138results about How to "Avoid secondary impact" patented technology

The invention discloses an inertial frequency-modulation drive rotating speed protection control system and method for a doubly-fed wind turbine. A wind speed detection module collects the wind speed, the rotating speed of a fan and the pitch angle parameter. According to a rotating speed protection control link, the real-time captured mechanical wind power of the fan is computed according to information collected by the wind speed detection module, and a loss computing module is connected with the rotating speed protection control link, the loss is subtracted from the real-time captured mechanical wind power; and the obtained computing result is compared with electromagnetic power output by a generator, an input and output power difference caused when the doubly-fed wind turbine participates in system frequency modulation is obtained, the input and output power difference is transmitted to a proportional link and an integration link through a trigger switch, the negative feedback power control quantity is output after the proportional link and the integration link act, and the negative feedback control quantity and an inertial frequency-modulation control signal jointly serve as a frequency modulation additional active power given value. By means of the inertial frequency-modulation drive rotating speed protection control system and method, secondary impact on the system frequency when the doubly-fed wind turbine exits from the frequency modulation can be avoided, and the problem that the power loss is large due to that fact that the rotating speed in the constant rotating speed region is overly lowered is solved.

The invention discloses an ultra-high voltage transmission line self-adaptive three-phase recloser judging method with a shunt reactor. The line residual voltage mode component amplitude is taken as criterion and the failure property can be exactly judged before the circuit breakers at two sides of the transmission line are reclosed, thus respectively realizing the quick action of the recloser during the transient failure and the locking of the recloser during the permanent failure. Compared with the prior art, the judging method of the invention avoids the secondary impact on the electric installation and the threatening on the stability of the system caused by that the circuit breaker is reclosed at the permanent failure in three-phase, quickens the closing time during the transient failure, is beneficial for the stability of the system and the continuity of the power supply, can only use a micro-computer protection device to process the sampling data of the voltage at the line termination without adding any devices, affects no action time of the protection and has simple arithmetic.

A percussion mechanism (21; 41) for a percussion power tool includes an impact element (24; 44) reciprocating along a percussion axis (22; 42) of the percussion mechanism (21; 41) and acting on the striker (26, 46). The contact point (27, 47) and counter-contact point (28, 48) are provided between the striker (26, 46) and the impact element (24, 44), with the contact point (27, 47) being formed as an exposed contact point and being arranged outside of the percussion axis (22; 42).

A spring is formed of a relatively thin sheet of spring material, which is constricted and held in place at each end forming a bell curve being located between two substantially planar members. As additional compressive force is applied in the vertical direction, the curve then compresses and starts to form sine waves. In an improved embodiment of the present invention, the sine wave spring is formed in a wedge shape, so that it is gradually taller and more progressive. This embodiment has been tested for use as a trailer spring with positive results. This wedge-shaped sine wave spring provides even more advantages over the Prior Art. The wedge-shaped prototype illustrates also how the present invention may be expanded to other shapes, in order to alter the spring characteristics, and also for packaging and other concerns.

The invention relates to a method for recognizing circuit switching on to a failure through a specific short window integral value of directional traveling waves, and belongs to the technical field of electrical power system relay protection. When the single-phase earth failure occurs on an electric transmission line, single-phase reclosing is adopted, the switching-on line mode current traveling waves obtained by a measuring end and switching-on line mode voltage traveling waves are used for forming forward direction current traveling waves and reverse current traveling waves, the absolute value of the forward direction current traveling waves and the absolute value of the reverse current traveling waves are solved, the integral value ration of the forward current traveling waves and the reverse current traveling waves in a window in 2 tao min to 4 tao min after switching on is carried out is calculated to build switching on to failure recognizing criteria. If the integral value ratio is smaller than the set threshold value k, the line is judged to be a switching on to non-failure line, and if the integral value ratio is larger than k, switching on to failures is judged. The simulation verifies and shows that the method is not affected by failure positions, transition resistance and initial failure phase angles, the situation of the switching on to failure line can be reliably recognized, and the line is prevented from being impacted again.

A shock isolation system for electronic devices includes a first baseboard, a second baseboard and a plurality of helical springs interposed transversely between the first baseboard and the second baseboard. The helical springs can deform horizontally and vertically to isolate horizontal and vertical vibration-impact on the electronic devices. The first baseboard and the second baseboard further are bridged by a plurality of damping elements, which have damping characteristics to dissipate kinetic energy and reduce the vibration amplitude and instantaneous acceleration between the first baseboard and the second baseboard, thereby to enhancing the composite effect. The first baseboard further has a plurality of buffer struts to separate the first baseboard and the second baseboard, and prevent the second baseboard from directly hitting the first baseboard.

