阅读说明：本技术 一种具有热缩冷胀超材料特性的致动装置 (Actuating device with hot-shrinkage and cold-expansion metamaterial characteristics ) 是由 文桂林 欧海锋 刘杰 于 2019-10-17 设计创作，主要内容包括：本发明涉及一种具有热缩冷胀超材料特性的致动装置,包括动力单元和剪叉单元；动力单元至少有一个,剪叉单元有若干个,动力单元与剪叉单元铰接,剪叉单元与动力单元或与相邻的剪叉单元铰接,所有的剪叉单元和动力单元形成一个封闭环；动力单元包括第一连接块、第二连接块、位于第一连接块和第二连接块之间的智能材料；第一连接块和第二连接块均与智能材料固定连接,剪叉单元包括两条相互铰接的剪叉臂；第一连接块的一端和第二连接块的一端分别与其中一个相邻的剪叉单元的两条剪叉臂铰接,第一连接块的另一端和第二连接块的另一端分别与另外一个相邻的剪叉单元的两条剪叉臂铰接。本发明能根据温度变化做出热缩冷胀响应,属于致动装置的技术领域。(The invention relates to an actuating device with the characteristics of a thermal shrinkage and cold expansion metamaterial, which comprises a power unit and a scissor unit, wherein the power unit is connected with the scissor unit; the power unit is at least one, the number of the scissor units is a plurality, the power unit is hinged with the scissor units, the scissor units are hinged with the power unit or the adjacent scissor units, and all the scissor units and the power unit form a closed ring; the power unit comprises a first connecting block, a second connecting block and an intelligent material positioned between the first connecting block and the second connecting block; the first connecting block and the second connecting block are fixedly connected with the intelligent material, and the shearing fork unit comprises two shearing fork arms which are hinged with each other; one end of the first connecting block and one end of the second connecting block are respectively hinged with two scissor arms of one adjacent scissor unit, and the other end of the first connecting block and the other end of the second connecting block are respectively hinged with two scissor arms of the other adjacent scissor unit. The invention can make thermal shrinkage and cold expansion response according to temperature change, and belongs to the technical field of actuating devices.)

1. An actuating device with characteristics of a heat-shrinkable and cold-expandable metamaterial, characterized in that: comprises a power unit and a scissors unit; the power unit is at least one, the number of the scissor units is a plurality, the power unit is hinged with the scissor units, the scissor units are hinged with the power unit or the adjacent scissor units, and all the scissor units and the power unit form a closed ring;

the power unit comprises a first connecting block, a second connecting block and an intelligent material positioned between the first connecting block and the second connecting block; the intelligent material has the characteristics of expansion with heat and contraction with cold, the first connecting block and the second connecting block are fixedly connected with the intelligent material, and the shearing fork unit comprises two shearing fork arms which are hinged with each other; one end of the first connecting block and one end of the second connecting block are respectively hinged with two scissor arms of one adjacent scissor unit, the other end of the first connecting block and the other end of the second connecting block are respectively hinged with two scissor arms of the other adjacent scissor unit, and the two scissor arms of one scissor unit are respectively hinged with the two scissor arms of the other scissor unit between the two adjacent scissor units.

2. An actuator device having the properties of a heat-shrinkable cold-expandable metamaterial as claimed in claim 1, wherein: the power unit further comprises a straight shaft; the intelligent material is shape memory spring, is equipped with the shaft hole on the second connecting block, the one end and the first connecting block fixed connection of straight axle, and the shaft hole of second connecting block is passed to the other end of straight axle, and second connecting block slidingtype is installed on the straight axle, shape memory spring's cover on the straight axle and shape memory spring's both ends respectively with first connecting block, second connecting block fixed connection.

3. An actuator device having the properties of a heat-shrinkable cold-expandable metamaterial as claimed in claim 3, wherein: the scissor fork arms are bent, hinge holes and hinges are arranged at the bent positions of the scissor fork arms, and the two scissor fork arms of the same scissor fork unit are hinged to each other through the hinges and penetrating through the hinge holes at the bent positions.

