A passive anti-shock parallel platform

Abstract

The present invention discloses a passive anti-shock parallel platform, comprising a dynamic platform, a variable damper, a variable stiffness isolator, a static platform, a lower ball seat, an overshoot protector, and an upper ball seat. The dynamic platform is connected to an inertial navigation device, and the static platform is connected to a ship hull. The dynamic platform and the static platform are connected via a variable damper and a variable stiffness isolator. The lower ball seat is disposed on the surface of the static platform, and the upper ball seat is disposed on the surface of the dynamic platform. Through the synergistic effect of the variable damper and the variable stiffness isolator, the present invention enables the platform to efficiently absorb and consume impact energy. The damping force of the variable damper increases with the increase in displacement of the offset equilibrium position, effectively weakening the response of the dynamic platform and quickly helping it return to the equilibrium position. The multi-stage vibration isolation design of the variable stiffness isolator enables the platform to absorb the initial impact energy with a lower stiffness when impacted, and then limit the generation of large displacement with a higher stiffness, further improving the impact resistance.

Description

Technical Field

[0001] The present invention belongs to a protective device for ship inertial navigation equipment, in particular to a passive anti-shock parallel platform. Background Art

[0002] Ships are essential equipment for conducting maritime military operations, maintaining the security of sea lanes, and safeguarding national maritime interests. Strong combat capabilities and sustained battlefield viability are essential for defeating the enemy. In the complex, information-based, and modernized combat environment, ships are subject not only to direct enemy attack but also to the reaction forces of their own weapons. Therefore, unless significant damage is sustained to the ship's structure and functions, its sustained combat capability depends primarily on the impact resistance of its onboard equipment. If this equipment fails to meet the impact resistance requirements during combat, damage will inevitably lead to the ship's collapse. Therefore, shock isolation and protection of core shipboard equipment are crucial for victory in modern naval warfare.

[0003] Inertial navigation equipment (INS) is the core equipment that provides information on the ship's position, attitude, speed, and heading. It has a complex mechanical structure and numerous high-precision electronic components. It is essential equipment to ensure the safety and continuous combat capability of the ship and is rated A in terms of impact protection. Unlike other shipborne equipment, INS has more stringent requirements for vibration isolation. This is mainly reflected in the following: when the hull is subjected to a more severe impact, the safety of the INS equipment should be protected as much as possible, and the isolation device should play a good buffering role and absorb the impact load; when the ship is sailing normally and is subject to minor disturbances such as waves, the rigidity of the connection between the INS and the hull should be guaranteed to meet the INS's need for sensitive attitude; at the same time, the isolation device should also have a rapid reset function.

[0004] To protect shipborne inertial navigation systems (INS), a shock isolation device must be connected in series between the ship and the INS. Currently, using a parallel mechanism as the main structure of the isolation device is an effective method for addressing multi-dimensional vibration and shock, and has been widely used. Depending on whether or not a control system is included, these vibration isolation devices can be categorized as active compensation platforms and passive buffer platforms. Each has its own advantages and disadvantages in practical applications, addressing the multi-dimensional and less predictable external shocks encountered during ship navigation. Compared to active compensation platforms, passive buffer platforms are purely mechanical devices with simpler structures, lower costs, easier maintenance, and no need for a control system. They utilize multiple passive elastic damping branches connected in parallel between the upper and lower platforms to mitigate external shocks. Without exceeding the stroke of the elastic damping branches, they can significantly attenuate high-frequency, high-amplitude external shocks, offering fast response, safety, and reliability, making them particularly suitable for protecting equipment from high-frequency, high-amplitude shock loads such as explosions. However, a disadvantage is that the stability of the upper platform cannot be autonomously controlled. Limited by its inherent properties, the overall stiffness of the device is nearly fixed, making it difficult to meet the specific shock isolation requirements of INS equipment. If the stiffness of the elastic damping branch chain, the core component of the impact isolation platform, can be automatically adjusted according to the excitation load without the intervention of the control system, it will maintain rigidity when subjected to low-frequency and low-amplitude load excitation, and show good buffering and energy absorption effects when subjected to high-frequency and high-amplitude impact loads, providing reliable support stiffness and being able to effectively perform overshoot protection to avoid secondary impacts, it will be able to better meet the impact resistance requirements of shipborne inertial navigation and provide it with effective impact protection.