The invention discloses a target object lateral impact test device, which comprises a frame, an impact hammer, an impact hammer height measuring part, an impact hammer height adjusting part, an impact hammer speed measuring part, a secondary impact preventing part and a display screen; the impact hammer The height measuring part is composed of a displacement sensor arranged on the frame; the height adjustment part of the impact hammer includes a telescopic connecting rod and an electric push rod, and the rear end of the impact hammer is fixed on the other end of the telescopic connecting rod; There is an electromagnetic relay, one end of the electric push rod is hinged to the frame, and the other end is connected to the electromagnetic relay; the impact hammer speed measurement components include a photoelectric door and a light baffle, the photoelectric door is set on a lifting rod, and the light baffle is fixed on the impact hammer; Secondary impact prevention components include rotating shafts, brake discs, brake calipers, brake lines and controllers. The invention can provide relatively large impulse, can effectively avoid secondary impact, is convenient to use, and has low cost, and can be used for lateral impact tests of various targets.

The invention discloses a large-size drop hammer impact device which is used for testing properties of metals, nonmetals and composite materials. The large-size drop hammer impact device comprises a pile foundation, a holding platform, a rigid platform, a lattice rigid bracket, a high-precision guide track, a drop hammer, a counter weight, a springback prevention secondary hitting system, an excitation device, a rigid wall, a butterfly spring and a jack. The drop hammer comprises two parts, namely a hammer body and a hammer head; a sensor is mounted between the hammer body and the hammer head,the weight of the drop hammer can be freely increased and decreased according to situations, and then testing requirements of different impact masses can be met; the springback prevention secondary hitting system above the counter weight can be immediately locked after a test part is hit for a first time, then secondary hitting can be prevented, and testing precision can be ensured; the excitation device is arranged on the lattice rigid bracket, the excitation device is an ejector and can provide a primary speed for the hammer head in testing, then the impact speed of the drop hammer can be increased, and a high-speed hitting testing requirement can be met. By adopting the large-size drop hammer impact device, both low-speed low-mass hitting testing and high-speed high-mass hitting testing can be met.

The invention discloses a power distribution network permanent fault identification method based on an injected signal. An intelligent load switch provided with an FTU is adopted to take the place of a sectionalizer, and a topological structure of a whole feeder keeps complete and can not be divided into multiple sections after an interphase short-circuit fault and three-phase trip happen on the feeder. Under the background, the power distribution network permanent fault identification method based on the injected signal is disclosed. The method includes the steps that a constant-frequency voltage detection signal is injected between faulty phases after the trip fault of the feeder, an equivalent input impedance of a faulty interphase port is calculated by means of detected voltage and current of the injected signal, and the equivalent input impedance is compared with an equivalent input impedance obtained before the fault and based on a power frequency signal at normalized frequency; amplitudes of the impedances are proximately equal during an instantaneous interphase fault; the amplitudes of the impedances are much different during a permanent fault, a permanent short-circuit fault is identified, and self-adaptation reclosing is further achieved. By means of the scheme, secondary short-circuit current rush caused due to the fact that reclosing is carried out during the permanent fault can be effectively avoided, and power supply of a faulty line can be quickly and conveniently restored.

The invention relates to a positive current traveling-wave principle component cluster analysis-based closing fault identification method, and belongs to the technical field of power system relay protection. According to the method, after a power transmission line is in a single-phase-to-ground fault, by a single-phase recloser, a positive current traveling-wave is constructed by line-mode current and line-mode voltage travelling waves which are obtained by a measurement end; principle component cluster analysis is carried out by absolute value data of the positive current traveling-wave within a fixed time window after closing; identification is carried out according to a projection value of sample data in a principle component analysis cluster space; if the projection value q1 is greater than a threshold value q1,set, a closing fault is judged; and if the projection value is less than or equal to q1,set, the condition that the circuit is free of a fault is judged. Simulation verification shows that the condition of a closing fault circuit can be reliably identified, and secondary impact to the circuit is avoided.

The invention discloses an energy-absorbing guide anti-collision device for a pier. The anti-collision device comprises a tubular pile group arranged beside the pier, wherein, an anti-collision buoyancy tank is sheathed outside the tubular pile group. The energy-absorbing guide anti-collision device for the pier has the advantages of simple structure, low cost and capability of absorbing energy during the collision process and guiding ship motion.

