cylinder, to improve rigidity and damping.

[0099] In this embodiment, the pneumatic cylinder is replaced by a hydraulic cylinder, while the connection method of the back pressure valve remains unchanged. Oil replaces the gas in the pneumatic cylinder, passing through the back pressure valve. Unlike the working medium which is gas, the advantages of using a hydraulic cylinder in this embodiment are: fast response, simpler control and adjustment, and good self-lubrication. However, using a hydraulic cylinder presents certain difficulties under high and low temperature conditions; and to prevent oil leakage, the hydraulic components require high manufacturing precision.

[0100] The other structures are the same as in Example 1, and a hydraulic cylinder is used. The modeling and calculation are performed using the same formula as in Example 1.

[0101] Example 3

[0102] The difference from Embodiment 1 is that the positions of the rubber damper and the cylinder are interchanged. That is, the rubber damper is installed on the carrier, and the cylinder is installed on the top of the rubber damper. The back pressure valve is still connected between the first pressure chamber and the second pressure chamber of the cylinder. The cylinder is inverted compared to Embodiment 1, that is, the piston top of the cylinder is connected to the rubber damper. The spring is still connected between the rubber damper and the cylinder. The navigation system is installed on the cylinder.

[0103] The working principle of this structure is the same as that of Embodiment 1, and compared with the navigation system being located on the rubber damper, it can avoid the impact of high-frequency vibration on the cylinder.

[0104] Example 4

[0105] The difference from Example 1 is that the rubber damper is replaced with other types of damping dampers, such as metal-rubber dampers.

[0106] The other structures are the same as in Example 1, and will not be described in detail here.

[0107] In summary, the present invention has two advantages: firstly, the composite vibration damper is simple in composition, has few parts, and is lightweight; secondly, it can isolate a large number of low-frequency mechanical environments as well as a large number of high-frequency mechanical environments.

Claims

1. A composite vibration damper for a navigation system, characterized in that, The system includes a damping damper and a working cylinder damper. The working cylinder damper includes a working cylinder and a back pressure valve. A piston inside the working cylinder divides the cylinder's cavity into a first pressure chamber and a second pressure chamber. The back pressure valve is connected between the first and second pressure chambers via a pipeline. The damping damper includes a damping mandrel and at least two damping blocks symmetrically mounted on the mandrel. The damping blocks are fixed to the piston top by damping pads and bolts. A spring is provided between the damping damper and the working cylinder damper. One of the dampers is mounted on a carrier, while the navigation system is placed on the other damper. A stroke sensor is provided on the working cylinder to detect its displacement and to compensate for navigation system attitude measurement errors and velocity or angular velocity errors caused by the working cylinder's displacement or inability to reset.

2. The composite vibration damper for a navigation system according to claim 1, characterized in that, The piston rod connected to the piston has the spring fitted at the end that extends out of the working cylinder, and the two ends of the spring are fixed between the working cylinder and the piston top.

3. The composite vibration damper for a navigation system according to claim 1, characterized in that, The navigation system is installed between the vibration damping blocks.

4. The composite vibration damper for a navigation system according to claim 1, characterized in that, The working cylinder is a pneumatic cylinder or a hydraulic cylinder; the damping damper is a rubber damper or a metal-rubber damper; the stroke sensor is a grating linear position sensor or a resistive linear position sensor.

5. A method for operating a composite vibration damper for a navigation system according to claim 1, characterized in that, Includes the following steps: S1: Model the relationship between the back pressure valve pressure setpoint, piston stroke and maximum load of the navigation system to obtain the back pressure valve pressure setpoint p1 and the working cylinder piston stroke x0; S2: Under initial conditions, the working cylinder is filled with a medium at a predetermined pressure, the back pressure valve is closed, and the rigidity of the working cylinder is much greater than that of the damping shock absorber. S3: When under normal vibration, impact and general overload conditions, if the pressure in the working cylinder is less than the pressure setting value p1 of the back pressure valve, the back pressure valve is still closed, and the vibration reduction characteristics of the composite damper are the same as those of the damping damper. S4: When certain mechanical conditions are met, the piston moves so that the pressure inside the working cylinder is greater than or equal to the pressure setting value p1 of the back pressure valve. The back pressure valve opens, and the rigidity and damping of the composite damper are changed, suppressing vibration for a short time.

6. The method of operating the composite vibration damper for a navigation system according to claim 5, characterized in that, The natural frequencies of the working cylinder damper and the damping damper do not coincide with the natural frequency of the navigation system, and maintain a difference of more than 50% from the natural frequency of the navigation system.

7. The method of operating the composite vibration damper for a navigation system according to claim 5 or 6, characterized in that, In S1, the method for obtaining the pressure setpoint and piston stroke of the back pressure valve is as follows: A. The pressure setting value of the back pressure valve is related to the maximum load applied to the working cylinder by the navigation system, as shown in the following formula: ; ; In the formula: P max p1 is the maximum load applied to the working cylinder by the navigation system; p1 is the pressure setting value of the back pressure valve; A is the effective pressure-bearing area of ​​the working cylinder; p a Standard atmospheric pressure; B. The stroke of the working cylinder piston should meet the setting requirements of the rated pressure value of the back pressure valve, as shown in the following formula: ; ; ; In the formula: p0 is the absolute air pressure in the working cylinder when it is in static equilibrium position; p1 is the back pressure valve pressure setting value; V0 is the gas volume in the working cylinder when it is in static equilibrium position; V1 is the gas volume in the inner cavity of the working cylinder when it is working; A is the effective pressure bearing area of ​​the working cylinder; x0 is the piston stroke; x1 is the piston displacement when the working cylinder is working.

8. The method of operating the composite vibration damper for a navigation system according to claim 5 or 6, characterized in that, In S3, under normal vibration, impact and general overload conditions, the movement of the piston causes the internal pressure of the working cylinder to not reach the pressure setting value of the back pressure valve, and the movement of the piston changes the gas volume of the first pressure chamber and the second pressure chamber, causing the gas in one pressure chamber to expand and the gas in the other pressure chamber to compress, resulting in a damping effect in the working cylinder.

9. The method of operating the composite vibration damper for a navigation system according to claim 5 or 6, characterized in that, In S4, when the back pressure valve opens, the frequency of the composite damper decreases rapidly, isolating a large number of vibrations, impacts, and overloads in a short time. At the same time, the spring connected between the damper and the working cylinder buffers the damage to the working cylinder caused by the instantaneous action. Furthermore, when the stroke sensor detects that the working cylinder has displaced, it compensates for the attitude measurement error and speed or angular velocity error of the navigation system caused by the displacement or failure to reset of the working cylinder.

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