CN1827475A

CN1827475A - Mini-sized large-load SMA space synchronous unlocking mechanism

Info

Publication number: CN1827475A
Application number: CN 200610011626
Authority: CN
Inventors: 闫晓军; 张可
Original assignee: Beihang University
Current assignee: Beihang University; Beijing University of Aeronautics and Astronautics
Priority date: 2006-04-10
Filing date: 2006-04-10
Publication date: 2006-09-06
Anticipated expiration: 2026-04-10
Also published as: CN100483291C

Abstract

The invention relates to a micro large load SMA space synchronous unlocking device, which uses the split nut device whose bottoms are connected. Wherein, the upper of split nut contains screw to match the bolt and fixed on upper connector via the bolt; the bottoms of split nut are connected via the base to be fixed on the lower connector; the upper edge of split nut has a positioning ring, which support the split nut for circular limit in normal mounting state to conform the tight match with split nut; the upper end of spring supports positioning ring while lower end is supported by base to be compressed state; one end of SMA wire is connected to the positioning ring while another end is fixed on the base; the spring and the driving element as SMA wire are matched to be utilized; in normal mounting state, the force of spring is higher than SMA wire to straighten the SMA wire while in working, the SMA wire is electrically heated, the force of SMA wire is higher than the force of spring, and the SMA wire will constrict to move the positioning ring downwards to release the limit on split nut, to complete the space unlocking function of said device. The invention can unlock quickly to meet the demand of synchronization, with small volume and light weight.

Description

Mini-sized large-load SMA space synchronous unlocking mechanism

Technical field

The present invention relates to a kind of space unlocking structure, the SMA space synchronous unlocking mechanism of particularly a kind of miniature big load (being 20000N).

Background technology

Spacecraft needs multiple separation release mechanism finish the space unlocking function, for example, and with the space development of large-sized solar windsurfing and other annex on the separating of carrier rocket, the satellite etc.This separation release mechanism mainly contains the effect of two aspects: on the one hand protect capacity weight during launching, prevent to be subjected to the influence of launch load and release; On the other hand,,,, discharge capacity weight rapidly, realize unlocking function at flight track as vibration and pollution damage etc. with minimal deleterious effect specifying constantly.For guaranteeing to connect, spacecraft uses a release mechanism incessantly in some cases, and the synchronism of mechanism's release is to influence the another key factor that link separates.

Along with the appearance of grapefruit satellite of new generation, the inside and outside parts of satellite are pressed close to vibration and source of pollution more, and the therefore low vibration of development, free of contamination space release mechanism become inevitable.In the research of low oscillation space release mechanism, the shape memory characteristic implementation space unlocking function that main focus is applying shape memory alloy SMA.Can be returned to high temperature parent phase shape during the heating of SMA material, the strain of generation about 6% and huge restoring force.Therefore, NASA of NASA and the commercial company that some are famous all have and have carried out the research as the later-model space unlocking structure of mechanical drive element with SMA, Darin Mckinnis wherein, Fastening Apparatus Having Shape Memory AlloyActuator, NASA Johnson Space Center, MSC-21935-1., introduced the space release mechanism of NASA, adopt the SMA rod to make the driver element of release mechanism, its structure as shown in Figure 1, 2, 3, cylindrical fixed cover 14 is fixed on down on the attaching parts 34 by screw thread.Piston 54 is positioned at fixed cover, and its underpart contacts with SMA rod 24, and inside contacts with distinguish nut 72.The distinguish nut is by forming along the nut that circumferentially is divided into three parts, fix by pin 78 and piston, shown in A-A cutaway view among Fig. 2, coupled condition, the boss 68,70 of piston cooperates with the

boss

74,76 of distinguish nut, the each several part closed contact of distinguish nut under the effect of piston, form complete screw thread in inside, packing ring 92 is fixed on the fixed cover, the distinguish nut there is the effect of axial limiting, bolt 26 passes upper connector 36 and is connected with the distinguish nut, realizes being connected and fixed of two parts thus; When separating release, energising heating SMA rod release mechanism, pin is cut off in the elongation of SMA rod, moves on the driven plunger, on the distance of moving just be the width of distinguish nut step, make the boss 68,70 of piston and the

boss

74,76 of distinguish nut throw off, the radial constraint of distinguish nut is removed, and each several part outwards opens, discharge tie bolt, thereby realize the separation release between upper and lower attaching parts.

Though the space release mechanism of NASA can repeated usage, its shortcoming is: (1) need assemble again, complicated operation; (2) the release time longer, can't satisfy the synchronism requirement; (3) connect and carrying in order to guarantee, its volume and quality are all relatively large, are not suitable for the space release of miniature big load.