[0005] The main structure of a parallel shock isolation device used to protect shipboard equipment consists of upper and lower platforms, with multiple elastic damping branches connected in parallel between them. To improve the platform's vibration reduction performance, researchers at home and abroad have conducted research on various aspects, including structural configuration, branch structure, and the elastic damping medium of the shock absorbers, achieving fruitful results. The core of the shock-resistant platform is a parallel mechanism connected in series between the ship's deck and the equipment. Therefore, the structure of this parallel mechanism plays a crucial role in the impact resistance. Parallel mechanisms are spatial multi-loop, multi-degree-of-freedom mechanisms. By permuting and combining multiple single-open chains or mixed single-open chains, parallel mechanism configurations with different degrees of freedom and motion characteristics can be obtained. Different configurations have a direct impact on the platform's vibration reduction and buffering performance. For example, Ma Luzhong, Yin Xiaoqin, and others from Jiangsu University have experimentally verified that a 3-3 Stewart platform with spring dampers (gas-liquid mixers) as branches can attenuate acceleration shocks to 1 / 20 of their original value and return to equilibrium within a short period of time, effectively solving the problem of multi-dimensional vibration reduction. Tang Weixing, Zhu Wei, and others have conducted extensive research on other parallel mechanisms, including a five-degree-of-freedom parallel mechanism with three translations and two rotations, a three-translation parallel mechanism, and a four-degree-of-freedom parallel vibration reduction platform. The offshore drilling platform developed by the Norwegian company AASMEK effectively isolates the deck from roll, pitch, and heave. Shenyang University of Technology and the Naval Research Institute have proposed eight- and six-link passive impact isolators, with the links being traditional spring-damped branched chains.

[0006] Through research, it was found that the passive anti-shock parallel platform currently proposed does not have the function of adjusting stiffness and damping during the impact process. In the face of the special protection objects such as inertial navigation (when the hull is subjected to a more severe impact, the safety of the inertial navigation equipment should be protected as much as possible, and the isolation device should play a good buffering role to absorb the impact load; when the ship is sailing normally and is subjected to minor disturbances such as waves, the rigidity of the connection between the inertial navigation and the hull should be guaranteed to meet the inertial navigation's sensitive attitude requirements), in the absence of a control system, it is necessary to have the ability to change both stiffness and damping coefficients to better protect the inertial navigation equipment from damage by impact loads and ensure good working performance.

[0007] Most existing passive, impact-resistant parallel platforms use dampers with fixed damping values, which are unable to dynamically adjust the damping force based on the impact intensity. This results in a lack of flexibility in the platform's response to impacts of varying intensities, making it difficult to effectively limit the platform's deflection while quickly restoring it to its equilibrium position. Summary of the Invention

[0008] Purpose of the invention: In order to overcome the deficiencies in the prior art, the purpose of the present invention is to provide a passive anti-shock parallel platform that can efficiently absorb impact energy, ensure high-precision measurement, enhance structural flexibility, have strong ultimate impact resistance, and ensure equipment safety.

[0009] Technical solution: The passive anti-shock parallel platform described in the present invention includes a dynamic platform, a variable damper, a variable stiffness shock isolator, a static platform, a lower ball seat, an overshoot protector and an upper ball seat. The dynamic platform and the static platform are connected through the variable damper and the variable stiffness shock isolator. The lower ball seat is arranged on the static platform, the upper ball seat is arranged on the dynamic platform, and the overshoot protector is arranged between the dynamic platform and the static platform.

[0010] Furthermore, the lower ball seat and the upper ball seat are respectively arranged at both ends of the variable damper or at both ends of the variable stiffness shock isolator, and the variable stiffness shock isolator is located outside the variable damper.

[0011] Furthermore, the number of the variable dampers and the variable stiffness shock isolators are equal and are all arranged obliquely.

[0012] Furthermore, the variable damper includes a lower ball head, an upper ball head, a flange surface locking nut, a damping cylinder base plate, a damping cylinder, a damping piston rod and a damping cylinder end cover. The damping cylinder base plate and the damping cylinder end cover are respectively located at the two ends of the damping cylinder. The lower ball head is connected to the damping cylinder base plate and is locked by the flange surface locking nut. One end of the damping piston rod is located inside the damping cylinder, and the other end passes through the through hole in the center of the damping cylinder end cover and is connected to the upper ball head.

[0013] Furthermore, hydraulic oil is provided inside the damping cylinder, and the thickness of the inner wall of the damping cylinder presents a piecewise linear change, with the inner wall thickness being the thinnest at the center of the damping cylinder and gradually increasing at both ends.

