CN103794842A - Annular truss-type large space foldable mechanism - Google Patents

Abstract

The present invention provides a ring-shaped truss-type large-scale space expandable mechanism, which is composed of several identical 6R mechanism expandable units connected end to end to form a ring; wherein, the 6R mechanism expandable units are symmetrical up and down and left and right, which include: two identical The two support rods are arranged in parallel longitudinally; four identical chords, including two upper chords and two lower chords; the starting ends of the two upper chords are respectively connected to the upper ends of the two support rods ; The ends of the two upper chords are connected to each other through a rotating pair; the beginnings of the two lower chords are respectively connected to the lower ends of the two support rods through a rotating pair; the ends of the two lower chords are connected to each other through a rotating pair; wherein, each chord Both are movably connected to the adjacent support rod through the slider crank mechanism, and the slider is sleeved on the support rod; one end of the crank is connected to the chord rod through a rotating pair, and the other end is connected to the slider through a rotating pair; the length of the supporting rod is greater than Twice the length of the chord. The ring-shaped truss type large space expandable mechanism of the present invention has a high folding ratio.

Description

A ring truss type large space expandable mechanism

technical field

The invention belongs to the technical field of aerospace equipment and equipment, and relates to an annular truss-type single-degree-of-freedom mechanism, which can be used for satellite parabolic antennas and large space reflector support trusses.

Background technique

With the rapid development of satellite communication, deep space exploration, and earth observation technology, the application requirements for aerospace agencies have become more and more urgent. The size of the actually required spaceflight mechanism is getting bigger and bigger, and the precision is getting higher and higher. However, due to the limitation of the carrying space of the space vehicle, it is required that the spaceflight mechanism must be folded and folded in the fairing during the launch stage. After entering the orbit, it will be deployed to the working state by its own power source. The space expandable mechanism has the function of repeatable expansion and retraction, so it has broad application prospects and important research value. This type of mechanism is widely used in space stations, communication satellite platforms, space telescopes, space shuttles, planetary probes and other spacecraft, such as the 60m foldable radar support arm used for three-dimensional terrain observation in the United States, and the main solar wing support keel of the International Space Station. , The tetrahedron frame antenna on the Russian "Soyuz" spacecraft, the 13m aperture frame antenna on the Japanese ETS-8 satellite, etc.

Chinese patent application 201110057519.X discloses a large-scale space-assembled antenna reflector module unit and its assembly method. The module unit includes a hexagonal expandable truss, a reflective rope net and a rope connection device; the hexagonal expandable truss includes Top hinge, synchronous power hinge, hoop rod, middle oblique rod; two hoop rods of the same length form a synchronous folding rod through a synchronous power hinge, and a synchronous folding rod is connected with two middle oblique rods through two top hinges A plane diagonal structural unit, 12 plane diagonal structural units are connected to each other through a common middle slant bar and a top hinge to form a ring shape, which is to form an antenna reflector module unit and a frame. When connecting, two adjacent diagonal structural units The synchronous folding rods are staggered in space to form two layers of hexagons with different sizes and staggered apex positions in space; the reflective rope net includes a metal net for reflecting electromagnetic waves and an adjustment rope for adjusting the shape of the metal net. The metal net is sewn on On the adjustment rope, the adjustment rope and the above-mentioned module unit truss are fixed through the top hinge, and the connecting rope device is mainly used to connect and fix the reflective rope net and the hexagonal expandable truss.

Chinese patent 03117075.7 discloses a high-rigidity synchronous unfolding and folding space extension arm, which is composed of a repeatable and expandable expandable and folding truss unit, a drive system, a power supply system and a supporting space platform. The expandable and folding truss unit is the most The basic units can be connected through standard delta joints. The driving system is located in the triangular space at the bottom of the extension arm, connected to the supporting space platform, and connected to the power system through the transmission shaft.

The large-scale ring truss antenna with flexible cable net is a relatively mature large-scale mesh-shaped deployment antenna, and its deployment diameter can reach up to 100 meters. attention of the scientific community. The ring truss-type deployment mechanism is the main supporting truss of this type of antenna. It consists of a single polygon or a combination of multiple polygons. The pre-tension is applied by tensioning the connecting cables, so that the reflective surface cable nets arranged on both sides of the ring truss form the required paraboloid. TRW Astro Aerospace in the United States has developed a ring-shaped truss-type expandable mechanism based on parallelogram units based on the characteristics of parallelograms that can be stretched diagonally, and it has been successfully applied to space communication tasks. This solution is simple to unfold and has a single driving source, but due to the presence of multiple sets of bevel gear meshes, the cost of processing and assembly is relatively high, and the folding ratio of this solution needs to be improved. Relevant scientific research institutions in my country have carried out a series of forward-looking research work on spatially expandable mechanisms and achieved certain results, but there is no large-scale and complex spatially expandable mechanism put into application at present.

