CN114992073A

CN114992073A - Microchannel shape memory alloy tube, method of use and actuator

Info

Publication number: CN114992073A
Application number: CN202210594121.8A
Authority: CN
Inventors: 刘琎; 吴朔阳; 樊一桐; 唐鼎; 王伟明; 汪华苗
Original assignee: Shanghai Jiaotong University
Current assignee: Shanghai Jiaotong University
Priority date: 2022-05-27
Filing date: 2022-05-27
Publication date: 2022-09-02

Abstract

The invention provides a micro-channel shape memory alloy tube, a using method and a driver, comprising the following steps: a microchannel SMA tube and an energizing terminal; the microchannel SMA tube is set to be tubular and allows a capillary phenomenon to occur when liquid flows in, and the microchannel SMA tube is made of shape memory alloy; the microchannel SMA pipe is connected with a cooling liquid source, and allows cooling liquid to flow in from one end and flow out from the other end; two ends of the microchannel SMA pipe are connected with the electrified terminals and are electrified and heated through the electrified terminals; when the microchannel SMA pipe is electrified and heated, the microchannel SMA pipe contracts, and when the microchannel SMA pipe stops heating and the cooling liquid flows inside the microchannel SMA pipe, the microchannel SMA pipe does not contract any more. According to the invention, the SMA material is made into the micro-channel, and the heat dissipation is enhanced by utilizing the characteristics of the capillary effect and the large specific surface area of the micro-channel, so that the SMA material has the functions of driving and heat dissipation, and the problems of slow cooling and low response frequency of the traditional SMA wire can be solved.

Description

Microchannel shape memory alloy tube, method of use and actuator

Technical Field

The invention relates to the field of driving elements, in particular to a micro-channel type shape memory alloy tube, a using method and a driver.

Background

With the continuous penetration of the robot to the daily life of the human being, human-computer interaction application scenes which are mainly characterized by high unstructured and human-computer contact emerge continuously, and the scenes usually need the robot to have higher safety and flexibility, so that the flexible driver receives more and more attention. Common flexible driving mechanisms are mainly: fluid pressure actuation, electro-active material actuation, and thermal phase change material actuation. As shown in the following table, the pneumatic driving performance is moderate, and the pneumatic driving performance is most widely applied to the soft robot at present, and the main limitation is that the miniaturization is difficult; the bandwidth of the dielectric elastic material can reach 1kHz, but the dielectric elastic material needs kilovolt high-voltage driving, and is mainly applied to a laboratory scene at present; shape Memory Alloys (SMAs) have very large available stresses and energy densities and are easy to miniaturize, but too low a bandwidth makes them difficult to apply in scenarios where fast response is required. Therefore, if the short plate with low SMA bandwidth can be complemented, the advantages of high SMA energy density and large driving force can be fully exerted, the application range of the SMA in the fields of soft robots, aerospace, biomedical treatment and the like is greatly expanded, and the method has important significance.

Flexible drive mechanism	Bandwidth (Hz)	Stress (MPa)	Energy density (J/cm) ³ )
				Biological muscle	2-1000	0.1-1	0.008-0.04
Air pressure drive	<20	<3.4	<0.5
				Dielectric elastic drive	<1000	<7.2	<3.5
Shape memory alloy	<3	<700	<10

The basic principle of SMA drive is thermal phase change, so the bandwidth of the SMA drive depends on the duration of two strokes of heating actuation and cooling return, and longer cooling time is a main problem resulting in low bandwidth of the SMA drive. At present, the improvement of the heat dissipation environment becomes a basic idea for improving the cooling speed of SMA, and the existing method mainly comprises the step of placing SMA filaments in a medium with high heat conductivity coefficient or creating a forced convection heat dissipation environment, specifically, the schemes of air cooling, water cooling, heat conduction silicone grease and the like are adopted. In the research related to water cooling, a silicone tube is adopted to wrap SMA filaments, and cooling water is introduced into the silicone tube, so that the highest response frequency of 0.33Hz can be realized.