4. An actuator device having the properties of a heat-shrinkable cold-expandable metamaterial as claimed in claim 1, wherein: both ends of the scissor arm, the first connecting block and the second connecting block are provided with hinge holes and hinges, and the first connecting block and the second connecting block penetrate through the hinge holes through the hinges and are hinged to the scissor arm.

5. An actuator device having the properties of a heat-shrinkable cold-expandable metamaterial as claimed in claim 1, wherein: the first connecting block, the second connecting block and the scissor fork arm are all made of rigid materials.

6. An actuator device having the properties of a heat-shrinkable cold-expandable metamaterial as claimed in claim 3, wherein: the power units are four, the four power units are distributed on the closed ring at an angle of 90 degrees, and four scissor units are arranged between every two adjacent power units.

7. An actuator device having the properties of a heat-shrinkable cold-expandable metamaterial as claimed in claim 6, wherein: the angle of bending of the scissor arms is 157.5 degrees.

8. An actuator device having the properties of a heat-shrinkable cold-expandable metamaterial as claimed in claim 2, wherein: the straight shaft, the first connecting block and the second connecting block of the same power unit are all located on the same radius of a closed ring formed by all the scissor units and the power unit, and the distance between the first connecting block and the center of the closed ring is larger than that between the second connecting block and the center of the closed ring.

9. An actuator device having the properties of a heat-shrinkable cold-expandable metamaterial as claimed in claim 2, wherein: the first connecting block and the second connecting block are both I-shaped.

Technical Field

The invention relates to the technical field of precision instruments and thermal actuators with temperature fluctuation, in particular to an actuating device with the characteristics of a thermal shrinkage and cold expansion metamaterial.

Background

The structure with the thermal shrinkage and cold expansion characteristics shows special performance opposite to common substances under the condition of temperature fluctuation, and the special performance has important significance in the fields of optical instruments, precision instruments, thermal actuators and the like. However, the structures which are hot and cold to swell in nature usually have the defects of poor mechanical performance, difficult prediction and adjustment of mechanical response and the like, so that the application of the structures in practical engineering is limited. In response to these shortcomings, many researchers in recent years have also achieved artificially predicting or adjusting the thermomechanical response of structures by purposefully designing periodically arranged unit cell structures or selecting appropriate materials to design heat-shrink and cold-swell superstructures. Most of these new structures achieve thermal shrinkage and cold expansion properties from the difference in thermal expansion between two material compositions with different coefficients of thermal expansion, combined with highly complex geometries. Although the heat-shrinkable cold-expandable superstructure has more obvious heat-shrinkable cold-expandable characteristics compared with natural materials. But their stretch ratios are still small, and the mechanical response is often difficult to predict and adjust accurately; meanwhile, the joint formed by two or more materials is easy to generate obvious stress concentration, and the joint of two different materials causes difficulty in processing and manufacturing.

Disclosure of Invention

Aiming at the technical problems in the prior art, the invention aims to: the actuating device has the characteristics of the thermal shrinkage and cold expansion metamaterial, has a high expansion ratio under small temperature fluctuation, avoids obvious stress concentration, and is easy to process and manufacture.

In order to achieve the purpose, the invention adopts the following technical scheme:

an actuating device with the characteristics of a thermal shrinkage and cold expansion metamaterial comprises a power unit and a scissor unit; the power unit is at least one, the number of the scissor units is a plurality, the power unit is hinged with the scissor units, the scissor units are hinged with the power unit or the adjacent scissor units, and all the scissor units and the power unit form a closed ring;

the power unit comprises a first connecting block, a second connecting block and an intelligent material positioned between the first connecting block and the second connecting block; the intelligent material has the characteristics of expansion with heat and contraction with cold, the first connecting block and the second connecting block are fixedly connected with the intelligent material, and the shearing fork unit comprises two shearing fork arms which are hinged with each other; one end of the first connecting block and one end of the second connecting block are respectively hinged with two scissor arms of one adjacent scissor unit, the other end of the first connecting block and the other end of the second connecting block are respectively hinged with two scissor arms of the other adjacent scissor unit, and the two scissor arms of one scissor unit are respectively hinged with the two scissor arms of the other scissor unit between the two adjacent scissor units. When the intelligent material expands with heat and contracts with cold, the two scissor arms of all the scissor units can rotate, and finally the whole actuating device presents the characteristic of thermal shrinkage and cold expansion.