Contents of the invention

Aiming at the shortcomings of the prior art, the purpose of the present invention is to provide a space expandable mechanism with a high folding ratio.

In order to achieve the above purpose, the present invention provides a ring-shaped truss-type large-scale space expandable mechanism, which is composed of several identical 6R mechanism expandable units connected end to end to form a ring; wherein, the 6R mechanism expandable units are symmetrical up and down and left and right, and their include:

Two identical support rods, the two support rods are longitudinally arranged in parallel;

Four identical chords, including two upper chords and two lower chords; the starting ends of the two upper chords are respectively connected to the upper ends of the two support rods through rotating pairs; the ends of the two upper chords are connected to each other through rotating pairs; The starting ends of the two bottom chords are respectively connected to the lower ends of the two support rods through the rotating pair; the ends of the two bottom chords are connected to each other through the rotating pair;

Among them, each chord is movably connected with the adjacent support rod through the slider crank mechanism, and the slider is sleeved on the support rod; one end of the crank is connected to the chord through a rotating pair, and the other end is connected to the slider through a rotating pair ;

The length of the support rod is more than twice the length of the chord.

In the present invention, the 6R mechanism means that the supporting rod and the chord of the mechanism are connected by 6 revolving pairs.

In the present invention, the four chords can be folded inside the two support rods. Two top chords form a V-bar and two bottom chords form a V-bar.

In the present invention, a plurality of 6R mechanism expandable units with the same parameters can form a ring to construct a large space expandable mechanism. By changing the size of the included angle between the expansion planes where adjacent units are located, a circular or elliptical truss can be constructed to support large-scale spatial expansion antenna metal cable nets with different parameters.

The present invention proposes a circular truss-type large space expandable mechanism based on the expandable unit of the 6R mechanism, which is constructed by connecting the modular units through a double-slider crank mechanism. The mechanism is composed of a planar symmetric 6R mechanism, which is characterized by connecting multiple adjacent 6R expandable units into a ring mechanism with a double-slider crank mechanism and a degree of freedom of movement of 1. The mechanism is realized by driving the rope with a motor or using a built-in torsion spring. of the expansion. Since the freedom of movement of a single 6R mechanism is 3, the present invention uses a rope synchronization mechanism to realize the synchronous movement of the upper and lower V-shaped bars in the 6R mechanism, so that the degree of freedom of the mechanism unit is 1. At the same time, the double-slider crank mechanism is used to realize the linkage between the basic components, so as to realize the synchronous deployment of the large-scale space expandable mechanism. The mechanism has high folding ratio, good unfolding performance and high reliability, and is suitable for the construction of large-scale deployable antennas.

According to another specific embodiment of the present invention, the unfolded state of the expandable unit of the 6R mechanism is: two upper chords and two lower chords are horizontally straightened, perpendicular to the support rods, forming a rectangular truss, and the crank of the slider crank mechanism is a web .

According to another specific embodiment of the present invention, the folded state of the expandable unit of the 6R mechanism is: two upper chords and two lower chords are arranged longitudinally, parallel to the support rods.

According to another specific embodiment of the present invention, two adjacent expandable units of the 6R mechanism share a support rod and a slider on the support rod.

According to another specific embodiment of the present invention, two 6R mechanism expandable units are assembled together through a rope synchronization system to realize the synchronous deployment movement of the two 6R mechanism expandable units.

According to another specific embodiment of the present invention, the synchronous deployment of all the expandable units of the 6R mechanism is realized through the driving of the rope or the torsion spring.

According to another specific embodiment of the present invention, the upper and lower ends of the support rods of the expandable unit of the 6R mechanism have bending parts formed by bending inwards vertically, and the chords are connected to the ends of the bending parts through rotating pairs.

