CN-116276939-B - Quick-response thermally-driven spiral wound artificial muscle

Abstract

The heat-driven spiral winding type artificial muscle with the rapid response is formed by spirally winding artificial muscle fibers, the artificial muscle fibers are of a three-layer structure, a supporting sensing layer, a heat insulation layer and a driving layer are sequentially arranged from inside to outside, the driving layer is connected with an external circuit, the external circuit is used for electrically heating the driving layer to achieve shrinkage movement of the artificial muscle, the heat insulation layer prevents heat from being transferred to the supporting sensing layer to achieve rapid change of temperature of the driving layer, and the supporting sensing layer supports the artificial muscle fibers and has a sensing function. The muscle fiber is composed of an inner layer material, a middle layer material and an outer layer material, and has the functions of supporting sensing, heat insulation and driving, so that the heat of a driving layer is conducted into the material as little as possible, the energy waste is reduced, the rapid dissipation of the heat of the outer layer is ensured, and the response frequency of the artificial muscle is improved.

Inventors

• DU HAOYUAN
• LIANG YIMING
• ZHANG YANYAN
• BAI YUNHE
• QIAN CHEN

Assignees

• 之江实验室

Dates

Publication Date

20260505

Application Date

20230214

Claims (1)

1. 1. A quick-response heat-driven spiral winding type artificial muscle is characterized in that the artificial muscle is formed by spirally winding artificial muscle fibers, the artificial muscle fibers are of a three-layer structure, the cross sections of the artificial muscle fibers form a three-layer concentric circular structure, a circular supporting and sensing layer, an annular heat-insulating layer and an annular driving layer are sequentially arranged from inside to outside, the driving layer is connected with an external circuit, the external circuit is used for electrifying and heating the driving layer so as to realize the contraction movement of the artificial muscle, the heat-insulating layer reduces the heat transfer to the supporting and sensing layer so as to realize the quick change of the temperature of the driving layer, the supporting and sensing layer supports the artificial muscle fibers, and the supporting and sensing layer adopts shape memory alloy wires; The driving layer is made of nylon film with silver plated on the surface; The heat insulation layer is a polyimide film; The diameter of the artificial muscle fiber is between 20 and 200 mu m; the thickness of the supporting sensing layer is larger than that of the driving layer; the thickness of the driving layer is 4-40 mu m; the thickness of the heat insulation layer is 1-10 mu m; the thickness of the supporting sensing layer is 10-120 mu m.

Description

Quick-response thermally-driven spiral wound artificial muscle Technical Field The invention relates to the technical field of artificial muscles, in particular to a quick-response heat-driven spiral winding type artificial muscle. Background As a flexible driver, artificial muscles can convert external energy into mechanical energy, and they are receiving much attention by virtue of low noise, large stroke and better biocompatibility, and have a wide and huge application potential in exoskeleton, artificial limbs, and biomimetic robots. Currently, many functional materials have been used as artificial muscles, such as pneumatic porous materials, shape Memory Alloys (SMA), shape Memory Polymers (SMP), nylon fibers, dielectric Elastomers (DEA), ionic Polymer Metal Composites (IPMC), carbon Nanotubes (CNT), magnetorheological fluids, and the like. The common artificial muscles are mainly divided into five types of pneumatic response, temperature response, chemical response, electric response and magnetic response according to the driving principle, wherein the temperature response, namely the thermally driven artificial muscles, are more common types. One type of thermally driven artificial muscle that is important is a spiral wound artificial muscle. Spirally wound artificial muscles are usually driven by means of thermal (electrochemical, photonic, thermal or electrothermal) contraction and exhibit excellent torsional and tensile driving properties, with maximum contractions typically up to 40-50% and higher energy densities. Among them, the spiral wound artificial muscle driven by electric heat is widely used because it has advantages of easy operation and control. In general, thermally driven spirally wound artificial muscles contract when electrically heated and expand when de-energized, both the heating and cooling processes of which affect the driving frequency. The heating process can be shortened by increasing the input power, while the cooling process is largely uncontrollable in ambient air. Thus, the drive frequency of the electro-thermally driven artificial muscles tends to be low, typically below 3Hz, and is limited primarily by the cooling time, which limits their application as fast response drivers. One of the methods of increasing the heat dissipation rate is to improve the heat dissipation conditions such as forced air cooling or water cooling, but this generally requires higher energy consumption. To solve this problem, a specific driving principle of the spiral wound artificial muscle is analyzed. In the spiral wound artificial muscle, the yarn constituting the muscle is formed by twisting a fiber such as nylon, and the wound yarn is heated to expand in volume to cause untwisting, and further to cause contraction of the wound muscle. From a structural point of view, the ability of the fiber expansion to drive the yarn to untwist increases as the offset angle of the yarn (the angle between the yarn axis and the fiber axis) increases, and since the offset angle decreases gradually from the surface to the center of the yarn, the closer to the center of the yarn the smaller the contribution to driving is, and the lower the energy utilization efficiency is naturally. And the electric heating type spiral winding artificial muscle is not easy to reduce in temperature because the inside of the electric heating type spiral winding artificial muscle cannot effectively exchange heat with the external environment when the electric heating type spiral winding artificial muscle works, and the electric heating type spiral winding artificial muscle is one of reasons for low driving frequency of the electric heating type driving artificial muscle. From the above analysis, it can be seen that if the response frequency and energy utilization rate of the spiral wound artificial muscle are to be effectively improved, the improvement design can be achieved by utilizing the structural characteristics of the spiral wound artificial muscle. CN112201744a discloses the preparation and application of an electrostrictive spiral wound artificial muscle. The muscle fiber in the invention is composed of a sheath and a core, wherein the sheath is made of a carbon nano tube film, the core is made of nylon wires, and the whole muscle contraction is achieved by electrifying and heating the sheath layer. Although carbon nanotubes are very excellent thermally driven materials with good electrical conductivity and mechanical properties, they are expensive, rendering the manufactured artificial muscles expensive and unfavorable for large-scale commercial applications. In addition, since the sheath layer and the core layer of the muscle fiber are in direct contact, heat can be sufficiently transferred to the core layer upon heating driving. When artificial muscle dispels the heat, because outside carbon nanotube radially dissipates heat ability not good, causes its inside heat unable quick dissipation to forming a relative high