[0014] Furthermore, the variable stiffness isolator includes a first ball head, a hexagon socket screw, a cylinder body, a cylinder body spring bottom plate, a first-stage vibration-isolating spring, a second-stage vibration-isolating spring retaining ring, a first-stage vibration-isolating spring spacer, a rear end cover of a pull rod, a pull rod, an upper end cover of a cylinder body, a second ball head washer, a second ball head, an upper end cover of a piston cylinder, a piston cylinder, a pull rod spring spacer, a pull rod spring, a second-stage vibration-isolating spring guide rod end cover, a second-stage vibration-isolating spring, a second-stage vibration-isolating spring guide rod, an isolator bottom plate and a flange surface locking nut. The upper end cover of the cylinder body and the isolator bottom plate are respectively located at both ends of the cylinder body, the first ball head is connected to the isolator bottom plate, the isolator bottom plate is connected to the cylinder body spring bottom plate, and the cylinder body spring bottom plate is connected to the first The second-stage vibration-proof spring guide rod is connected, the second-stage vibration-proof spring and the second-stage vibration-proof spring retaining ring are sleeved on the outside of the second-stage vibration-proof spring guide rod, the second-stage vibration-proof spring guide rod is connected to the second-stage vibration-proof spring guide rod end cover, the first-stage vibration-proof spring and the first-stage vibration-proof spring spacer are both located inside the cylinder body, the first-stage vibration-proof spring is respectively located on both sides of the first-stage vibration-proof spring spacer, the piston cylinder is nested in the cylinder body and connected to the upper end cover of the piston cylinder, one end of the pull rod is connected to the second ball head, and the other end is connected to the rear end cover of the pull rod, the second ball head washer is located between the pull rod and the second ball head, the pull rod spring spacer and the pull rod spring are both located in the piston cylinder, and the pull rod spring is located on both sides of the pull rod spring spacer.

[0015] Furthermore, the length of the guide rod of the second-stage vibration-isolating spring is slightly greater than the natural length of the second-stage vibration-isolating spring. The first-stage vibration-isolating spring is connected to the cylinder spring base plate or the piston cylinder. The sum of the natural lengths of the first-stage vibration-isolating springs is greater than the internal length of the cylinder, and the sum of the natural lengths of the pull rod springs is greater than the internal length of the piston cylinder.

[0016] Furthermore, the lower ball seat and the upper ball seat have the same structure. The lower ball seat includes a ball seat base, a ball cover and a hinged hole bolt. The ball seat base is connected to the ball cover. The interior of the ball seat base and the ball cover are both provided with a ball cavity that matches the ball head. The hinged hole bolt is arranged on the surface of the ball seat base.

[0017] Furthermore, the overshoot protector includes an overshoot protector movable rod, an overshoot protector end cover, an overshoot protector fixing tube and an overshoot protector rubber. The overshoot protector fixing tube is connected to the static platform, the overshoot protector rubber is arranged in the overshoot protector fixing tube, the overshoot protector end cover is connected to the overshoot protector fixing tube, one end of the overshoot protector movable rod is connected to the dynamic platform, and the other end is located inside the overshoot protector fixing tube.

[0018] Working principle: The dynamic platform is fixedly connected to the inertial navigation device to support and fix the inertial navigation device. The static platform is fixedly connected to the hull and serves as the fixed foundation of the entire shock-resistant parallel platform. The dynamic platform and the static platform are connected through a variable damper and a variable stiffness isolator. These connectors cooperate with the ball joints through the lower ball seat and the upper ball seat to allow the dynamic platform to have a certain degree of freedom of movement when it is impacted. When the hull is impacted, the static platform is disturbed, and the variable damper and the variable stiffness isolator start to work to absorb and consume the impact energy. The variable damper is filled with hydraulic oil, and the thickness of its inner wall increases with the distance from the equilibrium position, thereby providing a gradually increasing damping force. When impacted, the damping piston rod deviates from the equilibrium position, causing the hydraulic oil to generate greater flow resistance through the thickened inner wall, thereby absorbing and consuming the impact energy. Among them, the variable stiffness isolator has a two-stage vibration isolation system, including a first-stage vibration isolation spring. Spring and second-stage vibration isolation spring. In the initial stage, the equivalent stiffness of the shock isolator is K1, which is provided by the two first-stage vibration isolation springs in series. As the impact increases, the first-stage vibration isolation spring spacer contacts the second-stage vibration isolation spring retaining ring, thereby squeezing the second-stage vibration isolation spring. At this time, the equivalent stiffness of the shock isolator changes to K2, which helps to limit the occurrence of large displacement. After the impact, the spring begins to rebound, and the equivalent stiffness of the shock isolator gradually returns to K1. Finally, after the piston cylinder contacts the upper end cover of the cylinder body, it becomes K3, which is provided by the pull rod spring. When the shock-resistant parallel platform is subjected to excessive impact load, the overshoot protector movable rod will collide with the overshoot protector rubber, which absorbs the impact load, providing overshoot protection for the structure and preventing a hard collision between the moving platform and the static platform. As the impact weakens, the variable damper and variable stiffness shock isolator gradually return to their initial state, the moving platform also returns to the equilibrium position, and the inertial navigation equipment continues to operate stably.

