Folding and unfolding joint for antenna

Abstract

The invention relates to a folding and unfolding joint for an antenna, and belongs to the technical field of antennas. The device comprises a middle support and two connecting seats, wherein the two ends of the middle support are connected with the corresponding connecting seats through bearings; each connecting seat is provided with an upper group of spring connectors and a lower group of spring connectors, the two opposite upper groups of spring connectors are connected through SMA springs a, the two opposite lower groups of spring connectors are connected through SMA springs b, and the SMA springs a and the SMA springs b are located above and below the middle support respectively. The log-periodic antenna can be folded and unfolded by adopting a novel shape memory alloy material, so that the log-periodic antenna is smaller and more portable.

Description

Technical Field

[0001] The present invention relates to the field of antenna technology, and in particular to a retraction and extension joint for an antenna. Background Art

[0002] At present, logarithmic periodic antennas are often used in a new reconnaissance and early warning method of vehicle + multi-rotor UAV. The ground mobile vehicle arrives at the designated location, the antenna is fixed on the multi-rotor UAV, the multi-rotor UAV carries the antenna into the air, and the antenna is connected to the communication terminal of the ground vehicle through a cable for direct signal transmission. When the multi-rotor UAV reaches a suitable height, the antenna starts working.

[0003] However, the traditional log-periodic antenna in the same frequency band has certain defects: when the operating frequency of the antenna is 27-110Hz, the length of the antenna is about 5 meters, the weight is heavy, and the energy consumption is high; and the folding action of the commonly used log-periodic antenna is mainly achieved by motors, which is not convenient for drones to carry. Summary of the invention

[0004] The purpose of the present invention is to provide a retractable joint for an antenna in view of the defects and shortcomings of the prior art. The retractable joint adopts a new shape memory alloy material to make the log-periodic antenna more compact and portable.

[0005] The present invention is achieved through the following technical solutions:

[0006] A retractable and extendable joint for an antenna comprises an intermediate support and two connecting seats, wherein both ends of the intermediate support are connected to the corresponding connecting seats via bearings; each connecting seat is provided with an upper and a lower set of spring connecting heads, wherein the two upper sets of spring connecting heads facing each other are connected via SMA springs a, and the two lower sets of spring connecting heads facing each other are connected via SMA springs b, and the SMA springs a and the SMA springs b are respectively located above and below the intermediate support.

[0007] Furthermore, the extension directions of the SMA spring a and the SMA spring b are parallel to each other, and two of each are provided.

[0008] Furthermore, one end of the spring connector is connected to the SMA spring, and the other end is hinged to the connecting seat where the spring connector is located.

[0009] Furthermore, two micro electromagnetic locks are arranged in the middle support; a locking hole is arranged on the support platform of the connecting seat; the micro electromagnetic lock faces the support platform on its outside; in the locked state, the lock core of the micro electromagnetic lock passes through the outer wall of the middle support and is located in the corresponding locking hole.

[0010] Furthermore, a support platform is provided on the inner side of the connecting seat; the extended connecting end of the intermediate support and the support platform are respectively located on both sides of the bearing and realize connection with the bearing.

[0011] Furthermore, the intermediate support includes a support body and a support cover; the support cover is buckled on the support body to form a closed space; the micro electromagnetic locks are all located in the closed space; the outer side of the support body is provided with an extended connection end designed integrally with the support body;

[0012] The bearings are provided on both sides of each support platform, and there are four bearings in total;

[0013] The outer sides of the bearings on both sides of the support platform are the ends of the support cover plate and the extended connection ends respectively.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] This device uses a new shape memory alloy material for retractable key design to achieve the design and manufacture of an ultra-light new retractable log-periodic antenna structure, which can be 1 to 2 orders of magnitude lighter than the current retractable log-periodic antenna in the same frequency band. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is an overall structural diagram of an embodiment of the present invention;

[0017] Figure 2 yes Figure 1 Schematic diagram of the structure of the cover plate without support;

[0018] Figure 3 is a structural diagram of joint unlocking during the folding process of the antenna according to an embodiment of the present invention;

[0019] Figure 4 is a diagram of the joint structure of the antenna in the folded state according to an embodiment of the present invention;

[0020] Figure 5 is a diagram of a joint structure during an antenna deployment process according to an embodiment of the present invention;

[0021] Figure 6 is a diagram of a joint locking mechanism during an antenna deployment process according to an embodiment of the present invention;

[0022] Figure 7 It is a structural explosion diagram of an embodiment of the present invention.

[0023] Figure 8 The matching structure diagram of the support seat and the bearing in the embodiment of the present invention is shown in FIG.

[0024] Fig. 9 Schematic diagram of the antagonistic interaction principle of two SMA elements.

[0025] In the figure: 27-1, support cover plate, 27-2, connecting seat, 27-3, spring connector, 27-4, SMA spring a, 27-5, SMA spring b, 27-6, micro electromagnetic lock, 27-7, bearing, 27-8, support body, 27-9, extended connecting end, 27-10, locking hole. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0027] The present invention takes creeping invertebrate reptiles as bionic objects, and uses the Ω-shaped motion form of the reptiles during crawling, thereby utilizing the design concepts of morphological and functional bionics to propose a bionic mechanism conceptual configuration, avoiding a large number of servo mechanisms in traditional mechanisms, and is very suitable for miniaturized environments.

