Passive anti-impact parallel platform

Abstract

The invention discloses a passive anti-impact parallel platform which comprises a movable platform, a variable damper, a variable stiffness impact isolator, a static platform, a lower ball seat, an overshoot protector and an upper ball seat, the movable platform is connected with inertial navigation equipment, the static platform is connected with a ship body, the movable platform and the static platform are connected through the variable damper and the variable stiffness impact isolator, and the upper ball seat is connected with the overshoot protector. The lower ball seat is arranged on the surface of the static platform, and the upper ball seat is arranged on the surface of the movable platform. Through the synergistic effect of the variable dampers and the variable-stiffness impact isolators, the platform can efficiently absorb and consume impact energy, the damping force of the variable dampers is increased along with the increase of displacement of the offset balance position, the response of the movable platform is effectively weakened, the movable platform is rapidly helped to recover to the balance position, and due to the multi-stage anti-vibration design of the variable-stiffness impact isolators, the damping force of the variable dampers is reduced. Therefore, when the platform is impacted, initial impact energy can be absorbed with low rigidity, then generation of large displacement is limited with higher rigidity, and the impact resistance is further improved.

Description

Technical Field

[0001] The 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 important equipment for carrying out maritime military combat missions, maintaining the security of sea lanes, and safeguarding national maritime interests. Having strong combat effectiveness and sustained battlefield vitality are necessary factors for defeating the enemy. In the complex combat environment of informatization and modernization, ships will not only suffer direct attacks from the enemy, but also withstand the reaction force brought about by the launch of their own weapons. Therefore, when the structure and functions of the ship itself are not seriously damaged, its sustained combat capability is mainly reflected in the impact resistance of the shipborne equipment. If the shipborne equipment cannot meet the impact resistance requirements during combat, the ship will inevitably be paralyzed due to equipment damage. Therefore, impact isolation and protection of core shipborne equipment is the key to victory in modern naval battles.

[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 many high-precision electronic components. It is an essential device to ensure the safety and continuous combat capability of the ship, and is rated as Class A in the impact protection level. Unlike other shipborne equipment, INS has more stringent requirements for vibration isolation, which is mainly reflected in: 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 slight disturbances such as waves, the rigidity of the connection between the INS and the hull should be guaranteed to meet the INS's sensitive attitude requirements; at the same time, the isolation device should also have a fast reset function.

[0004] In order to protect the shipborne inertial navigation system, an impact isolation device needs to be connected in series between the ship and the inertial navigation system. At present, using the parallel mechanism as the main structure of the isolation device is an effective method to solve multi-dimensional vibration and impact, and has been widely used. According to whether it contains a control system, this type of vibration isolation device can be divided into two categories: active compensation platform and passive buffer platform. Facing the external impact with multiple dimensions and weak predictability during the navigation of the ship, they have their own advantages and disadvantages in practical applications. Compared with the active compensation platform, the passive buffer platform is a purely mechanical device with a simple structure, low cost, easy maintenance, and no need for a control system. It uses multiple passive elastic damping branches in parallel between the upper and lower platforms to weaken the external impact. Under the premise of not exceeding the stroke of the elastic damping branch chain, it can greatly weaken high-frequency and high-amplitude external impacts, with fast response speed, safety and reliability, and is more suitable for protecting instruments and equipment from high-frequency and high-amplitude impact loads such as explosions. The disadvantage is that the stability of the upper platform cannot be controlled autonomously. It is limited by its inherent properties, and the overall stiffness of the equipment is almost fixed, which makes it difficult to meet the special needs of impact isolation of inertial navigation 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, and 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, and provide reliable support stiffness, and can 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 the parallel impact isolation device used to protect ship equipment is composed of an upper and lower platform and multiple elastic damping branches connected in parallel between them. In order to improve the vibration reduction effect of the platform, domestic and foreign researchers have conducted research from multiple aspects such as structural configuration, branch chain structure, and elastic damping medium of the shock absorber, and have achieved fruitful results. The core of the anti-shock platform is the parallel mechanism connected in series between the ship deck and the equipment. Therefore, the structural form of the parallel mechanism plays a vital role in the anti-shock effect. The parallel mechanism belongs to a spatial multi-ring multi-degree-of-freedom mechanism. By arranging and combining multiple single-open chains or mixed single-open chains, parallel mechanism configurations with different degrees of freedom and different motion characteristics can be obtained. Different configurations have a direct impact on the vibration reduction and buffering effect of the platform. For example, Ma Luzhong, Yin Xiaoqin and others from Jiangsu University found through experimental verification that the 3-3 Stewart platform with a spring damper (gas-liquid mixer) as a branch chain can attenuate the acceleration shock to 1 / 20 of the original, and can return to a balanced state in a short time, which solves the problem of multi-dimensional vibration reduction very well. Tang Weixing, Zhu Wei and others have conducted many studies on parallel mechanisms of other structural forms, including three-translation and two-rotation five-DOF parallel mechanisms, three-translation parallel mechanisms, four-DOF parallel vibration reduction platforms, etc. The offshore drilling platform developed by the Norwegian AASMEK company can play a good role in isolating the roll, pitch and heave of the deck; Shenyang University of Technology and the Naval Research Institute proposed eight-link and six-link passive anti-impact isolators, and the connecting rods are traditional spring damping branch chains.