[0019] Beneficial effects: Compared with the prior art, the present invention has the following significant features:

[0020] 1. Through the synergistic effect of the variable damper and the variable stiffness isolator, the platform can efficiently absorb and dissipate impact energy. The damping force of the variable damper increases with the displacement of the offset equilibrium position, effectively weakening the dynamic platform's response and quickly helping it return to the equilibrium position. The multi-stage vibration isolation design of the variable stiffness isolator enables the platform to absorb the initial impact energy with lower stiffness when impacted, and then limit large displacement with higher stiffness, further improving impact resistance.

[0021] 2. The dynamic platform is fixedly connected to the inertial navigation equipment. Precision-designed variable-rigidity shock isolators provide stable and precise support for the equipment, helping to ensure high-precision measurements when the ship's hull is impacted. The series and parallel combination of the first-stage and second-stage vibration-isolating springs in the variable-rigidity shock isolators enables the platform to automatically adjust its stiffness based on the impact intensity, thereby maintaining overall structural stability. By adjusting the thickness of the first-stage spring spacer ring, the initial compression of the first-stage spring can be fine-tuned to meet the varying rigidity and support requirements of the equipment.

[0022] 3. The design of the lower and upper ball seats allows the ball head to rotate smoothly in the ball cavity without disengagement, which increases the motion range of the ball head and enables the variable damper and variable stiffness isolator to be flexibly installed and adapt to different impact directions;

[0023] 4. The design of the overshoot protector effectively prevents hard collisions between the dynamic platform and the static platform, improving the equipment's ultimate impact resistance. The overshoot protector rubber can absorb impact loads, provide overshoot protection for the structure, and further protect the safety of the inertial navigation equipment and the entire parallel platform structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of the present invention;

[0025] Figure 2 It is a structural schematic diagram of the variable damper 2 of the present invention;

[0026] Figure 3 2 is a cross-sectional view of the structure of the variable stiffness shock isolator 3 of the present invention;

[0027] Figure 4 It is a structural schematic diagram of the lower ball seat 5 of the present invention;

[0028] Figure 5 It is a structural schematic diagram of the upper ball seat 7 of the present invention;

[0029] Figure 6 It is a structural diagram of the overshoot protector 6 of the present invention;

[0030] Figure 7 It is a cross-sectional view of the overshoot protector 6 of the present invention. DETAILED DESCRIPTION

[0031] like Figure 1A passive, impact-resistant parallel platform designed to carry inertial navigation equipment weighing no more than 60 kg. Measuring 1000 mm × 1000 mm × 548 mm and weighing 85 kg, it comprises a dynamic platform 1, a variable damper 2, a variable stiffness isolator 3, a static platform 4, a lower ball seat 5, an overshoot protector 6, and an upper ball seat 7. The dynamic platform 1 is fixedly connected to the inertial navigation equipment, supporting and securing it. The static platform 4 is fixedly connected to the hull and serves as the fixed foundation for the entire impact-resistant parallel platform. The dynamic platform 1 and the static platform 4 are connected via eight variable dampers 2 and eight variable stiffness isolators 3, effectively isolating and cushioning impacts on the hull. The lower ball seat 5 is fixedly mounted on the surface of the static platform 4. Both the lower ball seat 5 and the upper ball seat 7 are divided into two groups: one group connects to the ends of the variable damper 2 via ball joints, while the other group connects to the ends of the variable stiffness isolator 3 via ball joints. In the initial state, the angle between the variable stiffness shock isolator 3 and the static platform 4 is approximately 45° (the actual angle is determined by the installation position of the ball socket, and the deviation angle does not exceed ±1°), and the angle between the variable damper 2 and the static platform 4 is approximately 75° (the actual angle is determined by the installation position of the ball socket). The variable stiffness shock isolator 3 is located on the outside of the variable damper 2 in terms of layout. The number of variable dampers 2 and variable stiffness shock isolators 3 are both 8. The overshoot protector 6 is fixedly installed at the center position between the dynamic platform 1 and the static platform 4 to prevent hard collisions between the dynamic platform 1 and the static platform 4, thereby improving the ultimate impact resistance of the equipment, protecting the safety of the inertial navigation equipment and the entire parallel platform structure, and preventing the platform from causing excessive deformation and damage to the main body after being subjected to large longitudinal and lateral impacts.