Further, the method comprises the following steps: the power unit further comprises a straight shaft; the intelligent material is shape memory spring, is equipped with the shaft hole on the second connecting block, the one end and the first connecting block fixed connection of straight axle, and the shaft hole of second connecting block is passed to the other end of straight axle, and second connecting block slidingtype is installed on the straight axle, shape memory spring's cover on the straight axle and shape memory spring's both ends respectively with first connecting block, second connecting block fixed connection. The shape memory spring can expand with heat and contract with cold, when the shape memory spring is extended, the whole actuating device can contract, and when the shape memory spring is shortened, the whole actuating device can expand.

Further, the method comprises the following steps: the scissor fork arms are bent, hinge holes and hinges are arranged at the bent positions of the scissor fork arms, and the two scissor fork arms of the same scissor fork unit are hinged to each other through the hinges and penetrating through the hinge holes at the bent positions.

Further, the method comprises the following steps: both ends of the scissor arm, the first connecting block and the second connecting block are provided with hinge holes and hinges, and the first connecting block and the second connecting block penetrate through the hinge holes through the hinges and are hinged to the scissor arm.

Further, the method comprises the following steps: the first connecting block, the second connecting block and the scissor fork arm are all made of rigid materials. The rigid material is insensitive to temperature, ensuring the uniqueness of the movement of the whole actuating device.

Further, the method comprises the following steps: the power units are four, the four power units are distributed on the closed ring at an angle of 90 degrees, and four scissor units are arranged between every two adjacent power units. The multiple power units make the entire actuator more sensitive to thermal shrinkage and cold expansion.

Further, the method comprises the following steps: the angle of bending of the scissor arms is 157.5 degrees.

Further, the method comprises the following steps: the straight shaft, the first connecting block and the second connecting block of the same power unit are all located on the same radius of a closed ring formed by all the scissor units and the power unit, and the distance between the first connecting block and the center of the closed ring is larger than that between the second connecting block and the center of the closed ring. The position of the first connecting block of the actuating device is kept unchanged in the thermal shrinkage and cold expansion process, and the whole formed by the second connecting block, the intelligent material and the scissor unit has the thermal shrinkage and cold expansion characteristic.

Further, the method comprises the following steps: the first connecting block and the second connecting block are both I-shaped.

In summary, the present invention has the following advantages:

the invention provides an actuating device with the characteristics of a thermal shrinkage and cold expansion metamaterial. The intelligent material adopted by the invention can accurately predict and adjust the mechanical response of the actuating device, and the annular structure can also predict the motion track of the actuating device through the kinematics principle, so that the mechanical response of the whole actuating device can also be accurately predicted and adjusted. Meanwhile, the intelligent material avoids stress concentration in the long-term temperature cycle process. According to the combination of the intelligent material and the rigid material, the joint of the two materials only needs to be fixedly connected, the thermal expansion between the two different materials cannot cause great influence on mechanical response, and the combination is easier to manufacture. The invention has simple structure and only has one degree of freedom; compared with the same type of metamaterial, the response expansion ratio is obviously improved, and meanwhile, the actuating device is always in a ring shape with different sizes in the motion process.

Drawings

Fig. 1 is a schematic structural view of the present actuator device.

Fig. 2 is a schematic structural view of the scissors unit and the power unit.

Figure 3 is a schematic view of the expansion state of the present actuator as the temperature decreases.

Figure 4 is a schematic view of the present actuator in a contracted state when the temperature increases.

Figure 5 is a schematic diagram of the present actuator design.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and detailed description.

To facilitate a uniform view of the various reference numbers within the drawings, reference numbers appearing in the drawings are now described collectively as follows:

the scissors unit is 1, the first connecting block is 2, the second connecting block is 3, the scissors arm is 4, the straight shaft is 5, and the shape memory spring is 6.