[0006] Through research, it is 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 and absorb the impact load; when the ship is sailing normally and is subjected to slight 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 stiffness and damping coefficient at the same time to better protect the inertial navigation equipment from damage by impact loads and have good working performance.

[0007] Most existing passive anti-shock parallel platforms use dampers with fixed damping values, which cannot dynamically adjust the damping force according to the impact intensity. This results in the platform's response being inflexible when subjected to impacts of varying intensities, making it difficult to effectively limit the displacement of the dynamic platform and quickly help it return to a balanced 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 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 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 two ends of the variable damper or at two ends of the variable stiffness shock isolator, and the variable stiffness shock isolator is located outside the variable damper.

[0011] Furthermore, the number of variable dampers and variable stiffness isolators is equal and they are all inclined.

[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 two ends of the damping cylinder. The lower ball head is connected to the damping cylinder base plate and is locked by a 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 arranged inside the damping cylinder, and the thickness of the inner wall of the damping cylinder presents a piecewise linear change, wherein the inner wall thickness at the center of the damping cylinder is the thinnest and gradually increases 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-proof spring, a second-stage vibration-proof spring retaining ring, a first-stage vibration-proof 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 gasket, 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-proof spring guide rod end cover, a second-stage vibration-proof spring, a second-stage vibration-proof spring guide rod, an isolator bottom plate and a flange surface locking nut, the upper end cover of a cylinder body and the isolator bottom plate are respectively located at two ends of a 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 gasket 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 second-stage vibration-proof spring guide rod is slightly greater than the natural length of the second-stage vibration-proof spring. The first-stage vibration-proof spring is connected to the cylinder spring bottom plate or the piston cylinder, the sum of the natural lengths of the first-stage vibration-proof spring is greater than the internal length of the cylinder, and the sum of the natural lengths of the pull rod spring 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 fixed cylinder and an overshoot protector rubber. The overshoot protector fixed cylinder is connected to the static platform, the overshoot protector rubber is arranged in the overshoot protector fixed cylinder, the overshoot protector end cover is connected to the overshoot protector fixed cylinder, one end of the overshoot protector movable rod is connected to the dynamic platform, and the other end is located inside the overshoot protector fixed cylinder.