The microchannel generally refers to a pipeline with the inner diameter of 10-1000 microns, and because the pipe diameter is extremely small, a capillary phenomenon can occur under the condition of soaking liquid, which is represented by that the liquid actively rises or falls along the pipeline, and the higher the water temperature is, the faster the movement is. In addition, the microchannel has larger specific surface area and outstanding heat exchange performance, and is widely applied to the field of heat exchangers. For example, in the 90 s of the 20 th century, a pulsating heat pipe is proposed, which is made by bending a microchannel pipe into a serpentine structure, wherein a working medium in the pipe continuously changes phase and oscillates and convects between a cold end and a hot end, so that high-efficiency heat transfer is realized, and the pulsating heat pipe is a heat transfer element with high heat flow density, miniaturization and low cost.

Accordingly, it would be desirable to provide an actuation element having a micro-channel structure in combination with a shape memory alloy material to increase the response frequency of an SMA actuator.

Through the literature search of the prior art, the Chinese patent grant publication number is CN104847611A, and the name is: a shape memory alloy actuator based on micro-pipe cooling. The apparatus comprises: the flexible packaging material comprises a flexible packaging material, a micro-pipeline, an elastic plate, an SMA wire and a positioning plate thereof, wherein the micro-pipeline, the elastic plate and the SMA wire are all completely embedded in the flexible packaging material. The micro-pipeline is a cavity pipeline in the flexible material, and the cooling liquid realizes the cold and heat exchange of the driver in the rapid circulating flow process in the micro-pipeline, thereby achieving the purpose of heat dissipation. The principle of accelerating cooling is a basic idea of continuously improving the heat dissipation environment, but the improvement of the cooling speed is limited due to the fact that the structure of the SMA material is not improved.

Disclosure of Invention

In view of the defects in the prior art, the present invention provides a microchannel shape memory alloy tube, a method of using the same, and a driver.

According to the present invention, there is provided a microchannel shape memory alloy tube comprising: a microchannel SMA tube and an energizing terminal;

the microchannel SMA tube is tubular and allows a capillary phenomenon to occur when liquid flows in, and the microchannel SMA tube is made of shape memory alloy;

the microchannel SMA pipe is connected with a cooling liquid source, and the microchannel SMA pipe allows cooling liquid to flow in from one end and flow out from the other end;

two ends of the microchannel SMA pipe are connected with an electrified terminal and are electrified and heated through the electrified terminal;

when the microchannel SMA tube is electrified and heated, the microchannel SMA tube contracts;

when the microchannel SMA pipe stops heating and the cooling liquid flows through the microchannel SMA pipe, the microchannel SMA pipe does not shrink any more.

Preferably, the invention aims at improving the structure of the SMA wire and provides the microchannel type SMA pipe. The microchannel SMA tube can be used as a driving element and a heat dissipation element, and can generate efficient convection heat dissipation through a microchannel structure, so that the cooling speed of the SMA material is greatly improved.

Preferably, when the microchannel SMA tube adopts a one-way memory effect shape memory alloy, the microchannel SMA tube is provided with a resetting device, and the microchannel SMA tube is reset through the resetting device.

Preferably, the microchannel SMA tube has an outer diameter of 1-2mm and an inner diameter of 0.01-1 mm.

Preferably, the shape memory alloy is one or more of a nickel-titanium based, copper based and iron based memory alloy.

Preferably, the energizing terminal is connected to a power source.

Preferably, a check valve is arranged between the microchannel SMA tube and the cooling liquid source, and the microchannel SMA tube realizes on-off control of the cooling liquid through the check valve.

Preferably, the use method of the microchannel shape memory alloy tube comprises the following steps:

step S1, installing the microchannel SMA tube into a driver and connecting a power-on terminal, a cooling liquid source and a resetting device;

step S2, the electrifying terminal is electrified to heat the microchannel SMA tube, and the microchannel SMA tube contracts;

step S3, the electrified terminal is powered off, and the heating of the microchannel SMA tube is stopped;

step S4, enabling cooling liquid in the cooling liquid source to flow in from one end of a micro-channel SMA pipe, enabling the other end of the micro-channel SMA pipe to flow out, enabling the micro-channel SMA pipe to generate a capillary phenomenon to push the cooling liquid to flow at the same time, and enabling the micro-channel SMA pipe not to shrink any more;

and step S5, the microchannel SMA pipe is assisted to reset through a resetting device.

Step S6, repeating steps S1 to S5 until the driver stops driving.

Preferably, an actuator employs the microchannel shape memory alloy tube.