Referring to fig. 1, 2, 3 and 4, an actuating device with the characteristics of a heat-shrinkable and cold-expandable metamaterial comprises a power unit and a scissor unit; the power unit is at least one, the number of the scissor units is a plurality, the power unit is hinged with the scissor units, the scissor units are hinged with the power unit or the adjacent scissor units, and all the scissor units and the power unit form a closed ring; the structure of the closed loop is not limited to a circular interface, and can also be extended to other two-dimensional or three-dimensional expandable mechanisms, such as a square expandable mechanism, a spherical expandable mechanism, and the like. The power unit is only hinged with the scissor unit, the scissor unit can be hinged with the power unit, and the scissor unit can also be hinged with other scissor units.

The power unit comprises a first connecting block, a second connecting block and an intelligent material positioned between the first connecting block and the second connecting block; the intelligent material has the characteristics of expansion with heat and contraction with cold, the first connecting block and the second connecting block are fixedly connected with the intelligent material, and the shearing fork unit comprises two shearing fork arms which are hinged with each other; the two ends of the power unit are adjacent to one scissor unit, the two ends of the power unit are hinged to the scissor unit, one end of the first connecting block and one end of the second connecting block are hinged to two scissor arms of one adjacent scissor unit, and the other end of the first connecting block and the other end of the second connecting block are hinged to two scissor arms of the other adjacent scissor unit. When two adjacent scissors units are hinged with each other, namely the two scissors units are hinged with each other, the tail ends of the two scissors arms of one of the scissors units are respectively hinged with the tail ends of the two scissors arms of the other scissors unit. The intelligent material is as thermal drive under the temperature fluctuation, and the intelligent material can produce expend with heat and contract with cold according to temperature variation, and the actuating device of closed loop structure produces mechanical response under the drive of intelligent material, and the distance between first connecting block and the second connecting block changes, and two scissors fork arms of same scissors fork unit rotate around the point of mutual articulated, and two adjacent scissors fork units rotate each other for whole actuating device demonstrates thermal shrinkage and expands with cold characteristic. The closed loop configuration allows a single degree of freedom of movement for the actuator.

The power unit further comprises a straight shaft; the intelligent material is shape memory spring, is equipped with the shaft hole on the second connecting block, the one end and the first connecting block fixed connection of straight axle, and the shaft hole of second connecting block is passed to the other end of straight axle, and second connecting block slidingtype is installed on the straight axle, shape memory spring's cover on the straight axle and shape memory spring's both ends respectively with first connecting block, second connecting block fixed connection. The smart material is not limited to a certain material, but a series of materials with high positive thermal expansion coefficients, such as a two-way shape memory spring, a two-way shape memory polymer and the like, which can expand with heat and contract with cold. The shape memory spring can sense the change of temperature, and when the temperature rose, the shape memory spring can extend to make the second connecting block slide on the straight axle and keep away from first connecting block, and whole actuating device presented a state of contracting at last, and when the temperature dropped, the shape memory spring can shorten, thereby made the second connecting block slide on the straight axle and be close to first connecting block, and whole actuating device presented an expanded state at last.

In this example, there are four power units, four of which are distributed on the closed ring at 90 °, and four scissor units are arranged between two adjacent power units.

The straight shaft, the first connecting block and the second connecting block of the same power unit are all located on the same radius of a closed ring formed by all the scissor units and the power unit, and the distance between the first connecting block and the center of the closed ring is larger than that between the second connecting block and the center of the closed ring. The second connecting block is closer to the center of the closed loop than the first connecting block.

The scissor arms are bent, and the bending angle of the scissor arms is 157.5 degrees. The bending part of the scissor fork arm is provided with a hinge hole and a hinge, and two scissor fork arms of the same scissor fork unit are hinged to each other through the hinge hole at the bending part through the hinge. The matching of the hinge and the hinge hole can allow the two scissor arms to rotate mutually.