[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 as the fixed foundation of the entire impact-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 joint 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 impacted. The hull is impacted, causing the static platform to be disturbed, and the variable damper and variable stiffness isolator start to work to absorb and consume 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 produce a 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-isolating spring. In the initial stage, the equivalent stiffness of the isolator is K1, which is provided by two first-stage vibration-isolating springs in series. As the impact increases, the first-stage vibration-isolating spring spacer ring contacts the second-stage vibration-isolating spring retaining ring, and then squeezes the second-stage vibration-isolating spring. At this time, the equivalent stiffness of the isolator becomes K2, which helps to limit the generation of large displacement. After the impact, the spring begins to rebound, and the equivalent stiffness of the isolator gradually returns to K1, and finally becomes K3 after the piston cylinder contacts the upper end cover of the cylinder body, which is provided by the pull rod spring. When the impact-resistant parallel platform is subjected to excessive impact load, the overshoot protector active rod will collide with the overshoot protector rubber, and the rubber absorbs the impact load to protect the structure from overshoot, preventing the moving platform from hard collision with the static platform. As the impact weakens, the variable damper and the variable stiffness isolator gradually return to the 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 consume impact energy. The damping force of the variable damper increases with the increase of the displacement of the offset equilibrium position, effectively weakening the response of the dynamic platform and quickly helping it to 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 the generation of large displacement with higher stiffness, further improving the impact resistance;

[0021] 2. The dynamic platform is fixedly connected to the inertial navigation device, and the precisely designed variable stiffness isolator provides stable and precise support for the inertial navigation device, which helps to ensure that the inertial navigation device can still maintain high-precision measurement when the hull is impacted. The series and parallel combination of the first-stage vibration-isolating spring and the second-stage vibration-isolating spring in the variable stiffness isolator enables the platform to automatically adjust the stiffness according to the impact intensity, thereby maintaining the stability of the overall structure. By adjusting the thickness of the first-stage vibration-isolating spring spacer ring, the initial compression of the first-stage vibration-isolating spring can be fine-tuned to meet the different requirements of the equipment for rigidity and support force.

[0022] 3. The design of the lower ball seat and the upper ball seat allows the ball head to rotate smoothly in the ball cavity without being disengaged, 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 collision between the dynamic platform and the static platform, and improves the ultimate impact resistance of the equipment. The overshoot protector rubber can absorb the impact load and provide overshoot protection for the structure, further protecting the safety of the inertial navigation equipment and the entire parallel platform structure. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0026] Figure 3 is a structural cross-sectional view 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 schematic diagram of the structure 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 anti-shock parallel platform is used to carry an inertial navigation device with a mass not exceeding 60kg. The overall size is 1000mm×1000mm×548mm, and the curb weight is 85kg. It includes 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 device and is used to support and fix the inertial navigation device. The static platform 4 is fixedly connected to the hull as the fixed foundation of the entire anti-shock parallel platform. The dynamic platform 1 and the static platform 4 are connected through eight variable dampers 2 and eight variable stiffness isolators 3 to effectively isolate and buffer the impact on the hull. The lower ball seat 5 is fixedly installed on the surface of the static platform 4. The lower ball seat 5 and the upper ball seat 7 are divided into two groups. One group of the lower ball seat 5 and the upper ball seat 7 are respectively connected to the two ends of the variable damper 2 through a ball joint, and the other group is respectively connected to the two ends of the variable stiffness isolator 3 through a ball joint. In the initial state, the angle between the variable stiffness isolator 3 and the static platform 4 is about 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 about 75° (the actual angle is determined by the installation position of the ball socket). The variable stiffness isolator 3 is located outside the variable damper 2 in terms of layout. The number of variable dampers 2 and variable stiffness isolators 3 is 8. The overshoot protector 6 is fixedly installed at the center between the moving platform 1 and the static platform 4 to prevent hard collision between the moving 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 being damaged by excessive deformation after being subjected to large longitudinal and lateral impacts.