A shock test device comprises a test board, a stand column, a support plate, a shock sleeve and a shock hammer. The stand column is fixed on the test board, the support plate is fixedly connected with the stand column, an interval is formed between the support plate and the test board, the shock sleeve is fixed on the support plate, an intercepting hole is formed in the side wall of the shock sleeve, the shock hammer can drop on the test board through the intercepting hole, a solenoid valve is arranged on the outer side of the shock sleeve, and the valve core of the solenoid valve can stretch into the intercepting hole to clamp the shock hammer. The shock test device controls the connection and disconnection of the solenoid in shock process to enable the valve core of the solenoid valve to stretch into the shock sleeve through the intercepting hole on the side of the shock sleeve, and to stop the shock hammer which shocks from rebounding and falling down again, and thus a secondary shock to a testing part caused by rebound of the shock hammer is avoided. The invention further provides a shock test method.

The invention relates to a liquid gas type shock absorber, which consists of an upper connector, a spline external cylinder, a cylinder sleeve, a mandrel, a piston, a falling protection connector and a lower connector. The shock absorber is basically characterized in that the upper connector is connected with the spline external cylinder through a spline; the external cylinder of the shock absorber consists of the spline external cylinder and the cylinder sleeve; the mandrel and the piston are arranged inside the cylinder sleeve and are connected with the upper connector through thread; and the falling protection connector is connected with the cylinder sleeve and the lower connector through thread. According to the characteristic that the volume of gas changes along with the change of the temperature and pressure, the shock absorber adopts gas as an elastic element and has better shock absorbing performance. Simultaneously, liquid is taken as a pressure transfer element, thereby not only improving the stability of the shock absorbing system, but also carrying out the liquid sealing of the gas and consequently improving the tightness of the cylinder. The shock absorber has the advantages of wide application range, good flexibility, low impact, good stability, and the like.

The invention discloses an impact energy absorption mechanism. The impact energy absorption mechanism comprises an impacted part and an opposite part opposite to the impacted part in position, wherein at least one martensite initial phase shape memory alloy beam is supported between the impacted part and the opposite part, and a displacement restrictor can be further arranged between the impacted part and the opposite part. With the technical scheme, the impact energy absorption mechanism not only prevents the appearance of the secondary impact problem in an impact energy absorption process, but also can completely recover deformation of the shape memory alloy beam through a temperature rise; therefore, reusability of the mechanism is achieved.

The invention, which relates to the technical field of mechanical property testing, provides a multi-point multi-directional drop hammer impact device and a test method. The multi-point multi-directional drop hammer impact device comprises a curvature impact table, anti-collision columns, supporting side plates, a cross beam, guiding sliding blocks, impact guiding tubes and a drop hammer. The cross beam is arranged above the supporting side plates. The anti-collision columns are arranged on the curvature impact table. The guiding sliding blocks are arranged on the cross beam and can slide along the cross beam; and the upper ends of the impact guiding tubes are connected with the guiding sliding blocks. The anti-collision columns include column bodies, capturing rods, and springs; two capturing rods are fixed at the end surface of each column body; and springs are arranged between the capturing rods. When the device is used for testing, the impact energy and direction can be adjusted based on needs, an impact point can be set accurately, and multiple drop hammers can be released to simulate multi-point impact loads. Therefore, technical problems of fixed impact point, single impactangle, and secondary hamper dropping in the deep roadway similar material simulation testing are solved. The device has advantages of great convenient in operation and precise controlling and the like.

The invention provides a method and a safety device for protecting a pedestrian by an automobile at the time of colliding of the pedestrian and the automobile. In the invention, the safety device is arranged on the rear part of a front cover of the automobile, and protects the pedestrian from secondary injury caused by the front cover or a front windshield after the pedestrian is hurt by a bumper when the automobile and the pedestrian collide; an air bag is arranged behind the front cover of the automobile so as to unfold the air bag to play a role in protecting the pedestrian to reduce injury to the pedestrian when the collision happens; the rear side of the front cover rises upwards by other additional measures when the air bag is unfolded, and the pedestrian can fall off towards the outside of the automobile after impact force received by the pedestrian is absorbed by the air bag and the front cover of the automobile so as to protect the pedestrian from the secondary collision. The method and the device can particularly protect the head of the pedestrian from injury.

The invention provides a photovoltaic assembly impact testing machine which comprises a testing rack, a swing ball and a swing string, wherein the testing rack is used for placing and fixing a photovoltaic assembly sample, and the swing string slings the swing ball. The swing ball is connected with a first controller through a cord, and the first controller includes a first motor which is used for pulling the swing ball to stop the swing ball from continuing swinging. The testing rack is provided with a pressure sensor. The pressure sensor and the first motor are connected with a same processor used for receiving data of the pressure sensor and controlling the work of the first motor. According to the photovoltaic assembly impact testing machine, the pressure sensor is arranged on the testing rack, the pressure sensor transmits data of received impact to the processor when the photovoltaic assembly sample is impacted by the swing ball for the first time, the processor then reacts and causes the motor connected to the swing ball to quickly run, and the motor quickly pulls the swing ball to stop the swing ball from continuing swinging, thereby preventing the photovoltaic assembly sample from being impacted by the swing ball for the second time and guaranteeing that testing data obtained by a tester can accurately and truly reflect the anti-collision capability of the photovoltaic assembly sample.