Both ends of the scissor arm, the first connecting block and the second connecting block are provided with hinge holes and hinges, and the first connecting block and the second connecting block penetrate through the hinge holes through the hinges and are hinged to the scissor arm. The hinge is matched with the hinge hole to allow the scissor arm to rotate around the first connecting block or the second connecting block. The first connecting block and the second connecting block are both I-shaped. The shearing fork arm is hinged in the groove of the first connecting block or the second connecting block, the shearing fork arm can be more stable when rotating, and the I-shaped first connecting block and the I-shaped second connecting block can prevent the shearing fork arm from deviating to the axis direction of the hinge hole.

The first connecting block, the second connecting block and the scissor fork arm are all made of rigid materials. The hinge and the scissors arms can be made of rigid materials insensitive to temperature according to specific use occasions.

Through the careful design of relevant size parameters of the scissor arms, the scissor units and the power units can be hinged to form a closed ring structure. Meanwhile, hinge holes are distributed at two ends and bent parts of the scissor arm and used for installing hinges. The hinge generally adopts a snap rivet for connecting the scissor arms, the first connecting block, the second connecting block and the like into a closed ring structure. Because the hinge allows mutual rotation between the two scissor arms and between the scissor arms and the first connecting block and the second connecting block, the actuating device can contract or extend within a reasonable size range.

The actuating device is also called as an actuator or an actuating mechanism, and is used for converting equal non-mechanical quantity output by the controller into mechanical quantity such as strain, displacement and force so as to achieve the purposes of strain driving, displacement driving and force driving on a control object. The actuating device has the characteristics of a thermal shrinkage and cold expansion material, and can convert temperature change into mechanical energy of a spring and finally convert the mechanical energy into displacement and force.

As shown in fig. 1, 3, 4, and 5, since the closed ring structure is a perfect circle with high-level symmetry, in fig. 5, the annular superstructure also maintains a circular shape during the movement as long as the included angle α remains constant.

Specifically, the premise that the scissor unit and the power unit are connected into a single-degree-of-freedom closed ring structure is that the following conditions are required to be met:

wherein N is the number of the scissor units, and β is the scissor arm l₁And l₂The included angle therebetween.

Scissor fork arm₁The included angle theta between the Z axis is the following relation:

the relationship between the diameter of the closed loop and the length h of the shape memory spring can be expressed according to the kinematic principle as:

in order to quantify the mechanical response of the superstructure with temperature change, it is also necessary to obtain a constitutive model of the shape memory spring. By appropriate modification of the Brinson constitutive model of the shape memory spring, it can be deduced that the deformation quantity Δ λ of the shape memory spring is:

wherein n is the effective number of turns of the shape memory spring, D_sIs the diameter of the shape memory spring, d is the diameter of the shape memory spring wire, k is the stress formula correction factor, and γ is the shear strain.

The relation between the diameter D of the closed ring and the temperature T can be obtained by combining the formula (4) and the formula (5), and can be expressed as

In order to better understand the thermal shrinkage and cold expansion characteristics of the proposed actuator, the expansion ratio is theoretically derived to quantitatively predict its and mechanical response when measured by T at temperature₀Change to T₀At + Δ T, the ratio of expansion and contraction is

The mechanical response can be accurately predicted and adjusted according to equations (6) and (7).

The working principle of the actuating device is as follows: as a smart material for thermal drives, thermal deformation of the smart material can carry internal forces throughout the actuator and cause a thermal shrinkage and cold expansion response of the actuator. The actuator has a single degree of freedom of movement. When the temperature rises, the shape memory spring expands, causing the shape memory spring to elongate; substituting internal forces into the entire actuator results in the actuator compressing toward the mid-gap, ultimately taking up less space. When the temperature decreases, the shape memory spring contracts, causing the shape memory spring to shorten, thereby causing the actuator to expand outward, eventually taking up more space. The present actuator thus exhibits the properties of a heat-shrinkable cold-expandable material throughout the actuator under a combination of thermal strain and mechanical response. The invention can predict and adjust the thermal shrinkage and cold expansion response in a large range and accurately in a small temperature fluctuation range.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.