431results about How to "Lower natural frequency" patented technology

The invention discloses a load-bearing adjustable zero-stiffness electromagnetic vibration isolator and a control method thereof. An electromagnetic spring of the vibration isolator in the perpendicular direction is composed of three permanent magnets and two groups of controllable direct current electromagnets, two magnets have opposite polarity and generate repulsive force, and stiffness of theelectromagnetic spring can be adjusted by changing and controlling current. An electromagnetic spring of the vibration isolator in the horizontal direction is composed of two groups of symmetrically distributed electromagnetic springs, and stiffness of the electromagnetic spring can be adjusted by changing and controlling current. When the system load-bearing weight is changed, the stiffness of the perpendicular electromagnetic spring and the stiffness of the horizontal electromagnetic spring are led to meet a certain proportional relationship by adjusting and controlling current so that stiffness of the system at the balance position can be zero. When a vibration isolation device is in small vibration near the balance position, dynamic stiffness is very small, and natural frequency of the whole system is very low so that the vibration isolator can achieve wide-range frequency vibration isolation and has good low frequency vibration isolation effect. In addition, the vibration isolator is compact in structure, light in weight and convenient to control.

The invention provides a three degree of freedom micro-vibration suppression platform and a control method thereof, belongs to vibration isolation and suppression devices, and solves problems of complicated structure and complex control method of a prior active-passive composite vibration isolation structure. The platform provided by the invention includes a base platform, a load platform, three sets of single degree of freedom active-passive composite vibration isolation assemblies which are totally identical and a controller. The upper end and the lower end of each single degree of freedom active-passive composite vibration isolation assembly are connected with the load platform and the base platform. The control method provided by the invention includes calculating logic axis translation signals, calculating logic axis control signals, calculating physical axis real time control signals and transmission steps. The platform provided by the invention is simple in structure, adjustable in rigidity, is capable of suppressing and isolating three degree of freedom microvibration in rotation directions of an X axis and a Y axis and a translation direction of a Z axis and is suitable for different occasions. Microvibration of different frequency bands can be dampened effectively and reliable guarantee can be provided for precision machining and measurement equipment in a microvibration environment.

The invention relates to a vertical-vibration horizontal-swinging type power generation device of a low frequency large amplitude piezoelectric cantilever beam, which belongs to the technical field of new energy and power generation. A casing is installed on a base through screws, and a first group of magnets and a second group of magnets are evenly bonded to the inner wall of the casing. A first spring, an inertia block and a second spring are sequentially sleeved on a pin roll from top to bottom. One end of a piezoelectric vibrator is connected with a magnet in bonding mode, and the other end of the piezoelectric vibrator is inserted in a direct groove of the inertia block. The first group of magnets and the second group of magnets and the magnet installed on the piezoelectric vibrator are installed with the same poles close to each other. The power generation device has the advantages of utilizing the environment to vibrate vertically to enable the piezoelectric vibrator of the cantilever beam to swing horizontally in the horizontal level, being capable of achieving low frequency large amplitude vibration energy recycle and being high in reliability.

The invention relates to a multidimensional vibration energy collector capable of realizing non-contact excitement, and belongs to the technical field of new energy and electrical generation. Connecting seats are respectively arranged on an upper top surface and a lower bottom surface of a shell body, and are used for fixing piezoelectric vibrators, and the piezoelectric vibrators are fixed on the connecting seats through screws; each piezoelectric vibrator is formed by adhering a metal substrate and a piezoelectric wafer, and a magnet is arranged at an end part of the piezoelectric vibrator; a tension spring is arranged on the upper top surface of the shell body, a pressure spring is arranged on the lower bottom surface of the shell body, the other ends of the tension spring and the pressure spring are respectively connected with mass blocks, and magnets are embedded around the mass blocks; and the magnets at end parts of the piezoelectric vibrators and the magnets embedded on the mass blocks are arranged in such a manner that homopolar magnet poles are opposite to each other. The multidimensional vibration energy collector capable of realizing non-contact excitement has the advantage that low-frequency and large-amplitude vibration energy in any direction can be collected.

A composite vibration isolation system utilizes isolators with negative-stiffness mechanisms to produce low vertical and horizontal natural frequencies to the system by allowing both the horizontal stiffness and horizontal natural frequencies to be adjusted, for example, by turning adjustment screws.