Summary of the invention

Technology of the present invention is dealt with problems: overcomes the deficiencies in the prior art, provides a kind of release rapid, can satisfy the requirement of synchronism, and little, the lightweight mini-sized large-load SMA space synchronous unlocking mechanism of volume.

Technical solution of the present invention: mini-sized large-load SMA space synchronous unlocking mechanism, its characteristics are: the distinguish nut structure that adopts the bottom to link together, the distinguish nut has screw thread in the top, be connected with bolt, and by being bolted on the upper connector, the bottom of distinguish nut links together and is fixed on down on the attaching parts by base, distinguish nut top steady ring circumferentially arranged, under conventional installing condition, steady ring supports the distinguish nut and circumferentially retrains, guarantee that the distinguish nut fits, steady ring carries out axial location by spring and SMA silk, steady ring is supported in the spring upper end, the lower end is supported in base, make it be in compressive state, SMA silk one end links to each other with steady ring, and the other end is fixed on the base, and spring and the pairing of driver element SMA silk are used, under the usual installing condition, the power of spring makes the SMA silk stretching greater than the SMA silk, when work, energising heating SMA silk, the power of SMA silk is greater than the power of spring, and the SMA silk shrinks the drive steady ring and moves down, and removes the constraint to the distinguish nut, discharge bolt, thereby finish the space unlocking function of mechanism.

The present invention can be returned to high temperature parent phase shape when utilizing the heating of SMA material, and the strain of generation about 6% and huge restoring force are realized mechanism's release; Utilize SMA material at low temperature state yield stress low, the characteristic of condition of high temperature high yield stress cooperates the reusable function of realization mechanism with spring.The yield force of installing condition (low temperature), spring force SMA silk during greater than low temperature, the SMA silk is in tension under the spring force effect, and the spring application steady ring guarantees that the distinguish nut fits.Energising heating (high temperature), the restoring force of SMA silk is greater than spring force at this moment, and the SMA silk shrinks, and drives steady ring and moves down, and compression spring is removed the constraint to the distinguish nut, discharges bolt, thereby finishes the space unlocking function of mechanism.After energising finished, drop in temperature, SMA silk low temperature yield force were less than spring force, and under the effect of spring force, the SMA silk extends, and steady ring returns to initial position, realizes the reusable function of mechanism.

The present invention compared with prior art has more advantages at aspects such as volume, quality, synchronisms, more can satisfy the harsh requirement of aerospace apparatus to volume, quality, is in particular in the following aspects:

(1) bonded assembly distinguish nut structure in bottom has been simplified mechanism design, and is simple in structure, the reliability height;

(2) installation dimension of the present invention is no more than Ф 30mm, and as shown in Figure 7, volume is little, light weight;

(3) the present invention is directly to SMA silk energising heating, and prior art then is an energising heating resistor rod, conducts heat by resistor rod and heats the SMA rod, and both compare, and time of heat required for the present invention is shorter, and release is more rapid;

Show by test that (4) under vdc 28V effect, mechanism separates release in the 0.1s of the present invention, can better satisfy the synchronism requirement of mechanism;

(5) the present invention adopts SMA silk and spring to cooperate the pulling steady ring, can recover original structure automatically, and prior art then needs to ressemble just and can reuse, so ground of the present invention repeated usage is more convenient.

Description of drawings

Fig. 1 is the space release mechanism structural representation of NASA;

Fig. 2 is the A-A cutaway view of Fig. 1;

Fig. 3 is piston and the distinguish nut outside drawing of NASA;

Fig. 4 is a mounting structure scheme drawing of the present invention;

Fig. 5 is an inner structure schematic three dimensional views of the present invention;

Fig. 6 is a bottom of the present invention bonded assembly distinguish nut structure scheme drawing;

Fig. 7 is an installation dimension scheme drawing of the present invention;

Fig. 8 is a SMA silk installation length scheme drawing of the present invention.