[0032] Existing shock-resistant parallel platforms mostly consist of 6 or 8 rods. In contrast, the 8-rod arrangement is symmetrical, providing equal attenuation in both the lateral and longitudinal directions. The 6-rod structure, arranged in an equilateral triangle, exhibits different attenuation effects in the lateral and longitudinal directions. Because damping plays a crucial role in shock resistance, the damping effect would be limited if only 8 spring isolators were deployed. Therefore, this embodiment employs a 16-rod structure, comprising 8 variable-stiffness isolators 3 and 8 variable dampers 2.

[0033] like Figure 2The variable damper 2 includes a lower ball head 21, an upper ball head 22, a flange-mounted locking nut 23, a damping cylinder base plate 24, a damping cylinder 25, a damping piston rod 26, and a damping cylinder end cap 27. The damping cylinder base plate 24 and the damping cylinder end cap 27 are located at either end of the damping cylinder 25 and are fixedly connected to the damping cylinder 25 via flanges. Sealing gaskets are placed on the flange end faces to prevent hydraulic oil leakage. The lower ball head 21 is fixedly connected to the damping cylinder base plate 24 and locked with the flange-mounted locking nut 23. One end of the damping piston rod 26 is slidably mounted inside the damping cylinder 25, and the other end passes through the through hole in the center of the damping cylinder end cap 27 and is fixedly connected to the upper ball head 22. The interior of the damping cylinder 25 is filled with hydraulic oil. In order to provide different damping forces at different stages of impact, the inner wall thickness of the damping cylinder 25 shows a piecewise linear change. At the equilibrium position, the inner wall of the damping cylinder 25 is the thinnest, and the damping force is the smallest at this time. When impacted, the damping piston rod 26 will deviate from the equilibrium position. As the deviation increases, the inner wall thickness of the damping cylinder 25 gradually increases, thereby providing a greater damping force. According to the annular gap flow differential equation:

[0034]

[0035] in: (pitch radius of the middle layer of the annular gap); D is the inner diameter of the damping cylinder 25; D0 is the piston head diameter of the damping piston rod 26; (gap); l is the piston head length; n is the flow index; k is the viscosity coefficient. The damping force can be calculated:

[0036]

[0037] Where v is the piston velocity. This design helps reduce the displacement of the dynamic platform after an impact, helping it quickly recover to a balanced position. When impacted, as the deflection of the damping piston rod increases, the damping force also increases, effectively absorbing and dissipating the impact energy and protecting the inertial navigation equipment from damage.

[0038] like Figure 3The variable stiffness shock isolator 3 includes a first ball head 31, a hexagon socket screw 32, a cylinder body 33, a cylinder body spring base plate 34, a first-stage vibration-isolating spring 35, a second-stage vibration-isolating spring retaining ring 36, a first-stage vibration-isolating spring spacer 37, a rear end cover 38 of a pull rod, a pull rod 39, an upper end cover 310 of the cylinder body, a second ball head washer 311, a second ball head 312, an upper end cover 313 of a piston cylinder, a piston cylinder 314, a pull rod spring spacer 315, a pull rod spring 316, a second-stage vibration-isolating spring guide rod end cover 317, a second-stage vibration-isolating spring 318, a second-stage vibration-isolating spring guide rod 319, a shock isolator base plate 320 and a flange surface locking nut 321. The cylinder upper end cap 310 and the isolator base plate 320 are fixedly mounted at each end of the cylinder 33. The first ball head 31 is fixedly connected to the isolator base plate 320 and locked with a hexagon socket screw 32. The isolator base plate 320 is fixedly connected to the cylinder spring base plate 34. The cylinder spring base plate 34 is fixedly connected to one end of the second-stage vibration-isolating spring guide rod 319. The second-stage vibration-isolating spring 318 and the second-stage vibration-isolating spring retaining ring 36 are mounted on the outside of the second-stage vibration-isolating spring guide rod 319. The other end of the second-stage vibration-isolating spring guide rod 319 is fixedly connected to the second-stage vibration-isolating spring guide rod end cap 317. The piston cylinder 314 is nested within the cylinder 33, with one end fixedly connected to the piston cylinder upper end cap 313. The pull rod 39 is fixedly connected to the second ball head 312 at one end and to the pull rod rear end cap 38 at the other end. The second ball head washer 311 is located between the pull rod 39 and the second ball head 312. There is a threaded hole at one end of the pull rod 39. The upper ball head 22 is fixedly connected to the pull rod 39 with the second ball head washer 311 in the form of a threaded connection. The other end of the pull rod 39 has an external thread and is fixedly connected to the rear end cover 38 of the pull rod.