The invention provides a precise vibration isolation system which comprises a first layer of vibration isolator, a second layer of vibration isolator and a micrometric displacement detector; the first layer of vibration isolator is formed by connecting a first air spring and a magnetorhelogical fluid vibration isolation device in parallel, and the second layer of vibration isolator is formed by connecting a second air spring and a micrometric actuating element in parallel; the second layer of vibration isolator is arranged above the first layer of vibration isolator, and the first layer of vibration isolator and the second layer of vibration isolator are connected in series to be an integral; the micrometric displacement detector is connected with the magnetorhelogical fluid vibration isolation device of the first layer of vibration isolator, and the micrometric actuating element is connected with a vibration measurement sensor; a precise instrument is arranged above the second layer of vibration isolator and connected with the micrometric displacement detector by a vibration measurement light path. By adopting a double layer vibration isolation structure based on control by the micrometric actuating element, the invention can meet the requirement of the precise instrument on low frequency vibration isolation noise reduction and greatly improve anti-vibration capacity of the precise instrument.

The invention relates to a self-adaption stiffness characteristic motion decoupling three-dimensional earthquake/vibration isolation support. The support mainly includes an upper connecting plate, anintermediate plate, a lower connecting plate, a disc spring, a compression spring, pre-pressing springs, a laminated lead core rubber bearing and viscous dampers. The upper connecting plate, the intermediate plate and the lower connecting plate are made of high-strength low-carbon steel and have high bearing capacity. The upper connecting plate and the intermediate plate are engaged with each other to play a motion guiding role. The disc spring, the compression spring, the pre-pressing springs, the laminated lead core rubber bearing and the viscous dampers together form a vertical earthquake/vibration isolation system. The laminated lead core rubber bearing, the pre-pressing springs and the viscous dampers form a horizontal earthquake/vibration isolation system. The invention belongs to apassive self-adaption vibration control method, can be used for buildings affected by environmental vibration, and can isolate seismic oscillation while isolating the environment vibration.

The invention discloses an annular permanent magnet low frequency vibration isolation mechanism based on a negative stiffness theory. The mechanism comprises an upper rubber sheet, an inner annular permanent magnet fixing mandrel, an upper rubber sheet upper pressing ring, an upper rubber sheet outer pressing ring, an outer annular permanent magnet, a lower rubber sheet, a lower rubber sheet inner pressing sheet, a lower rubber sheet outer pressing ring, an outer annular permanent magnet fixing sleeve and an inner annular permanent magnet, wherein the inner annular permanent magnet is magnetized axially; the outer annular permanent magnet is radially magnetized; a positive stiffness system consists of the inner annular permanent magnet and the outer annular permanent magnet; a negative stiffness system consists of the upper rubber sheet and the lower rubber sheet; and the positive stiffness system and the negative stiffness system are used in parallel to form the low frequency vibration isolation mechanism. Three or four single-degree-of-freedom vibration isolation mechanisms are used in parallel to realize three-degree-of-freedom low frequency vibration isolation. When the vibration isolation mechanism has the largest magnetic force, the stiffness of the vibration isolation mechanism approximates to zero. Without an outside air source, the vibration isolation mechanism has a prospect of being used in vacuum, has the characteristics of simple structure and low cost, is easy to process, and can be applied to the fields of optics, acoustics, biologics, semiconductor manufacturing, precise measurement and the like.

The invention mainly belongs to the field of aeronautical engineering, and particularly relates to a quick-disassembling energy absorption undercarriage for a multi-rotor unmanned aerial vehicle. The undercarriage comprises an undercarriage supporting rod, a fixing structure, a quick-disassembling structure and an energy absorption structure. An undercarriage body is fixed to an arm of the multi-rotor unmanned aerial vehicle. The fixing structure and one end of the undercarriage supporting rod are connected or disconnected through the quick-disassembling structure. The energy absorption structure is connected with the other end of the undercarriage supporting rod and comprises energy absorption springs, and conversion of kinetic energy to elastic potential energy can be achieved. The quick-disassembling energy absorption undercarriage is an important part of the multi-rotor unmanned aerial vehicle, is suitable for ground parking, taking-off and landing of the multi-rotor unmanned aerial vehicle and can bear the gravity of the multi-rotor unmanned aerial vehicle and consume and absorb impact and jolt energy during landing of the multi-rotor unmanned aerial vehicle.