Compared with the prior art, the present invention has the following advantages:

The ring-shaped truss-type large-scale space expandable mechanism of the present invention is composed of a plurality of planar 6R mechanism expandable units. Compared with the parallelogram-shaped basic expandable units, the folding ratio is much improved, and under the same folded volume, it can construct a larger unfolded structure. area ring truss. At the same time, the circular truss-type large-scale space expandable mechanism of the present invention has an overall degree of freedom of movement of 1, which can realize the synchronous deployment movement of multiple units, has higher deployment performance, and is easy to realize single-motor drive. Its interior only includes a moving pair and a rotating pair, which avoids the appearance of synchronous bevel gears and reduces the cost of processing and manufacturing.

Description of drawings

Figure 1 is a schematic diagram of the mechanism of the expandable unit of the 6R mechanism in Example 1;

Figure 2 is the folded state of the expandable mechanism composed of two 6R mechanism expandable units;

Fig. 3 is the unfolding intermediate state of the expandable mechanism composed of two 6R mechanism expandable units;

Figure 4 is the fully expanded state of the expandable mechanism composed of two 6R mechanism expandable units;

Fig. 5 is a schematic diagram of the layout of the synchronous motion rope of the slide block on a support bar;

Fig. 6 is a schematic diagram of the layout of the rope drive mode;

Figure 7 shows the folded state of the ring-shaped truss-type expandable mechanism composed of 12 expandable units of the 6R mechanism;

Fig. 8 is the unfolding intermediate state 1 of the ring-shaped truss type deployable mechanism composed of 12 6R mechanism deployable units;

Fig. 9 is the second unfolding state of the ring-shaped truss type deployable mechanism composed of 12 6R mechanism deployable units;

Figure 10 is the fully expanded state of the ring-shaped truss type expandable mechanism composed of 12 6R mechanism expandable units;

Figure 11 is a schematic diagram of the layout of the torsion spring driving method.

Detailed ways

Example 1

As shown in Figures 7-10, the ring-shaped truss-type large-scale space expandable mechanism of this embodiment consists of several (12) identical 6R mechanism expandable units connected end to end to form a ring.

As shown in Figure 1, the deployable unit of the 6R mechanism is symmetrical up and down and left and right, including:

Two identical support rods 101, 102, the two support rods 101, 102 are longitudinally arranged in parallel; the upper end and the lower end of the support rods have a bending part formed by bending vertically inward, and the chord is connected to the bending part through a rotating pair the end.

Four identical chords, which include two upper chords 201, 202 and two lower chords 301, 302; the starting ends of the two upper chords 201, 202 are respectively connected to the upper ends of the two support rods 101, 102 through the rotating pair; The ends of the two upper chords 201, 202 are connected to each other through the rotation pair; the beginning ends of the two lower chords 301, 302 are respectively connected to the lower ends of the two support rods 101, 102 through the rotation pair; the ends of the two lower chords 301, 302 are connected by Rotating pairs are connected to each other;

Wherein, each chord is movably connected with the adjacent support rod through the slider crank mechanism 4, and the slider 401 is sleeved on the support rod; one end of the crank 402 is connected to the chord through a rotating pair, and the other end is connected through a rotating pair on slider 401;

The length of the support rod is more than twice the length of the chord.

As shown in Figure 2, the folded state of the expandable unit of the 6R mechanism is: two upper chords and two lower chords are arranged longitudinally, parallel to the support rods.

Figure 3 shows the unfolding intermediate state of the deployable mechanism composed of two 6R mechanism deployable units. At this time, the two upper chords form a V-shaped bar, and the two lower chords form a V-shaped bar. In addition, it can be seen from FIG. 3 that two adjacent expandable units of the 6R mechanism share a support rod and a slider on the support rod.

As shown in Figure 4, the unfolded state of the expandable unit of the 6R mechanism is: two upper chords and two lower chords are horizontally straightened and perpendicular to the support rods to form a rectangular truss, and the crank of the slider crank mechanism is a web.

Fig. 5 is a schematic diagram of the arrangement of the synchronous movement ropes of the slider on a support rod. The two sliders 401 on the support bar 101 are connected together by two ropes 502 that go around the pulleys 502 at both ends of the support bar 101 , so that the two sliders 401 can move inward or outward simultaneously. Through the slider synchronization system on the support rod, the degree of freedom of movement of a single deployment unit can be changed to 1, and the stable deployment of the mechanism can be realized.