[0039] In the initial installation state, one of the two first-stage vibration-isolating springs 35 is nested within the cylinder spring base 34 to reduce radial deformation, while the other is nested within the piston cylinder 314. Movement of the piston cylinder 314 compresses the first-stage vibration-isolating spring 35. Because the sum of the free lengths of the two first-stage vibration-isolating springs 35 is greater than the effective installation length of the cylinder 33, the first-stage vibration-isolating springs 35 are compressed in their natural state after the variable-rigidity shock isolator 3 is installed. This ensures that the piston cylinder 314, under the restoring force of the first-stage vibration-isolating springs 35, remains firmly attached to the cylinder upper end cap 310. Based on the structural dimensions and calculated for a full load of 70 kg (i.e., the inertial navigation system weighs 60 kg and the dynamic platform weighs 10 kg), the initial support force T provided by each variable-rigidity shock isolator 3 is 70 g / (8·sin45°), and the initial compression Δs1 of the first-stage vibration-isolating spring 35 is 70 g / (8·k1·sin45°), effectively supporting the inertial navigation system. To ensure the rigidity of the inertial navigation system's connection to the hull during normal navigation, even under minor disturbances such as waves, and to meet the inertial navigation system's posture sensitivity requirements, the initial compression Δs1 of the first-stage vibration-isolating spring 35 must be greater than 70g / (8·k1·sin45°). This requires fine-tuning based on the impact level and weight of the equipment. Adjustment can be achieved by simply replacing the first-stage vibration-isolating spring spacer 37 with different thicknesses to achieve different initial compressions for the first-stage vibration-isolating spring 35.

[0040] To achieve a change in the stiffness of the shock isolator during impact, a second-stage vibration-isolating spring retaining ring 36 is designed to move axially on the second-stage vibration-isolating spring guide rod 319, squeezing the second-stage vibration-isolating spring 318. Because the length of the second-stage vibration-isolating spring guide rod 3-19 is slightly shorter than the natural length of the second-stage vibration-isolating spring 318, the second-stage vibration-isolating spring retaining ring 36 acts as a limiter for the second-stage vibration-isolating spring 318. Furthermore, the presence of the second-stage vibration-isolating spring guide rod end cap 317 prevents the second-stage vibration-isolating spring retaining ring 36 from separating from the second-stage vibration-isolating spring guide rod 319. The stiffness of the second-stage vibration-isolating spring 318 is k2. After the impact is transmitted from the hull to the static platform 4, it is further transmitted upward through the lower ball head 31, compressing the two first-stage vibration-isolating springs 35. At this time, the equivalent stiffness of the shock isolator is K1 = k1 / 2. After further compression of the first-stage vibration-isolating springs 35, the first-stage vibration-isolating spring spacer 37 contacts the second-stage vibration-isolating spring retaining ring 36, compressing the second-stage vibration-isolating spring 318. At this time, the two first-stage vibration-isolating springs 35 in the shock isolator are connected in series and in parallel with the second-stage vibration-isolating spring 318. The equivalent stiffness of the shock isolator is now K2 = (k1 + 2k2) / 2. This increased stiffness helps limit further large displacement, absorbs impact energy, and improves the rate of return to equilibrium.

[0041] Furthermore, to prevent secondary impacts, two tie rod springs 316 are designed to fit over the outer wall of the tie rod assembly and are separated by a tie rod spring spacer 315. In their natural state, the tie rod springs 316 are compressed, ensuring that the ball washer 311 rests tightly against the piston cylinder upper end cap 313. When the springs are compressed to their limit and begin to rebound, the equivalent stiffness of the shock isolator changes, gradually recovering from K2 to K1. Ultimately, after the piston cylinder 314 contacts the cylinder upper end cap 310, it reaches K3 = k3 / 2, where k3 represents the stiffness of a single tie rod spring 316. This design further mitigates the impact of shock loads and improves the stability and reliability of the shock isolator.