The air spring ultra low frequency vibration separation method and device based on the differential electromagnetic actuator includes the air feed system, the high controlling system, a group of the air spring, the basal body, the electromagnetic actuator which not only provides the negative rigidity but the controlled damping force for the system, the speed sensor, the force sensor, the displacement sensor, the power amplifier, the model/number convertor, the number/model convertor and the controller. The invention provides the negative rigidity and the controlled initiative damping force by the reciprocity of the differential electromagnetic and the gag bit fixed on the basal body and the ground separately which is used in the field of high need for the cross-portrait ultra low frequency vibration separation capability.

The invention discloses a combined vibration damping device. The combined vibration damping device comprises a pedestal, a bearing structure, an inerter, a positive stiffness component and a negativestiffness component; the bearing structure is arranged above the pedestal; the inerter comprises a linear actuating part, a rotating part, a transmission mechanism and a flywheel, wherein the transmission mechanism is in transmission connection with the linear actuating part and the rotating part; the linear actuating part extends in the vertical direction; the upper end of the linear actuating part is directly or indirectly connected with the bearing structure; the rotating part is arranged at the lower end of the linear actuating part; the transmission mechanism is used for transforming up-and-down movement of the linear actuating part into horizontal rotation of the rotating part; the flywheel is installed at the rotating part; the upper end of the positive stiffness component is directly or indirectly connected with the bearing structure; the lower end of the positive stiffness component is directly or indirectly connected with the pedestal; the upper end of the negative stiffnesscomponent is directly or indirectly connected with the baring structure; the lower end of the negative stiffness component is directly or indirectly connected with the pedestal, wherein the positive stiffness component and the negative stiffness component are used for bearing the weight of the bearing structure; and the inerter and the negative stiffness perform combined action in order to reducethe inherent frequency of the vibration damping device and optimize the vibration damping effect of the vibration damping device.

The invention discloses a mini-piezoelectric wind energy collector with a flexible support. The mini-piezoelectric wind energy collector comprises a micro-bracket, a piezoelectric composite beam, a flexible support and a base, wherein the piezoelectric composite beam is connected with the base through the flexible support and the micro-bracket; electrodes are respectively arranged on an upper surface and a lower surface of a piezoelectric layer of the piezoelectric composite beam; a dynamic wind load causes the mini-piezoelectric wind energy collector to vibrate; an electric potential difference is generated between the upper surface and the lower surface of the piezoelectric layer; and power supplied to the load or an energy storage device can be realized by using the electric potential difference. The flexible support introduced by the invention is used for reducing the natural frequency of the mini-piezoelectric wind energy collector and ensures that the mini-piezoelectric wind energy collector generates strong vibration at a slower wind speed, therefore, a critical wind speed of the collector in normal use can be effectively reduced.

The invention relates to the field of vibration application and electric power technology, and particularly to a right-angled piezoelectric cantilever beam vibration energy harvester. The right-angled piezoelectric cantilever beam vibration energy harvester comprises a supporting base and a horizontal metal substrate which is mounted on the supporting base. The horizontal metal substrate is provided with a piezoelectric ceramic wafer at the end which is next to the supporting base. A vertical metal substrate is adhered to the other end of the horizontal metal substrate. The horizontal metal substrate is perpendicular with a vertical metal substrate, thereby forming a right-angled cantilever beam structure. The other end of the vertical metal substrate is provided with a mass block. According to the right-angled piezoelectric cantilever beam vibration energy harvester, the right-angled cantilever beam is formed through adding an auxiliary cantilever beam at the end of the horizontal cantilever beam. Through controlling the structural dimensions of the horizontal cantilever beam and the vertical cantilever beam and the mass of the mass block, controlling for an interval between two front stages of modal frequencies is realized, thereby forming a relatively wide operation frequency band and realizing high-efficiency acquisition and conversion for environment vibration energy.