[0028] Antagonistic (inter-driving) SMA actuators, that is, there are two groups of SMA actuators that work against each other. The basic principle can be described as driving the first group of SMA actuators, which undergo austenite transformation, and the second group of SMA actuators at room temperature will passively undergo martensite non-twin transformation. During the cooling process, the first group of SMA actuators undergo martensite transformation, and then drive the second group of SMA actuators, then the second group of SMA actuators undergo austenite transformation, and the first group of SMA actuators after cooling will passively undergo martensite non-twin transformation.

[0029] Reference Fig. 9 , describes the principle of antagonistic interaction between two SMA elements. From the perspective of macroscopic mechanics, the phase transformation of SMA from martensite to austenite can be regarded as an increase in structural stiffness. Among them, SMA spring a exhibits superelasticity under high-temperature austenite, and the force-deformation curve is approximately linear; while it exhibits nonlinear behavior at low temperatures due to the non-twin transformation of martensite. Figure 8In the given force-deformation plane, the horizontal axis represents the deformation of the structure. For SMA spring a, the characteristic quantity of this deformation is its axial length (marked as X1), which increases from left to right (i.e., the length of the spring increases). For SMA spring b, the deformation of the structure is represented by the axial length (marked as X2) and increases from right to left (this definition is mainly to establish consistency in the description of these two deformations). The left and right vertical axes are the deformation forces of SMA spring a and SMA spring b, respectively. The subscripts A and M represent the austenite and martensite phases, respectively. For example, PM represents the force of spring a in the martensite state. R1 is the unloading force of spring a in the martensite state, and R2 is the unloading force of spring b in the martensite state. The slope at any point represents the stiffness of the structure under the corresponding deformation.

[0030] The principle of the antagonistic action of SMA elements is described as follows: At the initial point O, the assembled springs a and springs b are both martensite and in a state of force equilibrium, which is the first step of the joint gait. Assume that the initial lengths of springs a and b are X0. First, spring a is energized and shrinks into an austenite shape due to the memory effect, pulling spring b to further extend. This process can be explained by the OA path, in which the new equilibrium point (point A) migrates from the martensite state of spring a to the austenite state along the martensite stiffness curve of spring b. The OA path is the second step of the joint gait. Then spring a cools down, the stiffness decreases, and the tension decreases, so that the elastic restoring force of spring b dominates, driving the two structures to recover. However, due to the hysteresis effect, the recovery path (AB) does not coincide with the martensite loading curve of spring b, but is parallel to the direction of the martensite unloading curve of spring b. Point B is another equilibrium state of the two SMA elements under martensite, which does not coincide with point O. Then spring b is driven as an active part. When heated, its stiffness increases, and spring b will shrink to the preset austenite shape, and the evolution path is BC. The ABC path is the third step of the joint gait. Finally, spring b cools down, its stiffness decreases, and the elastic recovery force of spring a dominates. Similarly, due to the hysteresis effect, the recovery path (CD) does not coincide with the martensite loading curve of spring a, but is parallel to the direction of the martensite unloading curve of spring a. This is the process of structural reset. In this way, a complete actuation cycle is completed, and point D becomes the new starting point for the next cycle. Due to the inherent hysteresis behavior of SMA, points B and D are relatively close, but they do not coincide with the initial point O. Such an ∞-shaped curve means that the input electrical heat cannot be completely converted into effective functional deformation of the joint. The areas enclosed by "DA-XA-XD" and "BC-XC-XB" represent the external work input to spring a and spring b during the stable cycle, respectively. Their overlapping part, the pentagon of "OB-XB-XD-D", is used to eliminate the influence of material hysteresis and promote system reset. Obviously, the smaller the area of ​​this area, the higher the actuation efficiency.

[0031] Reference Figure 1 , Figure 7 and Figure 8 The structural diagram of the embodiment includes an intermediate support and two connecting seats, both ends of the intermediate support are connected to the corresponding connecting seats through bearings; each connecting seat is provided with an upper and lower groups of spring connecting heads, the two upper groups of spring connecting heads facing each other are connected through SMA springs a, and the two lower groups of spring connecting heads facing each other are connected through SMA springs b, and the SMA springs a and SMA springs b are respectively located above and below the intermediate support.

[0032] The extending directions of the SMA spring a and the SMA spring b are parallel to each other, and two of each are provided.

[0033] One end of the spring connector is connected to the SMA spring, and the other end is hinged to the connecting seat where the spring connector is located.

[0034] Two micro electromagnetic locks are arranged in the middle support; a locking hole is arranged on the support platform of the connecting seat; the micro electromagnetic lock faces the support platform on its outside; in the locked state, the lock core of the micro electromagnetic lock passes through the outer wall of the middle support and is located in the corresponding locking hole.