[0032] The existing anti-shock parallel platforms are mostly 6-rod and 8-rod. In comparison, the 8-rod arrangement is symmetrical and has the same weakening effect in the horizontal and vertical directions. The 6-rod structure is arranged in an equilateral triangle, and has different weakening effects in the horizontal and vertical directions. Since damping plays an important role in resisting impact, if only 8 spring isolators are arranged, the damping is limited. Therefore, this embodiment adopts a 16-rod structure, that is, 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 surface locking nut 23, a damping cylinder bottom plate 24, a damping cylinder 25, a damping piston rod 26 and a damping cylinder end cover 27. The damping cylinder bottom plate 24 and the damping cylinder end cover 27 are respectively located at both ends of the damping cylinder 25, and are both fixedly connected to the damping cylinder 25 through flanges. A sealing gasket is placed on the end surface of the flange to prevent leakage of hydraulic oil. The lower ball head 21 is fixedly connected to the damping cylinder bottom plate 24 and locked by the flange surface locking nut 23. One end of the damping piston rod 26 is slidably installed 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 fixedly connected to the upper ball head 22. 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 presents 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 circle 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 length of the piston head; n is the flow index; k is the viscosity coefficient. The damping force can be calculated:

[0036]

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

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

[0039] In the initial installation state, one of the two first-stage vibration-proof springs 35 is inserted into the cylinder spring bottom plate 34 to reduce the deformation of the spring along its own radial direction, and the other is inserted into the piston cylinder 314. When the piston cylinder 314 moves, it will squeeze the first-stage vibration-proof spring 35. Since the sum of the free lengths of the two first-stage vibration-proof springs 35 is greater than the effective installation length of the cylinder 33, the first-stage vibration-proof spring 35 is compressed in the natural state after the entire variable stiffness isolator 3 is installed, ensuring that the piston cylinder 314 is tightly attached to the cylinder upper end cover 310 under the restoring force of the first-stage vibration-proof spring 35. According to the structural dimensions, according to the full load condition of 70kg (i.e., the weight of the inertial navigation device is 60kg and the moving platform is 10kg), the initial support force T provided by each variable stiffness isolator 3 is 70g / (8·sin45°), and the initial compression amount Δs1 of the first-stage vibration-proof spring 35 is 70g / (8·k1·sin45°), so that the inertial navigation device can be effectively supported. In order to ensure the rigidity of the connection between the inertial navigation system and the hull under slight disturbances such as waves during normal navigation, and to meet the requirements of the inertial navigation system for posture sensitivity, the initial compression Δs1 of the first-stage vibration-proof spring 35 must be greater than 70g / (8·k1·sin45°), and the specific situation needs to be fine-tuned according to the impact level and weight of the equipment. The adjustment method can directly replace the first-stage vibration-proof spring spacer 37 of different thicknesses to achieve different initial compressions of the first-stage vibration-proof spring 35.

[0040] In order to achieve the change of the stiffness of the shock isolator during the impact process, a second-stage vibration isolator is designed. The second-stage vibration isolator spring retaining ring 36 can move axially on the second-stage vibration isolator spring guide rod 319 to squeeze the second-stage vibration isolator spring 318. Since the length of the second-stage vibration isolator spring guide rod 3-19 is slightly shorter than the natural length of the second-stage vibration isolator spring 318, the second-stage vibration isolator spring retaining ring 36 has a limiting effect on the second-stage vibration isolator spring 318. At the same time, due to the existence of the second-stage vibration isolator spring guide rod end cover 317, the second-stage vibration isolator spring retaining ring 36 will not be separated from the second-stage vibration isolator spring guide rod 319. Among them, the stiffness of the second-stage vibration isolator spring 318 is k2. When the impact is transmitted from the hull to the static platform 4, it will be further transmitted upward by the lower ball head 31, and the two first-stage vibration-proof springs 35 will be squeezed. At this time, the equivalent stiffness of the shock isolator is K1=k1 / 2; after further squeezing the first-stage vibration-proof spring 35, the first-stage vibration-proof spring spacer 37 contacts the second-stage vibration-proof spring retaining ring 36, and the second-stage vibration-proof spring 318 is squeezed. At this time, the two first-stage vibration-proof springs 35 in the shock isolator are connected in series and in parallel with the second-stage vibration-proof spring 318. At this time, the equivalent stiffness of the shock isolator is K2=(k1+2k2) / 2. After the stiffness is increased, it helps to limit the further large displacement, and helps to absorb the impact energy and increase the rate of restoring balance.