Preferably, the SMA is a shape memory alloy and the cooling fluid comprises air, water, and liquid nitrogen.

Preferably, the contraction direction of the microchannel SMA tube is an axial direction.

Compared with the prior art, the invention has the following beneficial effects:

1. according to the invention, the SMA material is made into the micro-channel, and the heat dissipation is enhanced by utilizing the characteristics of the micro-channel, such that the SMA material has both driving and heat dissipation functions, and the problems of slow cooling and low response frequency of the traditional SMA wire can be solved;

2. the invention can fully exert the advantages of large available stress and large power density of the SMA material, and can be used for preparing the SMA flexible driver.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is a schematic diagram of microchannel SMA tubing connection;

FIG. 2 is a schematic structural view of a microchannel SMA tube;

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.

Example 1

As shown in fig. 1 and 2, the present embodiment may be used for an SMA flexible actuator, including: the micro-channel SMA tube 1 and the energizing terminal 2; the microchannel SMA tube 1 is tubular and allows a capillary phenomenon to occur when liquid flows in, the microchannel SMA tube 1 is made of shape memory alloy, the microchannel SMA tube 1 is connected with a cooling liquid source, the microchannel SMA tube 1 allows the cooling liquid to flow in from one end and flow out from the other end, and two ends of the microchannel SMA tube 1 are connected with an energizing terminal 2 and are energized and heated through the energizing terminal 2; the micro-channel SMA tube 1 has an outer diameter of 1-2mm and an inner diameter of 0.01-1mm, and the shape memory alloy is one or more of nickel-titanium, copper and iron memory alloys.

When the microchannel SMA pipe 1 is electrified and heated, the microchannel SMA pipe 1 contracts, and when the microchannel SMA pipe 1 stops heating and the inside of the microchannel SMA pipe 1 circulates cooling liquid, the microchannel SMA pipe 1 does not contract any more. The energizing terminal 2 is connected to a power source 3. And a check valve is arranged between the microchannel SMA pipe 1 and a cooling liquid source, and the microchannel SMA pipe 1 realizes on-off control of the cooling liquid through the check valve. When the microchannel SMA tube 1 adopts the one-way memory effect shape memory alloy, the microchannel SMA tube 1 is provided with a resetting device, and the microchannel SMA tube 1 is reset through the resetting device.

The using method of the embodiment comprises the following steps: step S1, installing the micro-channel SMA tube 1 into a driver and connecting the electrifying terminal 2, the cooling liquid source and the resetting device; step S2, electrifying the electrifying terminal 2 to heat the microchannel SMA pipe 1, and contracting the microchannel SMA pipe 1; step S3, powering off the electrified terminal 2, and stopping heating the microchannel SMA tube 1; step S4, cooling liquid in a cooling liquid source flows in from one end of the micro-channel SMA tube 1, the other end of the micro-channel SMA tube 1 flows out, the micro-channel SMA tube 1 simultaneously generates a capillary phenomenon to push the cooling liquid to flow, and the micro-channel SMA tube 1 does not shrink any more; step S5, the microchannel SMA tube 1 is assisted to reset through a resetting device; step S6, repeating steps S1 to S5 until the driver stops driving.

Example 2

Example 2 is a preferred example of example 1.

As shown in fig. 1 and 2, the present embodiment includes: microchannel SMA tubular product 1, circular telegram terminal 2 and power 3. Two ends of the micro-channel SMA tube 1 are respectively provided with an electrified terminal 2 which is connected with a power supply 3 through a lead.

The microchannel SMA tube 1 is a metal pipeline made of shape memory alloy through a drawing process, the specific material of the microchannel SMA tube can be one or more of nickel-titanium memory alloy, copper memory alloy and iron memory alloy, and the thermal shrinkage direction is along the longitudinal direction of the pipeline. The micro-channel SMA tube 1 has an outer diameter of 1-2mm and an inner diameter of 0.01-1 mm. If a one-way memory effect shape memory alloy is used, a means for providing a restoring force during the cooling stage is required.

The function of the electrifying terminal 2 is to connect the microchannel SMA tube into the circuit, and the power supply 3 has the function of heating the SMA and can be a direct current power supply or an alternating current power supply.