[0035] The inner side of the connecting seat is provided with a supporting platform; the extended connecting end of the intermediate support and the supporting platform are respectively located on both sides of the bearing and realize connection with the bearing.

[0036] The intermediate support comprises a support body and a support cover; the support cover is buckled on the support body to form a closed space; the micro electromagnetic locks are all located in the closed space; the outer side of the support body is provided with an extended connection end designed integrally with it;

[0037] The bearings are provided on both sides of each support platform, and there are four bearings in total;

[0038] The outer sides of the bearings on both sides of the support platform are the ends of the support cover plate and the extended connection ends respectively.

[0039] The specific steps of the embodiment can be summarized as follows:

[0040] The initial state is Figure 2 As shown, the micro electromagnetic lock is in a power-off state and the joint is in a locked state; at the same time, the SMA spring a and the SMA spring b are in a force balance state.

[0041] In the first step, through circuit control, the micro electromagnetic lock cylinder is retracted to meet the unlocking conditions, such as Figure 3 shown.

[0042] The second step is to heat the SMA spring b, so that the spring b returns to its initial state, the overall structure contracts, and the SMA spring a is stretched, so that the spring a is in a low-temperature martensite state; at the same time, the micro electromagnetic lock circuit is disconnected, and the lock core rebounds. Figure 4 shown.

[0043] In the third step, the micro electromagnetic lock is powered on, the lock core is retracted, and the unlocking condition is achieved; the SMA spring a is heated, the spring a returns to its initial state, the overall structure is re-expanded, and the SMA spring b is stretched and is in a low-temperature martensite state. Figure 5 shown.

[0044] Step 4: The micro electromagnetic lock is powered off, the lock core pops out, the locking structure is reset, and the entire structure is locked again. Figure 6 shown.

[0045] At this point, a cycle of development is completed.

[0046] The above design provides a basic framework for the functional realization of the ultra-light large-scale circumferential antenna. In principle, the antagonistic SMA driven joint only needs one driving part. For example, if SMA spring a is used as the active part, then SMA spring b is used as the driven part. When spring a is energized, it contracts and stretches the spring b structure. Then SMA spring a dissipates heat, and the low-temperature martensite generated by the spring b structure during the stretching process will dominate the joint to return to its original state (since the austenite stiffness is significantly greater than the martensite stiffness, the tension of SMA spring a will be greatly reduced during heat dissipation). After the structure is folded, this project uses an antagonistic mutual drive mechanism to solve the expansion problem. At this time, if SMA spring b is used as the active part, then SMA spring a is used as the driven part. When SMA spring b is energized, it generates a contraction driving force to stretch the spring a structure. Then SMA spring b dissipates heat, and the spring a structure returns to its initial low-temperature martensite state.

[0047] The two SMA components in the antagonistic SMA driven joint, spring a and spring b, are both used as driving elements, and they are used alternately as active elements to drive the other. This not only achieves the required functional deformation, but also shortens the slow cooling phase of each. In addition, the controllable properties of the structure are also significantly improved. We can achieve precise control of the excitation and cooling phases of the SMA structure by setting excitation currents of different sizes and durations.

[0048] It should be noted that the above description is only a preferred application example of the present invention and is not intended to limit the protection scope of the present invention. Any technical solution using equivalent replacement or equivalent transformation is within the protection scope of the present invention.

Claims

1. A retraction and extension joint for an antenna, characterized in that: It includes an intermediate support and two connecting seats, both ends of the intermediate support are connected to the corresponding connecting seats through bearings; each connecting seat is provided with an upper and lower set of spring connecting heads, the two upper sets of spring connecting heads facing each other are connected through SMA springs a, and the two lower sets of spring connecting heads facing each other are connected through SMA springs b, and the SMA springs a and SMA springs b are respectively located above and below the intermediate support.

2. The antenna retraction and extension joint according to claim 1, characterized in that: The extending directions of the SMA spring a and the SMA spring b are parallel to each other, and two of each are provided.

3. The antenna retraction and extension joint according to claim 1, characterized in that: One end of the spring connector is connected to the SMA spring, and the other end is hinged to the connecting seat where it is located.

4. The antenna retraction and extension joint according to claim 1, characterized in that: Two micro electromagnetic locks are arranged in the middle support; a locking hole is arranged on the support platform of the connecting seat; the micro electromagnetic lock faces the support platform on its outside; in the locked state, the lock core of the micro electromagnetic lock passes through the outer wall of the middle support and is located in the corresponding locking hole.

5. The antenna retraction and extension joint according to claim 4, characterized in that: The inner side of the connecting seat is provided with a supporting platform; the extended connecting end of the intermediate support and the supporting platform are respectively located on both sides of the bearing and realize connection with the bearing.

6. The antenna retraction and extension joint according to claim 4, characterized in that: The intermediate support comprises a support body and a support cover; the support cover is buckled on the support body to form a closed space; the micro electromagnetic locks are all located in the closed space; the outer side of the support body is provided with an extended connection end designed integrally with it; The bearings are provided on both sides of each support platform, and there are four bearings in total; The outer sides of the bearings on both sides of the support platform are the ends of the support cover plate and the extended connection ends respectively.

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