In this embodiment, the synchronous deployment of all the expandable units of the 6R mechanism is realized through the driving of the rope. Figure 6 is a schematic diagram of the layout of the rope drive method. The rope driving system includes a motor, a driving cable 605, a fixed pulley 601 fixed on the bar, a movable pulley 602 fixed on the slider, a rope displacement compensation spring 603, a slider pressing spring 604 and the like. As shown in Figure 6, the motor drives the driving cable 605 to be tightened in the direction shown in the figure, so that the two sliders on the support rod 101 can move to both ends at the same time, and act on the upper and lower chords through the short connecting rod (crank) , to make it unfold smoothly. Due to the action of the double-slider crank mechanism and the synchronous rope of the sliders, the synchronization of the movement of the rods of each unit of the space expansion mechanism is guaranteed. In the figure, the compression spring 604 of the slide block provides a part of the resistance to drive the unfolding, which avoids the phenomenon of slack in the rope during the unfolding process. The rope displacement compensating spring 603 prevents the sudden increase of the tension of the rope when the mechanism is fully deployed, and plays the role of protecting the motor. After the mechanism is fully deployed and locked, it prevents the rope from being slack and compensates for the displacement of the rope elongation. When the mechanism is fully deployed, the joint between the upper and lower chords is locked, and at the same time, the motor applies a certain tension to the rope, and then locks.

Example 2

The difference between this embodiment and Embodiment 1 lies in: the synchronous deployment of all the expandable units of the 6R mechanism is realized through the drive of the torsion spring. Figure 11 is a schematic diagram of the layout of the torsion spring driving method. As shown in Figure 11, large-torque torsion springs are respectively installed at the rotating joints A, B, C, and D between the chords of the mechanism. superior. The two ropes are staggered as shown in the figure, one end is connected to the displacement compensation spring, and the other end is connected to the motor drive end. When the mechanism is in the folded state, the torsion spring is in the compressed state, and the output torque is the largest. When the mechanism is unlocked, the upper and lower chords start to unfold under the action of the torque of the torsion spring. At the same time, by controlling the release speed of the two release cables, the impact and collision phenomenon caused by the excessive torque of the torsion spring is avoided, and the mechanism is stable and uniform. Expand. When the mechanism is fully deployed and the rotating joints are locked, the release cable is tightened by controlling the motor to increase the internal tension of the mechanism and improve the overall rigidity of the truss.

Although the present invention is disclosed above with preferred embodiments, it is not intended to limit the scope of the present invention. Any person skilled in the art may make some improvements without departing from the scope of the present invention, that is, all equivalent improvements made according to the present invention shall be covered by the scope of the present invention.

Claims (7)

1. A ring-shaped truss-type large-scale space expandable mechanism, which is composed of several identical 6R mechanism expandable units connected end to end to form a ring; wherein, the 6R mechanism expandable units are symmetrical up and down and left and right, including: Two identical support rods, the two support rods are longitudinally arranged in parallel; Four identical chords, which include two upper chords and two lower chords; the starting ends of the two upper chords are respectively connected to the upper ends of the two support rods through rotating pairs; the ends of the two upper chords Connected to each other through a rotating pair; the starting ends of the two lower chords are respectively connected to the lower ends of the two support rods through a rotating pair; the ends of the two lower chords are connected to each other through a rotating pair; Wherein, each of the chords is movably connected to the adjacent support rod through a slider crank mechanism, and the slider is sleeved on the support rod; one end of the crank is connected to the chord through a rotating pair , the other end is connected to the slider through a rotating pair; The length of the support rod is greater than twice the length of the chord. 2. The large-scale space expandable mechanism according to claim 1, wherein the expandable state of the expandable unit of the 6R mechanism is: the two upper chords and the two lower chords are horizontally straightened and perpendicular to the support rods to form a rectangular truss , the crank of the slider crank mechanism is a web rod. 3. The large space expandable mechanism according to claim 1, wherein the folded state of the expandable unit of the 6R mechanism is: two upper chords and two lower chords are arranged longitudinally, parallel to the support rods. 4. The large space expandable mechanism according to claim 1, wherein two adjacent expandable units of the 6R mechanism share a support rod and a slider on the support rod. 5. The large space expandable mechanism according to claim 4, wherein two expandable units of the 6R mechanism are assembled together through a rope synchronization system to realize the synchronous deployment movement of the two expandable units of the 6R mechanism. 6. The large-scale space expandable mechanism according to claim 1, wherein all the expandable units of the 6R mechanism can be deployed synchronously through a rope drive or a torsion spring drive. 7. The large-scale space expandable mechanism according to any one of claims 1-6, wherein the upper and lower ends of the support rods of the expandable unit of the 6R mechanism have bending parts formed by bending vertically inward, and the chord A rod is connected to the end of the bent portion by a swivel joint.

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