Provided is a hydraulic buffering device using shape memory alloy. Power consumption and reset are carried out through single-shaft stretching of a pseudo-elastic shape memory alloy pull rod. The function of amplifying displacement is achieved through the area ratio of a large piston and a small piston in a hydraulic device. When the shape memory alloy pull rod deforms a little, namely the large piston moves a little relative to a hydraulic cylinder, a small plunger connected with the outside moves a long distance relative to the hydraulic cylinder, and the function of buffering impact of the outside is achieved. On one hand, the buffering stroke is large; on the other hand, the shape memory alloy pull rod is simple and uniform in stress state, high in phase change utilization rate and large in energy consumption. Action force during buffering is stable, and the buffering device can be reset timely, repeatedly used continuously and suitable for buffering protection of important military and civil devices.

The invention belongs to automotive transmissions and particularly relates to a synchronizer structure capable of preventing a secondary impact during gear shift. The synchronizer structure is composed of a tooth holder, a synchronizing ring, a spring, a sliding block, a tooth sleeve, joint teeth and a gear, wherein the tooth holder is fixedly connected onto a transmission shaft through an internal spline, the tooth sleeve is installed on the tooth holder and capable of freely sliding on the tooth holder left and right, the sliding block is arranged between the tooth holder and the tooth sleeve and capable of moving axially under the drive of the tooth sleeve, and the joint teeth rotate along with the gear. The synchronizer structure is characterized in that the tooth sleeve is provided with a locking tooth, the locking tooth contacts with a corresponding synchronizing ring locking tooth and is locked, the tooth sleeve is further provided with an alignment tooth, the chamfered angle of the alignment is smaller than that of the locking tooth, the axial dimension is long and thin, and a notch is arranged at a position corresponding to the synchronizing ring. According to the synchronizer structure, the structure is reasonable, the gear shift is stable, a driver feels comfortable during gear shift, and the secondary impact during gear shift is prevented effectively.

The invention belongs to the wind power generation technology field, especially relates to a wind farm single circuit outgoing line self-adaptive three-phase reclosing strategy. According to the strategy, after the tripping of the three phases of the wind farm single circuit outgoing line, time of maintaining the transient stability of the wind farm is prolonged; and at the same time, the fault property of the outgoing line is determined: when the fault is transient, and disappears, a circuit is reclosed by a reclosing motion; when the fault is permanent, a recloser is locked, and the line is not superposed. Under a precondition of prolonging the transient stablility time of the wind farm, the rapid determining of the fault property of the outgoing line of the wind farm is realized, and superposition success rate after the tripping of the three phases of the wind farm outgoing line is effectively improved, and therefore second impact on a system caused by the superposition with the permanent fault and the existing transient fault is prevented.

The invention relates to an impact excitation system and a test system based on the impact excitation system. An impact rod is mounted in an impact box and controlled by an electromagnet; a rebound spring in the impact box ensures that the impact rod does not have a secondary impact with a blade to be tested; a blade fixture system is firmly connected with a base through a blade supporting seat soas to reduce noise caused by vibration of the system; the overall position of the excitation system is controlled by a magnetic square box; and an impact depression angle/elevation angle of the impact rod is adjusted through a position adjusting bracket. The invention effectively removes the noise generated by the secondary impact in the prior blade vibration measurement experiment, so that the experimental results of the vibration measurement system are more accurate. The impact excitation system can also be used as a mechanical vibration excitation source for vibration measurement systems for components other than the blade.

The invention discloses a shock test device which is characterized in that an insertion hole is formed in the side wall at one end of a sleeve, a supporting piece is fixed on the outer side wall of the sleeve, one end of a pulling rod can extend into the insertion hole, the middle of the pulling rod is movably connected with the supporting piece, a driving piece is fixedly connected with the other end of the pulling rod, and a shock hammer can enter the sleeve from one end, away from the insertion hole, of the sleeve and fall down from the other end of the sleeve. A photoelectric inductive assembly is arranged at one end, close to the insertion hole, of the sleeve. A control module is electrically connected with the driving piece and the photoelectric inductive assembly. When the shock hammer falls down from the sleeve, the photoelectric inductive assembly is triggered to generate an inductive signal on the control module. When the shock hammer rebounds again to enter the sleeve, the control module controls the driving piece to work, the driving piece drives the pulling rod to move relative to the supporting piece, and one end of the pulling rod extends into the insertion hole to intercept the shock hammer. The shock test device can protect the shock hammer against secondary shock. The invention further provides a shock test method.