The invention discloses a quasi zero stiffness vibration isolator using multilayer squeezing type magnetic spring and oscillating bars. The vibration isolator comprises a main shaft, guiding shafts, the oscillating bars and a multiplayer structure; the multilayer structure comprises an upper roof arranged from top to bottom in sequence, an upper end cover, a negative stiffness unit, a lower end cover, positive stiffness unit and a bottom plate; the main shaft is a center shaft with multilayer structure; the guiding shafts and the oscillating bars are multiple, and are all arranged around the main shaft at fixing intervals; the structure is compact, and has more bearing ability under relatively small size. In addition, the negative stiffness unit and the positive stiffness unit are connected in parallel by the vibration isolator using the principle of magnetic negative stiffness; the vibration isolator has the characteristics of high static stiffness and low dynamic stiffness, the inherent frequency of the vibration isolator can be efficiently reduced, the vibration isolation frequency band is widened, and the vibration isolator is suitable for low frequency vibration isolation; thenegative stiffness unit is in the form of multilayer squeezing type magnetic spring, the stronger magnetic induction intensity can be produced, the negative stiffness of magnetic spring is increased,the negative stiffness unit is suitable for high loading occasion, and a wide range of applications is met.

A FRP reinforced rubber vibration isolator and manufacturing method thereof, relate to a vibration isolator and a manufacturing method thereof. The vibration isolator is formed by a rubber layer and a FRP plate with adhesive layers arranged on the upper and lower surfaces which are staggeredly superposed, vulcanized and bonded, wherein the FRP plate is made of fiber reinforced materials and a resin substrate, the fiber reinforced material is one or more of glass fiber, high-strength glass fiber, carbon fiber, aramid fiber, basalt fiber or polyester fiber, the resin substrate is one of the epoxy resin, unsaturated polyester resin, phenolic resin or vinyl ester resin, the FRP plate is formed by superposing 1 to 50 single layer plate which have different principal directions. The manufacturing method comprises preparing FRP plate, arranging adhesive layer, superposing, vulcanization molding. The vibration isolator has higher bearing capacity and excellent damping performance, durability, corrosion resistance, and has simple and applicable manufacturing method.

The invention belongs to the overall blade disk technology of turbines and relates to an adjustment structure and method for the inherent frequencies of blades of the overall blade disk of a turbine. Firstly, the initial inherent frequencies of the blades of the overall blade disk of the turbine are measured; then, according to the measured frequencies, the excitation frequency of periodic pulsation of airflow or the result of dynamic stress measurement is combined and the blade frequency needing to be adjusted is calculated, so that the inherent frequency of each stage of the blades can have safe resonance frequency margin; then, according to the blade frequency needing to be adjusted, the space between every two blades of the overall blade disk is slotted, and the radial depth of each slot is determined according to the requirements of adjusting the frequency; a stop hole is formed in each slot bottom, and a pin is mounted in each stop hole. The structure and the method effectively reduce the inherent frequencies of the blades and change the stiffness, modes of vibration and vibration stress distribution of the blades, and the blades do not resonate or the important mode of vibration of resonance of the blades is tuned out the range of working speed. The structure and the method are simple and easy to operate and significant in frequency modulation effect, are easy to control size precision, and can meet actual requirements.

The invention relates to a low-frequency two-degree-of-freedom horizontal vibration isolation mechanism which comprises three parts, namely an upper support plate, a rigid ball and a lower support plate, wherein the upper support plate is provided with an upper support plate arc; the lower support plate is provided with a lower support plate arc; the rigid ball is positioned between the upper support plate arc and the lower support plate arc; the upper support plate arc is in point contact with the rigid ball; and the lower support plate arc is in the point contact with the rigid ball. When the lower support plate generates displacement in a horizontal direction by being subjected to external force from a substrate, the rigid ball can take pure rolling relative to the lower support plate arc so that the upper support plate arc takes the pure rolling relative to the rigid ball, the integral mechanism can generate displacement relative to an original balance position, and the integral mechanism can be reset to the original balance position under the action of the gravity of the mechanism and loads. The low-frequency two-degree-of-freedom horizontal vibration isolation mechanism disclosed by the invention has the characteristics of simple and compact structure, high space utilization ratio, irrelevance of inherent frequency and the loads, and the like.