[0042] like Figures 4-5 The lower ball seat 5 and the upper ball seat 7 have the same structure, each comprising a ball seat base 51, a ball cover 52, and a hinged hole bolt 53. The ball seat base 51 is connected to the ball cover 52. Both the ball seat base 51 and the ball cover 52 have a spherical cavity that mates with the ball head. The ball seat base 51 is fixed to the surfaces of the dynamic platform 1 and the static platform 4 by the hinged hole bolt 53. To accommodate the installation requirements of the variable damper 2 and the variable stiffness shock isolator 3 and increase the range of motion of the ball head, the ball cover 52 is designed with two tilt angles: a 45° ball cover and a -45° ball cover. These two ball covers are used to form a symmetrical pair of lower ball seats 5 and upper ball seats 7. That is, in each pair of adjacent lower ball seats 5 (or upper ball seats 7), one uses a 45° ball cover and the other uses a -45° ball cover. The two are arranged symmetrically to ensure that the ball head can rotate smoothly within the ball cavity and will not disengage. Platforms with different structural parameters will have different angles.

[0043] The upper ball seat 7 is used to connect to the second ball head 312 of the variable damper 2 and the variable stiffness isolator 3 in the form of a ball joint, and mainly includes: a ball seat, an upper ball cover and a hinged hole bolt. The ball seat and the upper ball cover have a ball cavity inside, the size of which matches the second ball head 312. The ball seat and the upper ball cover are fixedly connected by a threaded connection, enclosing the second ball head 312 in the ball cavity. The second ball head 312 can rotate arbitrarily in the ball cavity but will not disengage the ball cavity, thus forming a ball joint. The ball seat and the upper ball cover are fixed to the dynamic platform 1 as a whole by hinged hole bolts.

[0044] like Figures 6-7The overshoot protector 6 includes an overshoot protector movable rod 61, an overshoot protector end cover 62, an overshoot protector fixed cylinder 63 and an overshoot protector rubber 64. The overshoot protector fixed cylinder 63 is fixedly connected to the static platform 4, the overshoot protector rubber 64 is installed inside the overshoot protector fixed cylinder 63, and the overshoot protector end cover 62 is fixedly connected to the overshoot protector fixed cylinder 63 through a flange. One end of the overshoot protector movable rod 61 is fixedly connected to the dynamic platform 1, and the other end is located inside the overshoot protector fixed cylinder 63. When the impact-resistant parallel platform is subjected to a lateral or longitudinal impact load, the overshoot protector movable rod 61 will collide with the overshoot protector rubber 64, and the overshoot protector rubber 64 will absorb the impact load to protect the structure from overshoot.

Claims

1. A passive anti-shock parallel platform, characterized by: The invention comprises a moving platform (1), a variable damper (2), a variable stiffness shock isolator (3), a static platform (4), a lower ball seat (5), an overshoot protector (6) and an upper ball seat (7); the moving platform (1) and the static platform (4) are connected via the variable damper (2) and the variable stiffness shock isolator (3); the lower ball seat (5) is arranged on the static platform (4); the upper ball seat (7) is arranged on the moving platform (1); and the overshoot protector (6) is arranged between the moving platform (1) and the static platform (4); The variable stiffness shock isolator (3) comprises a first ball head (31), a hexagon socket screw (32), a cylinder body (33), a cylinder body spring base plate (34), a first-stage vibration-isolating spring (35), a second-stage vibration-isolating spring retaining ring (36), a first-stage vibration-isolating spring spacer (37), a pull rod rear end cover (38), a pull rod (39), a cylinder body upper end cover (310), a second ball head washer (311), a second ball head (312), a piston cylinder upper end cover (313), a piston cylinder (314), a pull rod spring spacer (315), a pull rod Rod spring (316), second-stage vibration-isolating spring guide rod end cover (317), second-stage vibration-isolating spring (318), second-stage vibration-isolating spring guide rod (319), isolator bottom plate (320) and flange surface locking nut (321), the cylinder upper end cover (310) and isolator bottom plate (320) are respectively located at both ends of the cylinder (33), the first ball head (31) is connected to the isolator bottom plate (320), the isolator bottom plate (320) is connected to the cylinder spring bottom plate (34), the cylinder spring bottom plate (34 ) is connected to the second-stage vibration-proof spring guide rod (319), the second-stage vibration-proof spring (318) and the second-stage vibration-proof spring retaining ring (36) are sleeved on the outside of the second-stage vibration-proof spring guide rod (319), the second-stage vibration-proof spring guide rod (319) is connected to the second-stage vibration-proof spring guide rod end cover (317), the first-stage vibration-proof spring (35) and the first-stage vibration-proof spring spacer (37) are both located inside the cylinder body (33), and the first-stage vibration-proof spring (35) is respectively located on both sides of the first-stage vibration-proof spring spacer (37). On the other side, the piston cylinder (314) is nested in the cylinder body (33) and connected to the upper end cover (313) of the piston cylinder, one end of the pull rod (39) is connected to the second ball head (312), and the other end is connected to the rear end cover (38) of the pull rod, the second ball head washer (311) is located between the pull rod (39) and the second ball head (312), the pull rod spring spacer (315) and the pull rod spring (316) are both located in the piston cylinder (314), and the pull rod spring (316) is located on both sides of the pull rod spring spacer (315).