The working principle of the embodiment is as follows: the microchannel SMA pipe 1 has a thermal shrinkage effect along the axial direction and is connected to a power supply 3 through a power-on terminal 2. When the power supply 3 supplies power, the generated joule heat enables the temperature rise and the phase change of the microchannel SMA tube 1 to generate contraction motion; when the power supply is stopped, cooling liquid can be introduced from one end of the micro-channel SMA tube 1, the cooling liquid can be air, water, liquid nitrogen and the like, the cooling liquid and the tube wall generate strong convection heat transfer, and finally heat is taken out from the other end, so that the micro-channel SMA tube 1 is rapidly cooled and restored.

Those skilled in the art will appreciate that, in addition to implementing the system and its various devices, modules, units provided by the present invention as pure computer readable program code, the system and its various devices, modules, units provided by the present invention can be fully implemented by logically programming method steps in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers and the like. Therefore, the system and various devices, modules and units thereof provided by the invention can be regarded as a hardware component, and the devices, modules and units included in the system for realizing various functions can also be regarded as structures in the hardware component; means, modules, units for performing the various functions may also be regarded as structures within both software modules and hardware components for performing the method.

In the description of the present application, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.

Claims

1. A microchannel shape memory alloy tube, comprising: the micro-channel SMA tube comprises a micro-channel SMA tube (1) and an energizing terminal (2);

the microchannel SMA tube (1) is tubular and allows a capillary phenomenon to occur when liquid flows in, and the microchannel SMA tube (1) is made of shape memory alloy;

the microchannel SMA tube (1) is connected with a cooling liquid source, and the microchannel SMA tube (1) allows the cooling liquid to flow in from one end and flow out from the other end;

two ends of the microchannel SMA pipe (1) are connected with an electrified terminal (2) and are electrified and heated through the electrified terminal (2);

when the microchannel SMA pipe (1) is electrified and heated, the microchannel SMA pipe (1) contracts;

when the micro-channel SMA pipe (1) stops heating and the cooling liquid flows through the interior of the micro-channel SMA pipe (1), the micro-channel SMA pipe (1) does not shrink any more.

2. The microchannel shape memory alloy tube of claim 1, wherein: when the microchannel SMA tube (1) is made of one-way memory effect shape memory alloy, the microchannel SMA tube (1) is provided with a resetting device, and the microchannel SMA tube (1) is reset through the resetting device.

3. The microchannel shape memory alloy tube of claim 1, wherein: the micro-channel SMA tube (1) has an outer diameter of 1-2mm and an inner diameter of 0.01-1 mm.

4. The microchannel shape memory alloy tube of claim 1, wherein: the shape memory alloy is one or more of nickel-titanium series, copper series and iron series memory alloy.

5. The microchannel shape memory alloy tube of claim 1, wherein: the energizing terminal (2) is connected to a power source (3).

6. The microchannel shape memory alloy tube of claim 1, wherein: a check valve is arranged between the microchannel SMA tube (1) and a cooling liquid source, and the microchannel SMA tube (1) realizes on-off control of the cooling liquid through the check valve.

7. The microchannel shape memory alloy tube of claim 1, wherein: the contraction direction of the microchannel SMA tube (1) is the axial direction.

8. A method of using the microchannel shape memory alloy tube of claim 2, comprising the steps of:

step S1, installing the microchannel SMA tube (1) into a driver and connecting a power-on terminal (2), a cooling liquid source and a resetting device;

step S2, the electrifying terminal (2) is electrified to heat the micro-channel SMA pipe (1), and the micro-channel SMA pipe (1) contracts;

step S3, the electrified terminal (2) is powered off, and the heating of the microchannel SMA pipe (1) is stopped;

step S4, enabling cooling liquid in the cooling liquid source to flow in from one end of the micro-channel SMA pipe (1) and flow out from the other end of the micro-channel SMA pipe, enabling the micro-channel SMA pipe (1) to simultaneously generate a capillary phenomenon to push the cooling liquid to flow, and enabling the micro-channel SMA pipe (1) not to shrink any more;

step S5, the microchannel SMA tube (1) is assisted to reset through a resetting device;

step S6, repeating steps S1 to S5 until the driver stops driving.

9. A driver, characterized by: the actuator uses a microchannel shape memory alloy tube as claimed in any one of claims 1 to 7.