[0041] In addition, to avoid secondary impact, the two tie rod springs 316 are designed to be sleeved on the outer wall of the tie rod assembly and separated by the tie rod spring spacer 315. In the natural state, the tie rod spring 316 is compressed, ensuring that the ball head gasket 311 is tightly attached to the piston cylinder upper end cover 313. When the spring is compressed to the limit and begins to rebound, the equivalent stiffness of the isolator will change, gradually recovering from K2 to K1, and finally becoming K3=k3 / 2 after the piston cylinder 314 contacts the cylinder upper end cover 310, where k3 is the stiffness of a single tie rod spring 316. This design further weakens the impact of the impact load and improves the stability and reliability of the isolator.

[0042] like Figures 4-5 The lower ball seat 5 and the upper ball seat 7 have the same structure, both of which include 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 inside of the ball seat base 51 and the ball cover 52 are both provided with a ball cavity that matches the ball head. The ball seat base 51 is fixedly mounted on the surface of the dynamic platform 1 and the static platform 4 through the hinged hole bolt 53. In order to meet the installation requirements of the variable damper 2 and the variable stiffness 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 respectively used to form a pair of lower ball seats 5 and upper ball seats 7 of symmetrical structures, 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 in a symmetrical manner to ensure that the ball head can rotate smoothly in the ball cavity and will not disengage. The angle will be different for platforms with different structural parameters.

[0043] The upper ball seat 7 is used to connect with 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. A ball cavity is opened inside the ball seat and the upper ball cover, and the size matches the second ball head 312. The ball seat and the upper ball cover are fixedly connected by a threaded connection, and the second ball head 312 is wrapped in the ball cavity. The second ball head 312 can rotate arbitrarily in the ball cavity, but will not fall out of the ball cavity, thereby forming a ball joint. The ball seat and the upper ball cover are fixed to the moving 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 moving 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 in that: The invention comprises a moving 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 moving platform (1) and the static platform (4) are connected via the variable damper (2) and the variable stiffness 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).

2. A 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 isolator (3); the variable stiffness 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 variable stiffness 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 bottom plate (24), a damping cylinder (25), a damping piston rod (26) and a damping cylinder end cover (27). The damping cylinder bottom 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 bottom 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 arranged inside the damping cylinder (25), and the thickness of the inner wall of the damping cylinder (25) presents a piecewise 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 variable stiffness isolator (3) comprises a first ball head (31), a hexagon socket screw (32), a cylinder body (33), a cylinder body spring bottom plate (34), a first-stage vibration-proof spring (35), a second-stage vibration-proof spring retaining ring (36), a first-stage vibration-proof 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 ... The cylinder body (33) comprises a rod spring (316), a second-stage vibration-proof spring guide rod end cover (317), a second-stage vibration-proof spring (318), a second-stage vibration-proof spring guide rod (319), a buffer bottom plate (320) and a flange surface locking nut (321); the cylinder body upper end cover (310) and the buffer bottom plate (320) are respectively located at two ends of the cylinder body (33); the first ball head (31) is connected to the buffer bottom plate (320); the buffer bottom plate (320) is connected to the cylinder body spring bottom plate (34); the cylinder body 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 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 gasket (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).

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

8. The passive anti-shock parallel platform according to claim 6, 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).

9. 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 hole-making bolt (53). The ball seat base (51) is connected to the ball cover (52). The insides of the ball seat base (51) and the ball cover (52) are both provided with a ball cavity matched with the ball head. The hole-making bolt (53) is arranged on the surface of the ball seat base (51).

10. 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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