2. The passive anti-shock parallel platform according to claim 1, characterized in that: The lower ball seat (5) and the upper ball seat (7) are respectively arranged at two ends of the variable damper (2) or at two ends of the variable stiffness shock isolator (3); the variable stiffness shock isolator (3) is located outside the variable damper (2).

3. The passive anti-shock parallel platform according to claim 1, characterized in that: The variable dampers (2) and the variable stiffness shock isolators (3) are equal in number and are all arranged at an angle.

4. The passive anti-shock parallel platform according to claim 1, characterized in that: The variable damper (2) comprises a lower ball head (21), an upper ball head (22), a flange surface locking nut (23), a damping cylinder base plate (24), a damping cylinder (25), a damping piston rod (26) and a damping cylinder end cover (27), wherein the damping cylinder base plate (24) and the damping cylinder end cover (27) are respectively located at two ends of the damping cylinder (25), the lower ball head (21) is connected to the damping cylinder base plate (24) and is locked by the flange surface locking nut (23), one end of the damping piston rod (26) is located inside the damping cylinder (25), and the other end passes through the through hole in the center of the damping cylinder end cover (27) and is connected to the upper ball head (22).

5. The passive anti-shock parallel platform according to claim 4, characterized in that: Hydraulic oil is provided inside the damping cylinder (25), and the thickness of the inner wall of the damping cylinder (25) presents a segmented linear change, wherein the inner wall thickness of the damping cylinder (25) is the thinnest at the center and gradually increases at both ends.

6. The passive anti-shock parallel platform according to claim 1, characterized in that: The length of the second-stage vibration-isolating spring guide rod (319) is slightly greater than the natural length of the second-stage vibration-isolating spring (318).

7. The passive anti-shock parallel platform according to claim 1, characterized in that: The first-stage vibration-isolating spring (35) is connected to the cylinder spring base plate (34) or the piston cylinder (314), the sum of the natural lengths of the first-stage vibration-isolating spring (35) is greater than the internal length of the cylinder (33), and the sum of the natural lengths of the pull rod spring (316) is greater than the internal length of the piston cylinder (314).

8. The passive anti-shock parallel platform according to claim 1, characterized in that: The lower ball seat (5) and the upper ball seat (7) have the same structure. The lower ball seat (5) comprises a ball seat base (51), a ball cover (52) and a hinged hole bolt (53). The ball seat base (51) is connected to the ball cover (52). The interiors of the ball seat base (51) and the ball cover (52) are both provided with a ball cavity matched with the ball head. The hinged hole bolt (53) is provided on the surface of the ball seat base (51).

9. The passive anti-shock parallel platform according to claim 1, characterized in that: The overshoot protector (6) comprises an overshoot protector movable rod (61), an overshoot protector end cover (62), an overshoot protector fixing cylinder (63) and an overshoot protector rubber (64); the overshoot protector fixing cylinder (63) is connected to the static platform (4); the overshoot protector rubber (64) is arranged in the overshoot protector fixing cylinder (63); the overshoot protector end cover (62) is connected to the overshoot protector fixing cylinder (63); one end of the overshoot protector movable rod (61) is connected to the dynamic platform (1); and the other end is located inside the overshoot protector fixing cylinder (63).

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