The specific embodiment

Shown in Fig. 4,5, the present invention is made up of SMA silk 2, spring 3, distinguish nut 4, bolt 5, steady ring 7, base 8, the present invention is fixed on down on the attaching parts 1 by screw thread, distinguish nut 4 bottoms are connected with base 8 by screw thread, top is circumferentially located by steady ring 7, and fixing by bolt 5 with upper connector 9, finish the connection of adjacent two parts thus.Distinguish nut 4, as shown in Figure 6, by forming along three parts of circumferentially dividing equally distribution, the bottom connects, in swell fixture 6 is arranged, can be by swell fixture 6 adjustment distinguish nuts 4 open sizes.Spring 3 lower ends contact with base 8, and the upper end contacts with steady ring 7, is in compressive state, compresses steady ring 7, guarantee the circumferential location of 7 pairs of distinguish nuts 4 of steady ring, make distinguish nut 4 closed under confined state, as shown in Figure 4.SMA silk 2 upper ends link to each other with steady ring 7, and the lower end is fixed on the base 8, in tension under the effect of spring force.When energising heating SMA silk 2 is realized unlocking functions, consider the Insulation Problems of SMA silk 2, steady ring 7 be an insulating material, the mode that is connected employing insulating material mechanical stop of SMA silk 2 and base 8.

Adopt the NiTi alloy silk that contains Ti amount 50%, diameter 0.5mm in the SMA alloy system as mechanism's unlock drive element when designing in the embodiment of the invention, during the energising heating, the start distance of SMA silk 2 is main relevant with two factors: the original length of silk and silk plasticity pre-tension deformation amount at low temperatures.SMA silk 2 original lengths are long more, plasticity pre-tension deformation amount is big more, and the distance that the alloy silk shrinks during heating is also big more.Take all factors into consideration the dimensional characteristic and required SMA silk 2 contract by distance of release of mechanism design, calculate to determine that the pre-tension deformation amount is that effective installation length of 8% SMA silk is 50mm, as shown in Figure 8.

The design of spring 3 need be satisfied 2 requirements: under (1) low temperature is installing condition, the yield force of SMA silk when spring force is greater than low temperature guarantees that energising end back SMA silk can be returned to the shape (realizing the reusable function of mechanism) of low-temperature deformation under the effect of spring force; (2) i.e. energising heating under the high temperature, the restoring force of SMA silk 2 when spring force is less than high temperature, SMA silk 2 could shrink (unlocking function of realizing mechanism) by against the force of the spring like this.The low temperature yield force and the high-temperature reply power of SMA silk is determined in test, determines spring rate k=20N/mm by calculating, and the precompressed compression of installing condition lower spring 3 is 200N.

Working process of the present invention: under the installing condition, the position of steady ring 7 as shown in Figure 4, when control system was sent unlock command, energising SMA silk 2 shrank, and steady ring 7 moves down thereupon, compression spring 3, removed the circumferential constraint of distinguish nut 4, distinguish nut 4 is along circumferentially unclamping the constraint release of bolt 5, adjacent two parts releases separate, and finish the design function of mechanism.Energising is moving on the steady ring 7 under the spring force effect of spring 3 after finishing, and SMA silk 2 returns to the length under the confined state, recovers original structure, thereby can connect and release next time.

Claims

1, mini-sized large-load SMA space synchronous unlocking mechanism, it is characterized in that: the distinguish nut structure that adopts the bottom to link together, distinguish nut (4) has screw thread in the top, be connected with bolt (5), and be fixed on the upper connector (9) by bolt (5), the bottom of distinguish nut (4) links together and is fixed on down on the attaching parts (1) by base (8), distinguish nut (4) top steady ring (7) circumferentially arranged, under conventional installing condition, steady ring (7) supports distinguish nut (4) and circumferentially retrains, guarantee that distinguish nut (4) fits, steady ring (7) relies on spring (3) and SMA silk (2) to carry out axial location, steady ring (7) is supported in spring (3) upper end, the lower end is supported in base (8), make it be in compressive state, SMA silk (2) one ends link to each other with steady ring (7), the other end is fixed on the base (8), spring (3) and driver element SMA silk (2) pairing are used, under the usual installing condition, the power of spring (3) is greater than SMA silk (2), make SMA silk (2) stretching, when work, energising heating SMA silk (2), the power of SMA silk (2) is greater than the power of spring (3), and SMA silk (2) shrinks drive steady ring (7) and moves down, and removes the constraint to distinguish nut (4), discharge bolt (5), thereby finish the space unlocking function of mechanism.

2, mini-sized large-load SMA space synchronous unlocking mechanism according to claim 1 is characterized in that: described steady ring (7) is an insulating material.

3, mini-sized large-load SMA space synchronous unlocking mechanism according to claim 1 is characterized in that: described SMA silk (2) and base (8) be connected the mode that adopts the insulating material mechanical stop.

4, mini-sized large-load SMA space synchronous unlocking mechanism according to claim 1 is characterized in that: swell fixture (6) is arranged, by the open size of distinguish nut (4) under expansion spiral shell (6) the nail adjusting work state in the described distinguish nut (4).